Tuesday, March 3, 2015

Counting and Contamination Analysis in Fluid Power Systems

Counting and Contamination Analysis in Fluid Power Systems
In 1988 WearCheck introduced particle counting to its battery of tests.  
Introduction to methods of contamination analysis
Typically, most oil analysis companies have relied on spectrometric and debris analysis for the detection of wear particles and contaminants in oil lubricated components. The ICP (inductively coupled plasma) spectrometer used by WearCheck is limited to a maximum particle size of eight microns that it can detect, so other techniques must be employed to detect larger wear particles and contaminants. The ideal situation would be to filter all oil samples and examine any debris under a microscope; this is highly labour intensive in terms of sample preparation and visual analysis of the debris and only provides a qualitative description of the debris.
WearCheck uses particle quantification as a screening test to detect the presence of wear particles greater than eight microns. IN this test a bulk magnetic measurement of the oil is made and a particle quantification index is determined; depending on the level of this index and the type of component the oil has come from, a visual debris analysis will be made.
Particle quantification, however, also has its drawbacks. Because it is a magnetic measurement, it only detects the presence of ferrous particles in the oil and takes no account of other types of contaminants in the oil, eg. Coal dust, coarse dirt, fibrous material, etc. In 1988 WearCheck introduced particle counting to its battery of tests. In this test, the total number of particles, irrespective of origin, are counted in a number of sizes, ranging from 5 to 400 microns. The results are expressed as the total number of particles per ml of oil in the various specified size ranges.
A brief history of fluid power
This test is of particular importance to clean oil systems, eg, hydraulics, transmissions, turbines, compressors and other fluid power systems. It has been shown that 70-85% of hydraulic component failures are due to particulate contamination with up to 90% of these failures due to abrasive wear.
The concept of fluid power systems dates back to the times of Archimedes and the invention of the screw pump. In the 15th century, Leonardo da Vinci advanced many ideas including that of the hydraulic press. In the 16th and 17th centuries both Galileo and Pascal were involved in the development of hydraulic power theory. Many consider Pascal to be the true father of hydraulic power systems. The industrial revolution saw the development of the hydraulic press by Joseph Bramah and the use of hydraulic power was demonstrated to the Duke of York in 1813 by uprooting a tree in Hyde Park. The hydraulic power industry was finally recognized in 1925 and since that time there has been concern over contamination and cleanliness of hydraulic fluid power systems. Actual particle counting techniques were developed in the late 1950’s and early 1960’s.
WearCheck uses a Hiac/Royco model 8000A automatic particle counter.  
Particle counting techniques
In this test the oil is drawn through a membrane of known pore size and the number of particles in a variety of size ranges is counted by viewing the membrane under a microscope. Although this technique is still used today, it is tedious, time-consuming and unreproducible when compared to other techniques.
Other contaminant analysis techniques exist, such as Patch Tests, Gravimetric Analysis and determination of silting indices. All these tests, while providing total contamination levels, provide no information on the distribution of particle size.
Image analysers using video and computer systems give accurate particle count information. However, this method is time-consuming and very expenxive. In the mid 1960’s automatic liquid particle counters were developed and this is now the preferred technique for particle counting in the 1990’s as many advancements and refinements have been made with instrumentation in the last 30 years.
Automatic liquid particle counters operate on three general principles: electrical resistance, fluid flow decay and light blockage. As electrical resistance (coulter conters) devices depend on the medium under test to conduct electricity, these systems are rarely used in oil analysis. With fluid flow decay devices, such as the Diagnetics Instrument, the oil is passed through a screen of known mesh (usually ten microns) and the time taken to plug the screen is determined, the instrument then calculates the distribution in other size ranges by extrapolation. The disadvantage of using this technique is that it assumes a predetermined size distribution without actually measuring the number of particles in each size range. The most common types of automatic particle counters operate on a light blockage principle when oils are being analysed.
With this type of instrument, a known volume of oil (usually 5 ml) is injected through a very small sampling cell. On one side of the cell is a beam of laser light and on the other side, a detector. As particles pass through the cell, they block the beam of light and thus cast a shadow on the detector. The drop in light intensity received by the detector is proportional to the size of the particle blocking the light beam. In this way, both the number and size of the particles can be measured.
Particle counting by light blockage
The instrument that WearCheck uses is a Hiac/Royco model 8000A automatic particle counter and it operates on this light blockage principle.
The instrument is set up to measure particles in five different size ranges. Those size ranges, in microns, are as follows: 5-15, 15-25, 25-50 50-100 and greater than 100. The results are expressed as the total number of counts (particles) per ml of oil. With the advent of automatic particle counters it was realised that some form of categorisation of particle counts was needed in order to determine if an oil was "clean" or "dirty".
WearCheck calibrates its instrument with the ACFTD method.   During the 1960’s a number of systems for the classification of oil cleanliness was developed, among them were the SAE 749D, NAS1638 and MIL1246A.While these enjoyed some popularity in the 1960’s they were all eventually discarded, the main problem being that all these early classification systems assumed a fixed particle/size distribution.
Finally, in July 1972 a system of cleanliness classification was proposed and eventually ratified by the International Standards Organization in September 1974. The system is known as the ISO 4406 and is still in use today. This system reflects the philosophy of contamination control experts throughout the world and can be used to describe a theoretically infinite range of contamination levels in oil.
The ISO 4406 cleanliness rating is expressed as a two number code X/Y, where X represents the total number of particles per ml greater than five microns and Y represents the total number of particles per ml greater than 15 microns.
These two sizes were selected because it was felt that the smaller size would give and accurate assessment of the "silting" condition of the fluid, while the population of the particles greater than 15 microns would reflect the prevalence of "wear" catalysts.
The ISO Standard, outlined later in this article, gives an explanation of the relationship between the X/Y code and the actual number of particles per ml in the chosen size ranges.
Calibration of particle counters
For any laboratory instrument to give meaningful and accurate results it must first be calibrated against a precisely known standard. Unfortunately, there are two methods for accurately calibrating the instrument and these two methods give different results. The first method involves using a very clean oil and dispersing an accurately measured mass of mono-sized latex spheres in the oil (sometimes the spheres are made of glass).
This oil is then tested in the instrument and because the size of the particles is very accurately known, the instrument can be calibrated against known standards. This method is currently gaining a lot of popularity in western Europe and North America. The other method is to use Air Cleaner Fine Test Dust (ACFTD) dispersed in very clean oil. The ACFTD is a naturally occurring dust and the particle size distribution of the dust is known very accurately. From this size distribution an accurate calibration of the instrument can be made.
The main advantage of using ACFTD is that the particles are typical of contaminants and wear metals in hydraulic systems with regard to size and shape.
This is the only method of calibration according to the International Standards Organization (ISO 4402). The disadvantage of using this method of calibration is that the particles are not uniform (as is the case with a sphere) and the counter will measure size on the basis of the largest dimension.
Treatment in the laboratory must be standardized.   Because of the Hydroscopic nature of the test dust it is very difficult to prepare the calibrating fluid and it has a limited shelf life. Most importantly, production of ACFTD has been halted.Due to the halt in production of ACFTD it seems likely that the International Standards Organization will eventually adopt the latex sphere method for ISO 4402. It has been shown that there is a linear relationship between the two methods so that either calibration can be adopted. WearCheck is currently keeping abreast of any changes in calibration techniques for automatic particle counters.
Sampling techniques
Finally, some thought must be given to sampling techniques both in the field and in the laboratory.
Obviously the sample container must be scrupulously clean and any external contamination must be avoided, these procedures are actually laid out in the International Standards Organization method ISO 3722. Treatment in the laboratory must also be standardized and watched very carefully. For example, during transport to the laboratory, most of the contaminants will settle out so the sample must be agitated to get them evenly dispersed in the oil.
At one time it was thought that using an ultrasonic bath to agitate the sample would be an ideal method until it was discovered that the ultrasound actually breaks up some of the larger particles into smaller particles.
Although automatic particle counters are widely used and provide accurate, repeatable and reproducible results, not all oils are amenable to this test. Oils that are badly oxidized and discoloured may not transmit enough light to give a reliable result or oils that contain water give erroneously high results because the counter "see" the water droplets as particles.
Some oils actually contain wax particles suspended in them which will also provide a bad result.
What of the future?
As particle counting becomes more accepted as an analytical technique and more OEM’s and endusers become aware of the critical importance of contamination control in the hydraulic fluid power industry, the greater the emphasis will be on keeping hydraulic fluids clean.
For warranty purposes, certain manufacturers have already laid down maximum ISO 4406 ratings for the hydraulic equipment and a number of oil companies are concerned that their hydraulic fluid be as clean as is practically possible when dispatched to the customer.
In certain circumstances it has been found that some new oils do not meet the cleanliness requirements of the OEM. This does not mean the oil is no fit for use but the piece of equipment, fitted with a good filtration system, is quite capable of cleaning the oil down to very low ISO 4406 levels as the oil is continuously circulated through the filtration system.
  1. Day, M.J. Calibration of Automatic Particle Counters.
  2. Fitch, E.C.; Hong, I.T. Contamination Control in the Fluid Power Industry.
  3. Needleman, W.M. Filtration for Wear Control.
  4. ISO - 3722.
  5. ISO - 4402.
  6. ISO - 4406.

Cleanroom Tip: Controlling Relative Humidity

Failure to properly measure and control relative humidity in the cleanroom can result in lower yields, increased scrap and waste, contaminated product inadvertently reaching consumers, customer lines down, increased liabilities, and decreased revenues—among other situations best avoided. Carefully monitoring and controlling the relative humidity in a cleanroom is an absolute requirement—with no options.

Particulate count. Temperature. Airflow. Humidity. These five words are among the environmental factors that must be measured and controlled in the cleanroom environment. Sometimes the ‘stickiest’ of these is humidity. Measuring and controlling it within prescribed parameters can be a challenge. Too little or too much RH can impact much more than the personal comfort of cleanroom employees. Too little humidity can be quite electrifying—creating issues of static build-up and discharge. Too much humidity brings its own woes: encouraging the growth of bacteria and microbes, corroding sensitive metals whether in products or equipment, and manifesting itself in moisture condensation and water absorption. Then there’s photolithographic degradation. Photoresist processes are among the most sensitive to humidity, and can be among  the most costly to control for, due to their tightly required parameters. The bottom line: any of these conditions can result in cost overruns, scrapped products, and shortened equipment life. In short, the diminution of cleanroom performance, which is costly in itself.

Simply put, because humidity is relative to temperature, controlling RH within very tight tolerances or at extremely low levels can end up costing you more money in both construction and operating budgets. It’s important to understand that target humidity and temperature control decisions impact costs. A cleanroom target temperature of 65 degrees will have a lower relative humidity than a target temperature of 60 degrees. The lower your controlled temperature goes, more is required to “dry out” the air to reach a set RH level. Driving lower moisture content drives cost.

Measuring Airflow in the Cleanroom

To confirm that the system is working properly, it is necessary to check the airflow at the supply vents and also to check the distribution of airflow throughout the room. Image: Kanomax
To confirm that the system is working properly, it is necessary to check the airflow at the supply vents and also to check the distribution of airflow throughout the room. Image: Kanomax
Maintaining appropriate air velocity in the cleanroom helps ensure a clean environment; correct system performance plays an important role. To make certain the system functions as expected, periodic checks using the proper instruments are recommended to measure velocity and uniformity in the clean space.

Room performance can be affected by room size, AHU capacity, length of duct run, as well as other factors. Methods used to check airflow within a cleanroom vary depending on the ventilation set-up—the two most common being laminar flow and turbulent airflow.  

Ventilation set-up

In a laminar flow system, air flows through the cleanroom in one direction, either horizontal flow or top to bottom. Koji Miyasaka, with Kanomax, Andover, N.J., notes that, “To confirm that the system is working properly, it is necessary to check the airflow at the supply vents and also to check the distribution of airflow throughout the room. At the supply vents or fan filters the volumetric flow should be checked by using the following formula: Q = V x A. (V is the average or center air velocity and A is the area of the vent or fan filter.) To determine the total volumetric flow for the room, the procedure should be repeated at each vent or fan filter and then summed. This number should then be compared to the specifications for the cleanroom to find if it is in tolerance. Many modern anemometers come with this calculation function built in.”

In a turbulent airflow system, the room is designed to dilute and remove contaminates based on a certain number of air exchange rates per hour. To check this type of system, measure the airflow at both the supply and the returns and then calculate the number of air exchanges that occur per hour.”

Taking measure

“In unidirectional cleanrooms the airflow velocities are typically measured using either a thermal anemometer (mass flow devices) or an electronic micromanometer in conjunction with a multi-point sensor array (volumetric flow device),” says Cary Binder, ENV Services Inc., Hatfield, Pa. Binder points to guidance from IEST-RP-CC 006.3 Section 6.1.1b.1 which states, “Divide the plane into a grid of equal area. Individual areas should not exceed approximately 0.4m2 (4 ft2)” while the probe is typically placed 6-in. from the filter face or diffuser. 

Binder offers the following steps for measurement. “Calculate the effective media area of each filter and multiply the average velocity for each filter to determine the airflow volume (cfm). Add the calculated volumes for all the filters and the result is the total airflow volume for the room. Divide the total airflow volume for the room by the room volume and multiply by 60 to obtain the ACPH for the room.  When a balometer is used, simply add the measured volumes for all the filters and the result is the total airflow volume for the room.”

For more information

The contributors to this article have provided more detailed explanation and examples in articles that are hosted on the Controlled Environments website, www.cemag.us. On the site, search “air velocity” to find expanded material on the topic of airflow measurement for cleanrooms and compounding pharmacies.

Prevention Instead of Decontamination

he highest possible quality of an end product, in compliance with requirements and regulations, can be attained only if quality assurance is not merely limited to final product testing. Rather, the entire manufacturing process, besides incoming quality control of the raw materials used, needs to be continuously monitored.

In the pharmaceutical industry, risk analysis of individual manufacturing steps is performed and the results of this analysis are used to define in-process quality control tests. Such QC tests permit timely detection of inconsistencies or non-conforming items and, in particular, increases in the bioburden as they occur in manufacture so that corrective action can be promptly initiated. Even though the risk of contamination has been considerably reduced by GMP-compliant production, decontamination, and sterilization of the end products, as well as by strict hygiene standards, quality control of the final product continues to be of prime importance.

Microbial enumeration

Quantitative analysis of microorganisms involves counting the colony-forming units (CFU), hence the term “microbial enumeration.” This number can be expressed either as the total viable number of CFUs in general or of certain product-relevant species of microorganisms. This is why microbial limit tests are performed on various products from different sectors, including the pharmaceutical, beverage, and waste water industries, to ensure that defined limits are not exceeded. The accuracy and reliability of microbial limit test results are essential as they serve as the basis for the release of products, whether potable water or pharmaceuticals, and the impact of undetected pathogens can be potentially devastating on the health of consumers.

Membrane filtration

For microbial enumeration, membrane filtration continues to be the method of choice for reliable quantification of microorganisms in liquid samples. The principle of this method is based on the concentration of organisms—which are filtered out from relatively large sample volumes—on the surface of a membrane filter and their subsequent cultivation by incubating the filter with the retained microbes on a culture medium.

Unlike direct incubation of a sample, membrane filtration offers the advantage that large sample volumes can be tested without individual microorganisms going undetected. In addition, inhibitors, such as antibiotics or preservatives, can be removed by rinsing the membrane with buffer so that microbial growth is not suppressed.

Microbiological tests in the pharmaceutical industry

From a microbiological viewpoint, pharmaceuticals can be subdivided into two categories: non-sterile and sterile products. For both categories, the potential risk resulting from microorganisms and their toxins on patients’ health must be eliminated or at least mitigated. At the same time, the quality and effectiveness of such pharmaceuticals must be retained.

Products defined as sterile, such as eye drops, physiological saline, antibiotics, etc., need to be tested for sterility (USP Chapter 71 and EP, Chapter 2.6.1) in order to be verified as such. Unlike sterile products, non-sterile end products are tested for their number of viable microbes according to the microbial limit test (USP Chapter 61 and EP Chapter 2.6.12). Furthermore, in the pharmaceutical industry, in-process microbiological quality control tests are carried out on raw materials, mostly water, as well as bioburden analysis during manufacture.

Critical steps in microbial enumeration

The classic equipment setup for performing membrane filtration consists of a vacuum pump, a multi-branch vacuum manifold, membrane filters, reusable funnel-type filter holders or single-use filtration units, culture media, and tweezers.

In this method, the filter support of a reusable filter holder is sterilized by flaming, and a membrane filter is subsequently placed on this support. Then the funnel is attached to the support and a sample is poured into this funnel. Filtration begins when the tap on the vacuum source is opened. At the end of filtration, tweezers are used to remove the membrane filter and transfer it to an agar culture medium.

The culture medium is incubated for a defined time at a predetermined temperature inside an incubator. At the end of incubation, evaluation is done by enumerating the individual CFUs and comparing their count with the permissible microbial limits for each particular sample.

Flaming or disinfecting the filter support poses an added risk of contamination due to the inherent inaccuracy in performing these sterilization procedures. In particular, maintaining the required time of contact with the flame or disinfectant, the choice of disinfectant (not just a bactericide, but a sporicide) and regular changing of the disinfectant are all critical factors in determining whether sterilization is 100% effective. Besides representing a health hazard for lab personnel, flaming also poses the risk that not all areas contaminated by microbes are exposed to the hottest point of the flame long enough in order to kill off these organisms.

Minimization of secondary contamination

A single-use filter unit does not require any decontamination, provided that a single-use filter base is used. As a result, the only especially critical step that remains is transferring the membrane filter to an agar medium, which increases the risk of secondary contamination and can lead to false-positive results. The reason lies in the use of tweezers to transfer the membrane. Although these tweezers are also flamed, i.e., sterilized, they can potentially carry over exogenous microbes when used to grasp the membrane.

Single-use filter units increase the safety and efficiency of microbiological quality control by eliminating the need for disinfection or flaming of the filter support, as well as for using tweezers to transfer a membrane to a culture medium. A system comprised of single-use filter units and agar media dishes can increase efficiency and reliable results.  

The filter unit in this type of system is a sterile, ready-to-use combination of a funnel, a filter base, and a gridded membrane filter. This filter unit is connected to a stainless steel multi-branch manifold in order to directly filter a sample. Afterwards, the filter unit is easy to remove from the manifold and eliminates the critical step of decontaminating the stainless steel base of a reusable filter holder.

Agar media dishes are used for microbial limit testing. They are pre-filled with different types of agar medium, sterile-packaged and, when together with a single-use filter, are ready to use immediately. In combination with a single-use filter unit, these media dishes feature an active lid that permits touch-free transfer of a membrane onto agar, without using any tweezers. This active lid lifts the membrane filter from the base of the filter unit so the filter can be safely transferred onto the pre-filled agar dish. Once the medium dish is closed, the membrane is ready to incubate.

Solution for safe membrane transfer

The combination of agar media dishes and filter units represents a new membrane transfer and agar concept. As just a few steps are all it takes to proceed from sampling to incubation, a single-use system of agar media dishes and filter units accelerates workflows, making them cost-efficient. At the same time, touch-free membrane transfer enables even more reliable results to be obtained in analysis, while reducing secondary contamination to an absolute minimum.

Immediate Benefits of Real-Time Microbial Monitoring

Companies producing medicines and biotech products are concerned with airborne microbial contamination. They need to ensure that products and people are kept safe. The traditional, accepted method to test for microorganisms at critical locations in a process is the use of active air samplers or settling plates. Typically, 1-meter-cubed samples are taken onto agar plates and sent to a lab for culturing. The colony forming units (CFUs) results come back from the lab after four to ten days. Only after this waiting period will end users know whether the manufacturing environment was in control. Recently, the commercialization of a technology based on laser induced fluorescence (LIF) has made it possible to look at airborne viable microbial counts in real time. The potential to instantly respond to an airborne microbiological event when it happens is exciting—and beneficial.

Root cause analysis

Results from active air samplers are important—they can inform us that there has been a problem, possibly an excursion of some kind, and also enable identification of the microorganism to support a root cause investigation. However, they do not tell us when the contamination happened, or the source of the contamination. New LIF-based bio-detection products can provide better insight into these unknowns by measuring airborne viable particle counts and displaying this data in real-time. The data can be viewed via a local display or integrated directly into a facility monitoring system (FMS).

One quality assurance professional recently stated that their company spends thousands of dollars each year looking for root cause of microbial contaminations, with limited success. Positioning air samplers or settle plates to narrow down the source of airborne microbiological contamination is difficult and time consuming. Even when using good scientific and risk-based approaches, there is at least a four-day wait to know the result. And, taking periodic samples simply does not provide enough information to find root cause. But, with real-time viable particle counters, time-resolved data can provide valuable insights into root cause. An immediate notification to presence of airborne viable particles means finding the source could potentially take minutes instead of days or weeks. Furthermore, the instrument sample probe can be attached to sample tubing and is identical to ones used by standard optical particle counters. The probe can be configured to beep every time an airborne viable particle is detected, just like a Geiger counter, enabling end users to sniff out the exact location of the contamination source.

Another example is contamination that comes from workers, particularly when they start a shift in a cleanroom. By having data to support the impact of gowning practices on cleanliness, companies can provide enhanced training programs. Once root causes are identified, actions can be taken to rectify the issue, be it training, ventilation, filtration, machine maintenance, or facility adjustments.

Process improvement

Regulatory authorities are very interested in root cause investigations, and what preventative and corrective actions were taken to ensure the problem will not occur again. When real-time viable particle counters are integrated into a FMS software package, the data can become the basis of informational reports that offer insight into processes, providing alarms, warnings, and trending. Quality control is typically concerned with product, alarms, excursions, and corrective actions. Quality assurance is more concerned with process, trending, and preventative actions. With real-time airborne microbial data, reports can be viewed with an eye toward preventative maintenance and identifying adverse trends before a microbial excursion occurs. (Figure 1)

Figure 1: Quality control utilizes alert and action limits for reactive and corrective activities. In Quality assurance, attention is placed on trending data, process improvement, and preventative actions.
Figure 1: Quality control utilizes alert and action limits for reactive and corrective activities. In Quality assurance, attention is placed on trending data, process improvement, and preventative actions.
One challenge in critical ISO 5 or Grade A pharmaceutical processing environments is that they are very clean. Much cleaner than when the cleanliness limits detailed in the cGMP Aseptic Processing guidance was conceived. Today, Grade A isolators are continuously monitored for airborne contamination using active air samplers, settle plates, and traditional optical particle counting technology. When correctly designed, these environments easily meet and exceed the airborne cleanliness requirements as defined in the GMPs. In some cases, many weeks, months, and even years will pass without any airborne microbial contamination being detected using current methods. Similarly, low numbers are seen in surrounding Grade B environments.

It is surprising, then, that these very clean critical processes have to be interrupted, growth media introduced or manipulated, in order to meet the regulatory requirement for AAS environmental monitoring. The good news is these potentially hazardous and disruptive process steps are unnecessary with real-time airborne viable particle counting technology. Real-time viable particle counters not only offer the potential to monitor these very clean and well-controlled environments, but can also provide continuous data when integrated into an FMS system.

Saving time and money

In today’s competitive environments, facilities are always looking for ways to save time and money. Real-time viable particle counters provide opportunities for real savings. Similar to the example above, let’s look at an isolator. One pharmaceutical company has calculated that they could increase line capacity of an isolator by over 20% by reducing the downtime required to change agar plates with active air samplers. Agar plates have to be changed every three to four hours as they will dry out and not support growth. By using a real-time viable particle counter, the need for changing agar plates could potentially be eliminated, or at least minimized, saving valuable equipment downtime and optimizing labor. This also saves on the production time required to re-establish a clean environment in the isolator before production can begin again. This approach could potentially save thousands of dollars per year for each isolator.

Room certification after construction, renovation, and room changeover can be a lengthy and expensive process for facilities, taking upwards of three to seven days while waiting for incubation results to release a zone. However, with real-time viable data in an FMS system, rooms could be released in an hour or less, providing facilities with the opportunity to increase utilization rates of expensive rooms and equipment.

Another operational concern is energy. Energy is expensive. And cleanrooms, with a high number of air changes and HEPA filtration, generally use a lot of energy. If the air change rate could be reduced, while maintaining cleanliness levels, facilities could potentially see significant savings. Cleanroom studies can be performed with a real-time viable particle counter to see if air change rates can be reduced. Of course, at no time should any energy-saving measures take precedence over product safety.


Modern technology continues to move forward, providing better measurements and data. In the case of microbial detection, new LIF-based products provide real-time viable particle counts. This data, when integrated into a facility monitoring system, allows users to see information in the form of reports and test results. Then, the information can be used to develop knowledge of facilities and systems. Knowledge is a powerful tool when looking for root causes of excursions, for process improvements, and for opportunities to save time and money.

But do regulators embrace this new technology and information? The answer appears to be yes. Regulatory bodies certainly want to ensure that medicines and biotech products are safe for consumers. To that end, they want to be sure that root causes are identified, with corrective and preventative actions put in place. And they want process improvements to provide an even higher level of safety in the future. Vendors of real-time viable particle counters have submitted a Type V Drug Master File (DMF) with the U.S. FDA. This provides the FDA and customers with a file that demonstrates the science behind the technology, as well as the test results to support the measurements.  
Troy Tillman is a Senior Global Marketing Manager for Contamination Control at TSI Inc. He has spent over 20 years defining and developing products for markets such as pharmaceutical cleanrooms, laboratories, hospitals, and vivariums. He has been an active member in IEST, ASHRAE, and CETA, speaking at numerous conferences. www.tsi.com; pr@tsi.com.

This article appeared in the September 2014 issue of Controlled Environments.

Liquid Particle Counting Applications in Pharmaceutical Manufacturing

With water contributing the largest component of pharmaceutical products, especially injected products, control of the quality of water in both systems and finished product is paramount. The particulate burden of finished product is a Pharmacopoeia regulation in the major standards documents, USP<788>1 and USP<789>2, EP<2 .9.19="">3, and JP<6 .07="">4.

Figure 1. Light obscuration particle counter schematic.
Figure 1. Light obscuration particle counter schematic.
Figure 2. Light scattering particle counter schematic.
Figure 2. Light scattering particle counter schematic.
It should be noted that particle counting is not a method for determining the distribution of particles in a suspension, as here the particle burden would saturate the optics of most commonly used particle counters employed in contamination controls; there is an expectation that the liquids being tested are “essentially free” from contamination and the particle counter is looking for particles possibly caused by events in the handling and management of the water supply that has caused an out of control condition.


There are two primary methods for measuring the particle contamination of liquids: light obscuration and light scattering.

Light obscuration particle counting is where a beam of light (laser) is directed through a narrow capillary tube with a flowing stream of liquid; any particle passing through the laser beam blocks a certain amount of light and casts a shadow across the photo-detector. The amount of light blocked is equivalent to the size of the particle in the liquid; accurate sizing of the detected particles can be determined by calibrating the particle counter with particles of known sizes suspended in clean water.

This method of light obscuration is ideal for measuring particles that are relatively large, 1.5 microns (1.5 µm) up to over 150 microns (150 µm); particles greater than 150 µm are typically within the range of those particles that are potentially visible.

For smaller particles than the 1.5 µm lower limits of light obscuration, light scattering is used.

Light scattering is where the laser beam is directed through a narrow capillary tube with a flowing stream of liquid. When a particle within that stream passes through the laser beam light is scattered off the particle by several different interactions with the particle’s surface (reflection, diffraction, and refraction), this scattered light is then collected using a series of mirrors and focused onto a photodetector for analysis. The amount of light scattered off a particle is equivalent to its size; i.e. the bigger the particle the more light is scattered, and accurate sizing of particles within a liquid can be determined by the calibration of a particle counter against known size standards.

This method of particle counting using scattering is used for volumetric instruments down to 0.2 µm and is effective up to above 20 µm. Below the 0.2 µm threshold volumetric sensors tend to give way to non-volumetric instruments where only a small fraction of the total liquid flow is monitored.


There are two primary applications for particle counters in production environments: the primary one being the testing of finished products to those standards identified above and a second one of monitoring the quality of the water for injection (WFI).

Testing of finished products to the Pharmacopoeia standards is performed against a strict test requirement. Test samples comprise of either a pooled sample of small injectable products, sufficient to perform testing. A minimum of 10 pooled containers should be used, or where large production volumes are manufactured a portion of several individual containers can be used. These differences are based upon the finished products’ normal supplied volume being less than or greater than 100ml. The sample is drawn using a syringe sampler through a light obscuration particle counter and the number of particles measured are reported as either particles per container volume, or particles per ml. The current limits for maximum allowable concentrations are given in the table below.

Instruments used for performing these tests must be validated to meet the requirements of “suitably calibrated” and the regional requirements for count standard accuracy.

The second application for particle counters is for demonstrating control over the particle burden of the WFI system. There are no current regulations that require monitoring be performed; however, several facilities that have employed particle counters on the WFI loop have been able to notice when filters are beginning to degrade as there is a shift in the distribution of particles remaining in the water. When filters begin to blind and the smaller pores block, two thing occur: a rise on pressure across the filter, and a shift in the distribution of particles where the smaller sized particles increase relative to the overall population. It is common to change filters based upon either a maintenance schedule of time, or an increase in the pressure drop across the filter, where particle counters have been employed; however, filter life can be extended as the distribution shift is monitoring, or shortened as increases in overall levels of particles is witnessed in the clean supply.

Table 1. Current Pharmacopoeia Limits for Finished Product.
Table 1. Current Pharmacopoeia Limits for Finished Product.
It also allows for the identification of when a recirculation problem may exist within a filling tank; if the recirculation pumps on the system begin to fade, the filters become less efficient (overall volume filtered) and so a recovery of the system can be identified.


1. USP <788>. Particulate Matter in Injections, United States Pharmacopoeia 37-NF 32, May 1, 2014
2. USP <789>. Particulate Matter in Ophthalmic Solutions, United States Pharmacopoeia 37-NF 32, May 1, 2014
3. EP <2 .9.19="">. Particulate Contamination: Sub-Visible Particles, European Pharmacopoeia 5.0, January 2005.
4. JP <6 .07="">.  Insoluble Particulate Matter Test for Injections, The Japanese Pharmacopoeia 16, March 2011
Mark Hallworth, Market Manager for the Life Sciences Division of Particle Measuring Systems in Boulder, Colo., has spent over 17 years with the company. He has over 25 years’ experience in particles, including their transportation and measurement in many industrial and scientific applications. He has designed several instruments for the measurement of particles, including extreme environmental conditions and fully integrated controls systems, which has led to software products that meet the demands of a regulated industry. mhallworth@pmeasuring.com; www.pmeasuring.com 

This article appeared in the October 2014 issue of Controlled Environments.


Instantaneous Microbial Detection for Water

Water is utilized abundantly to process, formulate, and manufacture pharmaceutical products. Traditional culture-based methods used to ensure water quality, however, are ill-suited in providing a robust assessment of risk and control. These methods are plagued by limitations in sensitivity, episodic sampling, and retrospective results. New technologies based on laser-induced fluorescence (LIF) detect intrinsic fluorescence instead of growth, can operate continuously, and deliver real-time results. As applied to pharmaceutical water quality, LIF-based, instantaneous microbial detection technologies enable real-time bioburden monitoring, risk reduction, and process control.

Figure 1: Emission spectra of two microorganisms and eight materials with 405nm excitation. An approximate Raman band for water and two example detection ranges for an instantaneous microbial detection system with two PMTs are labeled.
Figure 1: Emission spectra of two microorganisms and eight materials with 405nm excitation. An approximate Raman band for water and two example detection ranges for an instantaneous microbial detection system with two PMTs are labeled.
The pharmaceutical industry continues to recognize a need to leverage modern technologies to advance the course of risk reduction and process control. This forward thinking has been captured in industry relevant guidance such as the FDA’s 2004 “Guidance for Industry” document on Process Analytical Technology (PAT), ICH Guidelines Q8, Q9, and Q10, and the FDA’s “Pharmaceutical cGMPs for the 21st Century,” which encourage the adoption of quality by design (QbD) principles and new technologies. More recently, working groups composed of representatives from key pharmaceutical companies have also joined forces to help articulate their needs in water quality assessment and encourage the development and use of new technologies best suited to today’s tasks.

Need for an online pharmaceutical water assessment tool

The currently accepted and primarily practiced method for assessing water quality throughout a pharmaceutical water loop is through samples obtained at points-of-use (POU), utilizing traditional culture-based methods. The goal of such testing is to ensure the quality of an entire water system; however, POU testing can occur as infrequently as once every two weeks at each sample point. This limited sampling frequency, combined with the retrospective nature of culture-based methods, make a robust and timely assessment of risk and control difficult. Furthermore, there is the potential for sample contamination during collection (a false positive), and for a false-negative result due to limitations in sensitivity of culture-based methods. While growth-based methods offer the opportunity for identification, a number of organisms go undetected, such as viable but non-culturable organisms, due to the chosen medium and incubation parameters. A complementary technology capable of real-time and continuous monitoring of water system bioburden, based on a different method of detection, could alleviate such limitations and aid in risk reduction and process control.

Table 1: Business benefits summarized in the OWBA Business Benefit Estimates document.
Table 1: Business benefits summarized in the OWBA Business Benefit Estimates document.
Online pharmaceutical water bioburden analyzer

With an aim to improve the tools being applied to pharmaceutical waters, an Online Water Bioburden Analyzer (OWBA) Workgroup recently outlined user requirements, a testing protocol, and business benefits to guide the development of an OWBA system.1,2,3,4  This workgroup, composed of representatives from seven major pharmaceutical companies, has a mission to aid instrumentation vendors in the creation of an online water bioburden analyzer that satisfies both industry and regulators. They believe, “an online water bioburden analyzer has the potential to eliminate sampling and testing errors via reduced manipulations while providing increased product safety and process control through the availability of statistically significant data.”3 According to the group, such an OWBA system is not primarily designed to eliminate compendial water testing, but should be used as a risk reduction tool. Potential business benefits are shown in Table 1 and include energy savings, labor reduction (resource allocations), and increased product quality and process understanding.2

Figure 2: With a scatter detector and two fluorescence detectors (PMTs), an instantaneous microbial detection system for water can create a three-dimensional plot of biologic and interferent particles. Through assessment of the three different signals and an advanced processing algorithm, such a system offers enhanced interferent discrimination capabilities.
Figure 2: With a scatter detector and two fluorescence detectors (PMTs), an instantaneous microbial detection system for water can create a three-dimensional plot of biologic and interferent particles. Through assessment of the three different signals and an advanced processing algorithm, such a system offers enhanced interferent discrimination capabilities.
Technical system requirements are provided, which include specifications for bioburden sensitivity, calibration, chemical compatibility, operating parameters, and needed consumables.3 Also included is a requirement for a limit of detection (LOD) equivalent to that set forth for culture-based methods (10 CFU/100mL) and analysis modes that include continuous sampling, time-based sampling, and daily operation at designated times. Overall, the system should be capable of continuous and periodic monitoring of critical control points (CCP) and POU, with sufficient sensitivity to detect microorganisms in water and limited susceptibility to potential interferents such as rouge, residual sanitizer, and gasket materials.

Laser-induced fluorescence

One technique capable of satisfying the OWBA requirements is laser, or light, induced fluorescence (LIF). LIF is a spectroscopic technique capable of high sensitivity in the detection of compounds that fluoresce. Fluorescence is the luminescence that occurs with the absorption of radiation at one wavelength followed by the emission of radiation at a different wavelength. Substances that typically fluoresce may be referred to as fluorophores. Quinine is a familiar fluorophore due to its presence in tonic water.

The application of LIF to detect microorganisms has been leveraged in flow cytometry, capillary electrophoresis, solid-phase cytometry, adenosine triphosphate bioluminescence, and growth-based auto fluorescence. In a number of these techniques, microorganisms are dyed to increase the measurable fluorescence. Measuring the intrinsic fluorescence of a microorganism removes the requirement for dyes and sample preparation, but requires an instrument with significant sensitivity. As lasers of additional wavelengths at higher power levels have become commercially available, LIF has become very relevant in applications requiring detection of low levels of microbial intrinsic fluorescence.

A light source such as a laser is the excitation source in LIF. A laser of appropriate wavelength and intensity is capable of inducing intrinsic fluorescence emission from microbes due to constituent fluorophores such as tryptophan, nicotinamide adenine dinucleotides (NADH), and flavins that are present in microorganisms.7 The target excitation wavelength is based on the excitation spectra of target fluorophores such that sufficient fluorescence intensity is induced for measurement and a greater number of non-biologic materials may be excluded. Yet, non-biologic materials such as plastics, rubbers, and paper can also fluoresce pointing to the importance of software discrimination algorithms.

OWBA: Instantaneous microbial detection technology for water

An OWBA system based on LIF enables the instantaneous detection of microbes in water, without the need for consumables and the limitations presented by traditional testing methods. Commercially available systems for water employ a 405nm laser to simultaneously induce Mie scatter and intrinsic fluorescence, on a particle-by-particle basis, as a sample travels along a flow path and traverses this excitation source. Detection and correlation of the Mie Scatter and fluorescence signals provide real-time information on the presence and biologic status of particles. Detection based on the intrinsic fluorescence of microorganisms removes requirements for sample preparation. Furthermore, this fundamental method of detection is inherently different from traditional growth-based methods, and is not susceptible to the growth-based limitations resulting from improper media selection and incubation.

Figure 3: Representative data from the IMD-W system showing IMD-W biologic counts as compared to colony forming unit culture results obtained using the traditional method with TSA plates.
Figure 3: Representative data from the IMD-W system showing IMD-W biologic counts as compared to colony forming unit culture results obtained using the traditional method with TSA plates.
In LIF-based systems, intrinsic fluorescence is captured on a photomultiplier tube (PMT), a detector highly sensitive to light. Both one-PMT and two-PMT designs are available. In water, two-PMT designs provide better discrimination of non-biologic fluorescing materials such as rouge, as requested in the OWBA requirements.3 Each material and microorganism has a different excitation and emission spectrum. Once an excitation wavelength has been chosen, some materials show a broad fluorescence emission and others a narrow emission spectrum. Similarities in the emission spectra of biologic versus non-biologic materials can be used advantageously. Figure 1 contains the emission spectra of certain biologic and non-biologic materials with 405nm excitation. Two notional PMT detection regions have been highlighted on either side of a Raman band in this figure. The Raman band represents fluorescence produced from the interaction of the laser light with water. Therefore, in order to detect particulate within the interrogated water stream, this band must be avoided in the detection regions utilized by the system. With 405nm excitation, the Raman band for water has a maximum at approximately 469nm8

With two PMT detection regions, the differences in non-biologic versus biologic emission spectra can be utilized to aid in the classification of non-biologic materials as inert. As shown in Figure 2, a particle’s scatter and fluorescence signals can be combined to create a three-dimensional map of interferent and biologic particles. Advanced algorithms can then be utilized to aid in the discrimination of biologic and interferent materials.

Real-time bioburden monitoring, risk reduction, and process control

The use of an instantaneous microbial detection system for pharmaceutical water provides the ability to monitor bioburden continuously and in real time, resulting in an increased potential for risk reduction and process control. Figure 3 shows representative data from the IMD-W™, a system designed with the OWBA requirements in mind, comparing IMD-W biologic counts to culture plate results for three OWBA suggested organisms. This data covers a wide dynamic range and speaks to the potential sensitivity and ability of such systems to monitor bioburden.

The continuous data offered by these systems creates a robust historical dataset that is ideally suited for trending, particularly when compared to episodic sampling with traditional methods. Sampling considerations set forth in “USP<1231> Water for Pharmaceutical Purposes” recommends monitoring pharmaceutical water systems at a frequency “sufficient to ensure that the system is in control and continues to produce water of acceptable quality.”5 The general information chapter states it is best to operate monitoring instrumentation in a continuous mode such that a large volume of in-process data can be generated, and suggests the use of trend analysis as an alert mechanism for loop maintenance.5  A combination of historical trending data and real-time results enable users to identify an out-of-specification event or deterioration in microbiological control significantly earlier than with traditional sampling methods. By continuously monitoring the state of control, timely loop maintenance can be performed if bioburden data trends upward, permitting further risk reduction and an increased level of loop control. A real-time and historical knowledge of control can also be important during a POU testing deviation.2 If POU testing is positive for microbial contamination, knowledge and data to support a state of control may narrow the root-cause investigation to the POU as opposed to contamination in the entire loop.


Regulatory guidance and calls from industry work groups support the need for better tools for pharmaceutical water monitoring. New instantaneous microbial detection systems based on LIF enable real-time bioburden monitoring, increased risk reduction, and process control for pharmaceutical waters. Through continuous monitoring, these systems provide significant historical data for robust trending and assessment of water loop bioburden levels, providing the means to monitor the level of control and react to out-of-specification events in a much more timely manner than with traditional methods alone. Users stand to benefit through increased product quality and process understanding, energy savings, and risk reduction.

1. Cundell, A., Luebke, M., Gordon, O., Mateffy, J., Haycocks, N., Weber, J. W., et al. (2013, May 16). On-Line Water Bioburden Analyzer Business Benefits Estimation. Retrieved August 8, 2014, from http://www.miclev.se/fileadmin/user_upload/jennie/Online_Water_BioBurden_Analyzer_Business_Benefits.pdf .
2. Cundell, A., Gordon, O., Haycocks, N., Johnston, J., Luebke, M., Lewis, N., et al. (2013, May/June). Novel Concept for Online Water Bioburden Analysis: Key Considerations, Applications, and Business Benefits for Microbiological Risk Reduction. American Pharmaceutical Review, 26-31.
3. Cundell, A., Luebke, M., Gordon, O., Mateffy, J., Haycocks, N., Weber, J. W., et al. (2013, March 18). On-Line Water Bioburden Analyzer User Requirement Specifications (URS). Document ID OWBA-DURS-2013-v1.3.
4. Cundell, A., Luebke, M., Gordon, O., Mateffy, J., Haycocks, N., Weber, J. W., et al. (2013, April 24). On-Line Water Bioburden Analyzer Testing Protocol. Document ID OWBA-TP-2013-v1.5.
5. USP<1231> Water for Pharmaceutical Purposes. Pharmacopeial forum, Vol. 32; United States Pharmacopeial Convention, Inc.: Rockville, MD, 2008.
6. Lakowicz, J. R. (2006). Principles of Fluorescence Spectroscopy (3rd ed.). New York: Springer Science & Business Media.
7. Ammor, M. S. (2007). Recent Advances in the Use of Intrinsic Fluorescence for Bacterial Identification and Characterization. Journal of Fluorescence, 17:455-459.
8. Rouessac, F., & Rouessac, A. (2013). Chemical Analysis: Modern Instrumentation Methods and Techniques (2nd ed.). West Sussex: John Wiley & Sons.

Some Thoughts on Healthcare Facilities

Q: Could you touch on some basics regarding controlling the environments in hospital and healthcare settings?

A: “The [Five Second Rule] has many variations, including The Three Second Rule, The Seven Second Rule, and the extremely handy and versatile The However Long It Takes Me to Pick Up This Food Rule.” ~Neil Pasricha,The Book of Awesome
The five second rule on avoiding germs and infections is the subject of much light hearted banter, but the implications of healthcare associated infections (HAIs) are not. Healthcare facilities are fraught with bacteria, germs, infections, contaminated biological waste, bugs, superbugs, viruses, and any number of options to threaten our health. Hospitals, in their frontline role fighting disease, couldn’t have it any other way. 

The results of this simple fact are daunting. The below chart, from the Centers for Disease Control and Infection, outlines the occurrence of HAIs based on a CDC survey of large acute care hospitals. Further, the CDC states that HAIs infect about 1 in 25 hospital patients every day, sometimes with more than one healthcare-associated infection. Estimates vary, but HAIs claim the lives of about 75,000 hospital patients during their hospitalizations, and more than 100,000 overall – exceeding that of fire, drowning, and accidents. More than 50 percent of all HAIs were picked up in areas other than the intensive care unit.

Estimates of Healthcare-Associated Infections Occurring in Acute Care Hospitals in the United States, 20111
Major Site of Infection Estimated No.
Pneumonia 157,500
Gastrointestinal illness 123,100
Urinary tract infections 93,300
Primary bloodstream infections 71,900
Surgical site infections from any inpatient surgery 157,500
Other types of infections 118,500
Estimated total number of infections in hospitals 721,800

The new healthcare regulatory environment has focused on readmissions, many caused by infections, and putting some bite into the government’s bark by reducing reimbursements to healthcare organizations reporting high levels of readmission. HAIs, by the way, account for almost one-third of hospital readmissions, not to mention racking up a healthcare cost of more than $47 billion.

While the vast majority of HAIs are attributed to the lack or inadequacy of simple hand washing - prompting many architects to strategically locate wash stations where healthcare providers need to almost trip over them – other points of control (or contamination) abound. Air circulation systems, surgical suites, isolation units and rooms, procedure areas, even the magazines in waiting areas can be rife with potential infection. What’s a hospital or healthcare facility to do? What role does the facilities engineer play in this challenge of epidemic proportions?

Following are some key areas every healthcare facilities professional should consider in their war on germs:

1. Housekeeping: Any analysis should start with the low hanging fruit offering great potential payback. Housekeeping is one of those areas. A colleague who spent some time with a relative on the organ transplant unit at Massachusetts General Hospital (MGH) related how impressed she was that the housekeeping staff was considered an integral part of the patient care team.  MGH (affectionately nicknamed “Man’s Greatest Hospital” by staff and patients) undertakes some of the most complicated and ground breaking transplants in the world. But all that cutting edge medical knowledge will fail if patients with impacted immune systems are lost due to sloppy housekeeping.

St. Mary’s Regional Medical Center. In hospital ORs, the selection of all room finishes should focus on durability and cleanability to reduce the risk of healthcare associated infections (HAIs). Credit: Sandy Agrafiotis, Photographer; SMRT Architects and Engineers.
St. Mary’s Regional Medical Center. In hospital ORs, the selection of all room finishes should focus on durability and cleanability to reduce the risk of healthcare associated infections (HAIs). Credit: Sandy Agrafiotis, Photographer; SMRT Architects and Engineers.
Bacteria and germs can hide in surprising places: one national study found that soap dispensers – more specifically, the nozzle users press to obtain soap – harbored more bacteria and germs than toilet seats.

Bottom line: stay in tune with your housekeeping staff, and develop an ongoing training and monitoring system. Housekeeping plays an important role in patient health, while impacting readmission statistics and reimbursements.

2. Plant maintenance: In times of tight budgets, it’s tempting to defer maintenance. Don’t.

In 2001 the largest historic outbreak of Legionnaire’s disease is estimated to have sickened more than 800 in Murcia, Spain. Subsequent investigation linked the outbreak to a hospital cooling tower.2 And in 2006, the borough council of Barrow-in-Furness in the U.K. and the architect of the community’s Forum 28 Arts center were fined after a trial concluded the 2002 Legionnaire’s outbreak in that community was attributable to their cooling tower. While they were likely relieved to be cleared of more serious corporate manslaughter charges, the cost was much higher on many fronts than careful design and maintenance would have been.

It’s important that healthcare facilities design to both required maintenance and the capabilities of the institution’s maintenance staff. Your systems (including piping, ductwork, and exhaust of air handling, water supply systems, decorative elements such as fountains, and your mechanical areas) should be easy to access, inspect, and maintain. 

It’s important that healthcare facilities develop and execute a comprehensive maintenance staff training program, and it’s important to identify all facility components capable of transmitting or contributing to HAIs, then develop a corresponding maintenance program.

3. Codes or a higher standard of care?: In designing new or renovated healthcare spaces, serious consideration should be given to the level of desired design, based upon the function of the space, its clinical program, and the risk of HAIs. Design identified as “best practice” earned that label through study and clinical results. Sometimes designing to code is adequate; sometimes it’s nothing more than meeting the minimum requirements.

4. Humidity control: Humidity levels play a major role in maintaining health and avoiding impacts from bacteria, viruses, fungi, mites, molds, and chemical interactions. While optimal humidity levels vary both between types of healthcare facilities and within specialized areas of healthcare facilities, many advocate for a relative humidity level between 40% and 60%, with operating rooms around 50%, ICUs around 40%, and patient rooms around 45%.

MaineGeneral Alfond Center for Health. Laminar flow diffusers and a perimeter air curtain maintain a sterile field over the patient in this surgical suite. Credit: © Anton Grassl/Esto; SMRT Architects and Engineers.
MaineGeneral Alfond Center for Health. Laminar flow diffusers and a perimeter air curtain maintain a sterile field over the patient in this surgical suite. Credit: © Anton Grassl/Esto; SMRT Architects and Engineers.
In critical care and procedure rooms, special attention should be paid to the locations of humidistats. There can be a large difference in the humidity levels of a patient occupied area such as in a surgical suite, and a humidistat is located on a far wall. While a generally accepted best practice is to locate humidistats in the return air duct as close to expected patient locations as practical, it’s important to remember to provide access for cleaning, servicing, calibrating, and replacement.

Tying your humidistats, as well as other building conditions monitoring tools, into a Building Management System (BMS) will allow continuous monitoring of critical conditions, provide real time alerts when systems fall out of calibration, and reduce the risk of human oversight.

5. It’s in the air we breathe: Books can (and have been) written on this subject, far outstripping the editorial space for this column. Suffice it to say, the pinnacle of superior air quality depends upon the volume of new air circulating in a space, dilution, carefully calibrated filtration and, where appropriate, either positive or negative pressurization. Each of these factors will require varying parameters, depending upon the location and use of the area. Lobby or surgical suite? NICU or cafeteria? The end use will prescribe the air handling specifications.

While the facilities engineer is always balancing cost, efficacy, maintenance requirements, and a myriad of other factors in determining appropriate systems, the brave new worlds of reimbursement formulas and liability have added additional considerations.

6. Future thinking: The futurists of the world are enamored with healthcare. New materials and processes are constantly being introduced, the healthcare R&D world is buzzing. Expect continuing developments in HVAC systems and controls, materials including the accepted UVGI systems, copper and silver infused products, non-toxic and anti-fungal bio-based textiles, and a host of other new technologies and modifications to known options. While some of these materials and systems carry a high price tag, continuing R&D efforts are expected to bring down costs.

7. In closing: Every healthcare facilities professional, architect, and engineer should have a copy of Guidelines for Design and Construction of Hospitals and Outpatient Facilities, 2014 edition, published by The Facilities Guidelines Institute. This handy reference, all 400+ pages, includes the ANSI/ASHRAE/ASHE Standard 170-2013: Ventilation of Healthcare Facilities. You can order a copy through www.fgiguidelines.org or by calling 1-800-242-2626.

This handy tome will provide much more information, and might possibly be the antidote you need on those sleepless nights when your mind is pondering the challenge of keeping your facilities healthy for the sake of your patients, staff, and the public. But remember, it starts and ends with the patients.


1. Magill SS, Edwards JR, Bamberg W, et al. Multistate Point-Prevalence Survey of Health Care–Associated Infections. N Engl J Med 2014;370:1198-208.
2. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3020623/

The Evolution of Cleanroom Design

Cleanrooms certainly have come a long way since their formal introduction in 1962. Imagine what it was like prior to this time when a cleanroom consisted of a "sealed-off area" that was vacuumed, and vacuumed often. It's a far cry from the high standards of contamination control we've become accustomed to today. The antiquated and questionable success of vacuuming a sealed off area all changed when, in 1959, physicist Willis Whitfield had the idea to "sweep" a dedicated area with highly filtered air. The results were dramatic and after some fine tuning, the marketplace was formally introduced to cleanrooms in 1962 … and thus, an industry was born.

Fast-forward 52 years, and cleanrooms have enabled the electronics, computers, and information technology industries to reach the level of sophistication with their products that we have come to expect. Further breakthroughs in biotechnology, nanotechnology, health sciences, and healthcare are also directly attributed to the sophisticated capabilities of cleanrooms as we know them today. To reflect upon the big picture, these advancements have dramatically impacted and benefited society.

As filtration technology has evolved over the years, so have cleanroom designs. Most common are the hard and soft walled options. Both are extremely effective designs when dealing with expansive or small requirements. However, these designs aren't the ideal solution for everyone. Somewhere in between the hard walled and soft walled users you'll find a group who require a more flexible, tailor made solution. Leading the charge in finding this solution are those customers who are focused on not being impeded by conventional limitations. What this forward thinking group is quickly discovering is that retractable cleanrooms are the ideal solution in addressing a whole host of challenging requirements. When you add in the fact that they also affect the bottom line, they are a very attractive solution.

30'H x 40'W x 25'L Retractable Cleanroom, Class 10,000.  Courtesy of Duroair Technologies.
30'H x 40'W x 25'L Retractable Cleanroom, Class 10,000. Courtesy of Duroair Technologies.
Who are these customers somewhere in the "middle" that are choosing retractable cleanrooms? Some of them are just ready to rethink the way they have always done things in the past, and are eager to modernize their processes. For others, they may only require a cleanroom environment a handful of times a year. When evaluating the cost of traditional options, the financial investment doesn't make sense. Or perhaps they are dealing with oversized components, and find that a traditional design presents too many restrictions in terms of their material handling. Much like putting a round peg into a square hole, traditional options are an ill fit. Or maybe they have limited floor space and dedicating it to a fixed structure is not an option yet they cannot do without cleanroom capabilities. These are just a few of the challenges that are being successfully resolved with retractable cleanrooms.   ENTRIES OPEN:
Establish your company as a technology leader. For 50 years, the R&D 100 Awards, widely recognized as the “Oscars of Invention,” have showcased products of technological significance.

Capable of addressing very specific requirements and offering additional value, retractable cleanroom environments are becoming an increasingly popular choice for many applications, especially within industries such as aerospace, defense, and many types of manufacturing. With the combination of custom sizing and mobility, prospective customers quickly recognize the value proposition this option offers.

In terms of meeting ISO standards set out for cleanrooms, the retractable design (and, more importantly, the filtration options to partner with them) are achievable. A consultation to review specific air quality requirements will determine if this is indeed the ideal solution for you. In terms of air filtration, significant advancements that have been achieved with indoor air re-circulating technology now allows for the option of a completely mobile cleanroom that achieves full contaminant and climate control. A significant benefit of the air re-circulating option, especially for industrial users, is the elimination of pollutants into the environment, something we all benefit from. Furthermore, air recirculation technology will eliminate all of the start up costs associated with traditional vented systems, and will dramatically reduce annual operational costs. A completely mobile system will be extremely attractive to those users who will benefit from the ability to relocate their cleanroom within their facilities.

The exciting thing about retractable cleanrooms is the potential they have. After all, there is a large demographic out there who can benefit from them. Operationally, they have the potential of impacting many facets of a business; when you start to put a dollar value on the benefits, improvements, and efficiencies they offer, they make a lot of sense. In terms of potential uses, it certainly gets the creative juices flowing. From emergency quarantine centers to a whole host of manufacturing processes, retractable cleanrooms are a good fit when contamination control is a priority.  

16'H x 16'W x 123'L Retractable Cleanroom with 25,000CFM negative pressure filtration system. Courtesy of Duroair Technologies.
16'H x 16'W x 123'L Retractable Cleanroom with 25,000CFM negative pressure filtration system. Courtesy of Duroair Technologies.
For those of you who are considering this retractable option, research is your friend. Searching the Internet will provide you with a starting point for vendors. However, you'll certainly want to hone in on a partner that will invest the time and attention to fully understand your requirements and the challenges which have directed you to the retractable option. Just as important in this process is joining with a partner that is well educated in the area of contamination control. When working on projects of this scale, it is always recommended that you work with a full service partner and allow them to manage the complete process from design through to installation.

A shift of sorts is underway, and the perception of what a cleanroom looks like is changing. We live in a world of "smart TVs" and "smart phones,” so why not "smart cleanrooms"? The proposition is certainly an enticing one and it's hard to argue with the benefits retractable designs offer. Consequently, more and more companies are choosing them and their proposed uses are very creative indeed! Not to be overlooked when considering this growing market is the vision and forward thinking demonstrated by these companies. In much the same spirit that was demonstrated by Willis Whitfield, they are at the forefront of moving this industry into the future.

Cleanroom Cleaning and Disinfection: Eight Steps for Success

Cleanrooms in healthcare and pharmaceutical facilities must be kept in a state of microbiological control. This article outlines eight key steps for keeping a cleanroom clean.
Cleanrooms in healthcare and pharmaceutical facilities must be kept in a state of microbiological control. This is achieved in a number of ways, including the physical operation of Heating, Ventilation, and Air Conditioning (HVAC) systems, control of materials, properly gowned and trained personnel, and through the use of defined cleaning techniques, together with the application of detergents and disinfectants.
The object of cleaning and disinfection is to achieve appropriate microbiological cleanliness levels for the class of cleanroom for an appropriate period of time. Thus the cleaning and disinfection of cleanrooms is an important part of contamination control.1 This article examines the eight key steps to be followed, in relation to cleaning and disinfection, in helping to keep cleanrooms “clean.”
Step 1: Understanding cleaning and disinfection
Cleaning and disinfection mean different things and they are sometimes confused. Most importantly cleaning, using a detergent, must come before disinfection. Detergents are cleaning agents and are deployed to remove ‘soil’ (such as dirt, dust, and grease) from a surface.2 The removal of soil is an important step prior to the application of a disinfectant, for the greater the degree of soiling which remains on a surface then the less effective the disinfection step becomes.
Detergents generally work by penetrating soil and reducing the surface tension (which fixes the soil to the surface) to allow its removal (in crude terms, a detergent increases the ‘wettability’ of water).
A disinfectant is a type of chemical germicide which is capable of eliminating a population of vegetative microorganisms (in addition, some disinfectants are sporicidal).
Step 2: Selecting the most appropriate agents
Selecting the most appropriate cleaning and disinfectant agents is important. The cleanroom manager will need to be confident that the agents will work and are appropriate for the type of cleanroom. Care also needs to be taken as some agents are not compatible with each other.
In selecting detergents, it is important that:
a) The detergent is neutral and a non-ionic solution.
b) The detergent should be non-foaming.
c) The detergent should be compatible with the disinfectant (that is the residues of the detergent will not inactivate the disinfectant).
When selecting a disinfectant, points to consider are:3
a) To satisfy GMP regulations, two disinfectants should be used in rotation. While scientifically this may not be necessary, many regulatory agencies expect to see two different disinfectants in place. For this, the two agents selected should have different modes of activity.4 It may be prudent for one of the disinfectants to be sporicidal.
b) The disinfectant should have a wide spectrum of activity. The spectrum of activity refers to the properties of a disinfectant being effective against a wide range of vegetative microorganisms including Gram-negative and Gram-positive bacteria.
c) Ideally the disinfectant should have a fairly rapid action. The speed of action depends upon the contact time required for the disinfectant to destroy a microbial population. The contact time is the period of contact when the surface to which the disinfectant is applied must remain wet.
d) Residues from organic materials or detergent residues should not interfere with the disinfectant.
e) Disinfectants used in higher grade cleanrooms (like ISO 14644 classes 5 and 7) must be supplied sterile or be sterile filtered by the cleanroom operators.
f) The disinfectant should be able to be used at the temperature at which the cleanroom operates. If a cleanroom is a cold store then it needs to be checked whether the disinfectant will work at that temperature.
g) The disinfectant should not damage the material to which it is applied or some other measures should be taken. Many sporicidal disinfectants are chlorine based and will damage material like stainless steel unless the residue is wiped away after use.
h) The disinfectant should be safe for operators to use and meet local health and safety laws.
i) The disinfectant should be cost effective and be available in the required formats like trigger spray bottles or ready-to-dilute concentrates.
Step 3: Understanding types of disinfectants
There are a number of different types of disinfectant with different modes of activity and of varying effectiveness against microorganisms. Disinfectant action against the microbial cell include: acting on the cell wall, the cytoplasmic membrane (where the matrix of phospholipids and enzymes provide various targets), and the cytoplasm. Understanding the distinction between different disinfectants is important when selecting between non-sporicidal and sporcidial disinfectants (the division between non-oxidizing and oxidizing chemicals).5
Non-oxidizing disinfectants include alcohols, aldehydes, amphoterics, biguanide, phenolics, and quaternary ammonium compounds. Oxidizing disinfectants include halogens and oxidizing agents like peracetic acid and chlorine dioxide.
Step 4: Validating disinfectants
For pharmaceutical facilities, the disinfectants used must be validated. This involves laboratory testing and using either U.S. AOAC methods or European norms. Some of this testing can be carried out by the disinfectant manufacturer and some should be carried out in-house.
Disinfectant testing involves challenging the disinfectant solution (as a suspension test) and challenging different surface materials with disinfectant and a range of different microorganisms including isolates from the facility.6
Step 5: Factors which affect disinfectant efficacy
There are a number of factors which affect how well disinfectants work in practical situations, and it is important to understand these in order for the cleaning program to be effective. Factors affecting disinfectant efficacy include:
a) Concentration: this is the optimal dilution of the disinfectant to give the greatest microbial kill.7 It is a fallacy that by making the concentration of a disinfectant greater it will kill more bacteria when it is the validated concentrations which work.
b) Time: The time that the disinfectant is used for is important. Sufficient time is needed for the disinfectant to bind to the microorganism, traverse the cell wall, and to reach the specific target site for the disinfectant’s particular mode of action.
c) The numbers and types of microorganisms, in terms of some disinfectants being less effective against certain species which are more resistant. If high numbers of bacterial spores are isolated, a nonsporicidal disinfectant will be ineffective.
d) Temperature and pH: each disinfectant has an optimal pH and temperature at which it is most effective. If the temperature or pH are outside this optimal range, then the rate of reaction (log kill over time) is affected.
Step 6: Cleaning materials
The cleaning materials used to apply disinfectants and detergents must be appropriate. The materials must be able to apply an even layer of each agent. For disinfectants and detergents used for floors, surfaces, and walls in sterile manufacturing areas, these must be applied using materials which are cleanroom certified and nonparticle shedding (non-woven and lint-free).
Step 7: Cleaning techniques
The cleaning and disinfection techniques are important. If detergents and disinfectants are not used in the correct way, areas will not be cleaned effectively and unduly high levels of microbial contamination will remain as the disinfectant will not penetrate layers of dirt.
Defined cleaning and disinfection steps must be in place, such as:8
  • Sweeping away dust and debris (if applicable).
  • Applying a detergent solution through wiping or mopping.
  • Ensuring that the detergent has dried.
  • Applying a disinfectant solution through wiping or mopping.
  • Keeping the surface wet until the contact time has elapsed.
  • Removing disinfectant residue through wiping or mopping with water for injections or 70% IPA.
Detergents and disinfectants for use on surfaces (walls, floors) must be applied using the double or triple-bucket system to avoid cross contamination. Both of these techniques involve using a bucket of disinfectant and a bucket of water. In the “two-bucket” technique there is a “wringer” (for the mop) over the bucket of water. In the “three-bucket” technique there is a third bucket, empty except for having a wringer mounted over it.
Step 8: Monitoring cleaning and disinfection efficiency
The main test of how well a cleaning and disinfection program is working is through the results from the environmental monitoring of cleanrooms. This is assessed by viable microbiological sampling of surfaces using techniques like contact plates and swabs. If the results obtained are not within recommended action levels or company in-house limits, this suggests a problem with either: the cleaning and disinfectant agents, the frequency of cleaning, or the techniques used. Conversely, if the results are satisfactory, the cleanroom manager can have confidence that the cleanroom is indeed “clean.”
This article has presented an eight step approach to keeping cleanrooms clean. The best practice advice presented in this article should be captured into a Standard Operating Procedure and the staff members that need to be aware of it should be properly trained. Once a facility is under control, the most important thing is to continue to clean and disinfect using the correct techniques and the correct agents at defined frequencies. That way, cleanrooms will stay clean.
  1. Sutton, S.V.W. ‘Disinfectant Rotation in a Cleaning/Disinfection Program for Cleanrooms and Controlled Environments,’ in Manivannan, G. (Ed.), Disinfection and Decontamination: Principles, Applications and Related Issues, CRC Press 2008, pp165-174
  2. Bessems, E.: ‘The effect of practical conditions on the efficacy of disinfectants,’ International Biodeterioration and Biodegradation, 41, 1998, pp177-183
  3. Sandle, T.: Selection and use of cleaning and disinfection agents in pharmaceutical manufacturing in Hodges, N and Hanlon, G. (2003): Industrial Pharmaceutical Microbiology Standards and Controls, Euromed Communications, England
  4. Block, S. Disinfection, Sterilisation and Preservation, Third Edition, 1977, Philadelphia: Lea and Febiger
  5. McDonnell, G. and Russell, A.: ‘Antiseptics and Disinfectants: Activity, Action and Resistance,’ Clinical Microbiology Reviews, Jan. 1999, pp147-179
  6. Vina, P., Rubio, S. and Sandle, T. (2011): ‘Selection and Validation of Disinfectants,’ in Saghee, M.R., Sandle, T. and Tidswell, E.C. (Eds.) (2010): Microbiology and Sterility Assurance in Pharmaceuticals and Medical Devices, New Delhi: Business Horizons, pp219-236
  7. Russell, A. D.: ‘Assessment of sporicidal efficacy,’ International Biodeterioration and Biodegradation, 41, 1998, pp281-287
  8. Baird R Cleaning and Disinfection in the hospital pharmacy in Collins et al Disinfectants, their use and evaluation of effectiveness. Society Applied Bacteriology TS16 p154 1981.