Ground support equipment (GSE) cleaning procedures

General cleaning Guidelines

It is recommended you read the list of approved and banned materials first. For computers and associated equipment, please let the cleanroom manager know you plan to bring these items in and if you require LAN access from within the cleanroom. Before entering any part of the cleanroom, pre-clean the items with IPA and fibre free wipes. Detailed cleaning instructions will follow this general guideline.
For equipment such as computers, keyboards etc, vacuum clean using a general purpose vacuum cleaner. Particular attention should be paid to the ventilation ports.This pre clean should be done external to the cleanroom and anteroom and items should be covered with clean bagging material, but not of cleanroom quality. As a guide, notebook computers are preferred to desktop computers (although this is not always practical) not only due to size but also from a cleanliness aspect. Clean all equipment at an external location to the cleanroom. This equipment can then be bagged to minimise contamination.
Small metallic items (screws, nuts, washers) and non metallic items that are safe to use with solvents must be cleaned using the ultra sonic cleaner located in the chemical lab. Upon entering the cleanroom anteroom remove from packaging and visually inspect for any obvious signs of contamination that may have been missed and re-clean if necessary. The best way to visually inspect any item is to view the item surface at a five degree angle with good background lighting
When cleaning items using wipes provided in the anteroom do the following:

• Fold the wiper in half and then fold in half again.
• Now apply IPA to the folded wiper
• The maximum number of wiping actions per fold should be no more than four times.
• Wipe the surface in a single direction
• Once four wiping actions have been done, use the other folds to continue cleaning as above procedure.

If the person who performs the cleaning operation then goes into the cleanroom, a new pair of cleanroom gloves must be fitted. The clean item can then be taken into the cleanroom and any necessary final cleanup can be done within the cleanroom as described above using wipers and IPA provided. (see note 1 and note 2)
NOTE1: There are two sets of solvent carriers and solvent wash bottles in the cleanroom. The first set is located in the anteroom which is used for item cleanup and the other is located within the cleanroom. The second set located within the cleanroom is ONLY for use on optics and flight instruments/hardware. The solvent used in the second set is UVASOL and is spectroscopic grade propan-2-ol (IPA). Do not use this second set for general/surface cleaning. When using the spectroscopic grade IPA ensure that the nozzle of the wash bottles do not come into contact with the wiper or any other surface as cross contamination will occur if this happens
NOTE2: There are two grades of wipers used in the cleanroom. General purpose grade wipers (non woven polyester) are available in the Anteroom. These wipers should be used for item and general cleanup and should be recycled by disposing of them in the cleanroom laundry basket and NOT in the refuse bins. The second wiper is of a better quality (sealed edge non woven polyester with low particulate and extractable's). These wipers are available within the cleanroom in dispensers and should be used on flight quality instruments and hardware.

Monitoring of processes and equipment

When bringing equipment into the cleanroom, ensure that you observe the following:
All cleanroom users should ensure that they consult the cleanroom manager before they bring any equipment and processes into the cleanroom.This cannot be stressed enough! The monitoring of equipment and processes going into the cleanroom is an important part of the general contamination control of the cleanroom. If bringing equipment or processes into the cleanroom ensure that you follow the detailed procedures listed below.
General tooling such as screwdrivers, nut drivers, rulers, vernier calipers etc. do not need to be bought into the cleanroom as there is a fully stocked cleanroom tool cabinet for all cleanroom users benefit. The tooling in the cabinet is for cleanroom use only and must never be removed from cleanroom. When using cleanroom tooling ensure that they are put back into the cabinet after use. Do not leave tooling lying about as this means that other users will not be able to use them. If you are a visitor and you need specialised tooling ensure that  you contact the cleanroom manager to confirm whether the tooling is available.
If you are bringing a process into the cleanroom ensure you have done a risk assessment on the process and you have discussed this with the cleanroom manager. Under no circumstances may any process go into the cleanroom unless it has been discussed with the cleanroom manager, again this is a monitoring activity to aid in cleanroom contamination control and for Health and Safety reasons.

Detailed Cleaning procedures

Introduction

In order to meet project contamination cleanliness requirements, ground support equipment (GSE) used in clean areas at MSSL for flight hardware integration and testing needs to be cleaned at regular intervals. This is to ensure that surface contamination levels are minimised and the possibility of contamination redistribution from the GSE to the flight hardware is significantly reduced.

Required equipment

• Isopropyl Alcohol (IPA): Analar grade for course and intermediate cleaning and spectro grade for precision cleaning.
• Cleanroom Wipes: Lint-free Polyester
• Vacuum Cleaner: HEPA-filtered for precision cleaning
• Acetone: Analar grade for course and intermediate cleaning and spectro grade for precision cleaning
• Cleanroom Swabs: Woven Polyester
• Compressed Air or Nitrogen, filtered for particles to 0.5 micron
• White light source (100W)

Before use in a controlled clean area, GSE must be cleaned and inspected for visible cleanliness. GSE cleaning should be performed to visibly clean � sensitive level (VC-S) as defined in MSSL/PA/PS/Q012 �Procedure for verifying surfaces to a visibly clean level�. To achieve this surface cleanliness standard, GSE cleaning should be performed in three stages as defined below:

Course cleaning - General

Course cleaning can be performed in non clean areas (workshop, office etc). The idea is to remove the bulk of contaminants from the hardware. Nitrile gloves should be worn during course cleaning

Intermediate cleaning - General

Intermediate cleaning should be performed in the anteroom. Particular attention should be paid to surfaces, crevices, corners, vents etc and these should be cleaned using appropriate solvents or detergents. A more thorough inspection of all surfaces is required at this stage. Cleanroom wipes and nitrile gloves should be worn while performing intermediate cleaning.

Precision cleaning - General

Precision cleaning should be performed inside the cleanroom but away from flight hardware (ideally at entrance to cleanroom). Spectro grade solvents should be used and polyester cleanroom wipes. Cleanroom dress code of mask, hood, cleanroom bunny suit, overshoes and nitrile gloves should be observed. A methodical and thorough surface inspection should be carried out as defined in MSSL/PA/PS/Q012 �Procedure for verifying surfaces to a visibly clean level� to a VC-S level after cleaning.

Cleaning procedures
 Course cleaning

• Determine the surface sensitivity to handling and solvents. If the surface is sensitive to IPA or acetone, use filtered critical neutral detergent. If the surface is sensitive to handling, limit or eliminate vacuum use and handling as necessary to prevent GSE damage.
• If computing equipment is to be brought into clean areas laptop devices are preferred. If this is not possible desktop computers should be thoroughly cleaned inside and outside the casing paying particular attention to exhaust fans from the power supply.
• Computer monitors should be thoroughly vacuumed paying particular attention to the monitor vents prior to cleaning procedure below.
• Computer keyboards should be turned upside down and a jet of clean filtered compressed air or nitrogen directed between the keys prior to cleaning procedure listed below.
• Remove loose particles from the GSE by thoroughly vacuuming all surfaces, including holes, crevices, and corners, with a vacuum cleaner. This step should not be performed for items sensitive to handling. Minimise direct nozzle contact with GSE surfaces and continue until no particles are visible on GSE surfaces.

Intermediate cleaning

• Lightly dampen a cleanroom wipe with IPA (Analar grade or equivalent). Do not saturate the wipe or dip the wipe in the solvent container.
• Clean the GSE surface with the IPA dampened wipe, wiping the surfaces in a unidirectional manner. Do not overlook crevices, corners, or holes. If necessary, lightly dampen a swab with IPA and use the swab to clean recessed areas. Clean recessed surfaces with the swab by rotating the swab over the surface. During cleaning, fold the wipe to expose a clean surface or replace with a new wipe if the wiping surfaces become contaminated. Replace swabs when visibly contaminated. Lightly dampen each new wipe surface or swab with IPA and continue cleaning. Repeat until GSE surfaces do not display visible contamination.
• If solvent remains on any GSE surfaces, particularly blind holes or other recesses, dry the surfaces completely with filtered, oil-free GN 2 or air. Regulate the gas flow as necessary to prevent solvent splashing and damage to GSE surfaces. After solvent wiping, inspect surfaces for visible cleanliness as defined in MSSL/PA/PS/Q012.01 �Procedure for Verifying Surfaces to a Visibly Clean Level�
• If visual inspection reveals surface contaminants, repeat the solvent wiping procedure above and re-inspect. If contamination still remains visible after solvent wiping, repeat the solvent wiping procedure with acetone substituted for IPA. Before using acetone, however, verify that it will not degrade the materials undergoing cleaning. If contaminants remain visible after using acetone, contact the contamination control manager (CCM).

Precision cleaning

• Lightly dampen a cleanroom wipe with spectro grade IPA. Do not saturate the wipe or dip the wipe in the solvent container.

• Clean the GSE surface with the spectro grade IPA dampened wipe, wiping the surfaces in a unidirectional manner. Do not overlook crevices, corners, or holes. If necessary, lightly dampen a swab with IPA and use the swab to clean recessed areas. Clean recessed surfaces with the swab by rotating the swab over the surface. During cleaning, fold the wipe to expose a clean surface or replace with a new wipe if the wiping surfaces become contaminated. Replace swabs when visibly contaminated. Lightly dampen each new wipe surface or swab with IPA and continue cleaning.
• If solvent remains on any GSE surfaces, particularly blind holes or other recesses, dry the surfaces completely with filtered, oil-free GN 2 or air. Regulate the gas flow as necessary to prevent solvent splashing and damage to GSE surfaces.
• After solvent wiping, inspect surfaces for visible cleanliness as defined in MSSL/PA/PS/Q012 �Procedure for Verifying Surfaces to a Visibly Clean Level�. The surface cleanliness level should be VC-S. A white light source (100W) can be used to aid inspection. Repeat above cleaning procedure until GSE surfaces do not display visible contamination.
• All cleaned GSE cables can then be sleeved in Llumalloy bagging. Sleeve ends should be sealed with clean cable ties or Kapton tape.

Note: Depending on project contamination control requirements certain GSE may require cleaning to a more stringent level such as VC-HS. The above procedure can be adapted to suit this requirement by substituting the appropriate inspection procedure as defined in MSSL/PA/PS/Q012. Cleaning methods will remain the same.

clean room standards

The cleanroom classifications given in the earlier 209 versions are shown in Table 2. In the new 209E the airborne concentrations in the room have been given in metric units, i.e per m^3 and the classifications of the room defined as the logarithm of the airborne concentration of particles ³ 0.5 m m
e.g. a Class M3 room has a particle limit for particles ³ 0.5 m m of 1000/m^3. This is shown in Table 3.

Table 2 Federal Standard 209D Class Limits

CLASS	MEASURED PARTICLE SIZE (MICROMETERS)
	0.1	0.2	0.3	0.5	5.0
1	35	7.5	3	1	NA
10	350	75	30	10	NA
100	NA	750	300	100	NA
1,000	NA	NA	NA	1,000	7
10,000	NA	NA	NA	10,000	70
100,000	NA	NA	NA	100,000	700

Table 3 Federal Standard 209E Airborne Particulate Cleanliness Classes

Class Name		Class Limits
		0.1m m		0.2m m		0.3m m		0.5m m		5m m
		Volume Units		Volume Units		Volume Units		Volume Units		Volume Units
SI	English	(m^3)	(ft^3)	(m^3)	(ft^3)	(m^3)	(ft^3)	(m^3)	(ft^3)	(m^3)	(ft^3)
M 1		350	9.91	75.7	2.14	30.9	0.875	10.0	0.283	--	--
M 1.5	1	1 240	35.0	265	7.50	106	3.00	35.3	1.00	--	--
M 2		3 500	99.1	757	21.4	309	8.75	100	2.83	--	--
M 2.5	10	12 400	350	2 650	75.0	1 060	30.0	353	10.0	--	--
M 3		35 000	991	7 570	214	3 090	87.5	1 000	28.3	--	--
M 3.5	100	--	--	26 500	750	10 600	300	3 530	100	--	--
M 4		--	--	75 700	2 140	30 900	875	10 000	283	--	--
M 4.5	1 000	--	--	--	--	--	--	35 300	1 000	247	7.00
M 5		--	--	--	--	--	--	100 000	2 830	618	17.5
M 5.5	10 000	--	--	--	--	--	--	353 000	10 000	2 470	70.0
M 6		--	--	--	--	--	--	1 000 000	28 300	6 180	175
M 6.5	100 000	--	--	--	--	--	--	3 350 000	100 000	24 700	700
M 7		--	--	--	--	--	--	10 000 000	283 000	61 800	1 750

With a little thought it can be appreciated that the airborne contamination level of a given cleanroom is dependent on the particle generating activities going on in the room. If a room is empty, a very low particle concentration can be achieved, this closely reflects the quality of air supplied by the high efficiency filter. If the room has production equipment in it and operating, there will be a greater particle concentration but the greatest concentrations will occur when the room is in full production. The classification of the room according to FS 209D may therefore be carried out when the room is:
(a) as built, ie complete and ready for operation, with all services connected and functional but without production equipment or operating personnel.
(b) at rest, ie complete, with all services functioning and with equipment installed and operable or operating, as specified but without personnel in the facility.
(c) operational, ie in normal operation, with all services functioning and with equipment and personnel, if applicable, present and performing their normal work functions in the facility.
Federal Standard 209 is a document which mainly gives information on the airborne particle limits that are required to specify the airborne quality of cleanrooms and also gives the methods used to check what concentrations are present. It does not give any information on how a cleanroom should be operated. This information had been included in a series of Recommended Practices which are written by the same Institute as has written the Federal Standard 209, namely the Institute of Environmental Sciences. Some of the RP's which are of particular interest to those who test and run cleanrooms are discussed later in this document. 
 

British Standard 5295:1989

This standard is available from:
B S I Standards
389 Chiswick High Road
London W44 AL
Tel 0181 996 9000
Fax 0181 996 7400
The British Standard is in five parts. These are:
Part 0 - General introduction and terms and definitions for cleanrooms and clean air devices. (4 pages)
Part 1 - Specification for cleanrooms and clean air devices. (14 pages)
Part 2 - Method for specifying the design, construction and commissioning of cleanroom and clean air devices. (14 pages)
Part 3 - Guide to operational procedures and disciplines applicable to cleanrooms and clean air devices. (6 pages)
Part 4 - Specification for monitoring cleanrooms and clean air devices to prove continued compliance with BS 5295. (10 pages)
The contents of the above parts are as follows:
Part 0 - 'General introduction, terms and definitions for cleanrooms and clean air devices'
The definitions have been drawn together and presented in this section. This part also provides a basic introduction to the main parts of the standard, particularly for those unfamiliar with cleanrooms or the standard itself.
Part 1 - 'Specification for cleanrooms and clean air devices'
The Standard contains ten classes of environmental cleanliness. Shown in Table 4 are the classes given in the standard. All classes have particle counts specified for at least two particle size ranges to provide adequate confidence over the range of particle size relevant to each class.
Some classes of rooms, except for 0.3 m m particles, have an identical specification. For example, Class F is equivalent to Class E except for the 0.3 m m particle specification. This is deliberate, as many users, e.g. pharmaceutical manufacturing, do not wish to be associated with the small particle technology that is not appropriate to their industry.

Table 4 BS 5295 Environmental cleanliness classes
 

	Maximum permitted number of particles per m^3 (equal to, or greater than, stated size)					Maximum floor area per sampling position for cleanrooms (m^2)	Minimum pressure difference*
Class of environmental cleanliness	0.3 m m	0.5 m m	5 m m	10 m m	25 m m		Between classified areas and unclassified areas (Pa)	Between classified area and adjacent areas of lower classification (Pa)
C	100	35	0	NS	NS	10	15	10
D	1 000	350	0	NS	NS	10	15	10
E	10 000	3 500	0	NS	NS	10	15	10
F	NS	3 500	0	NS	NS	25	15	10
G	100 000	35 000	200	0	NS	25	15	10
H	NS	35 000	200	0	NS	25	15	10
J	NS	350 000	2 000	450	0	25	15	10
K	NS	3 500 000	20 000	4 500	500	50	15	10
L	NS	NS	200 000	45 00	5 000	50	10	10
M	NS	NS	NS	450 000	50 000	50	10	NA

 

BS 5295:1989 identifies three states of operation similar to FS208E:

• as built - on completion, prior to moving in
• unmanned - operational but not in use
• manned - in full operational use
• Also given in the specification of Part 1 are other requirements for cleanrooms to comply with. These are:
• minimum pressure difference between the cleanroom and adjacent areas (see Table 4)
• filter installation test leakage
• freedom of leakage from construction joints or openings

Testing to satisfy the requirements of Part 1 of the British Standard is discussed later in this document in that section which deals with the testing and validation of cleanrooms.
Part 2 - 'Method for specifying the design, construction and commissioning of cleanrooms and clean air devices'
A major consideration in the rewrite of BS 5295 was to ensure its usefulness as a purchase and operational specification and as supporting documentation to a contract. Part 2 has therefore been restructured into a format which enables a purchaser to specify what type of room or device is required and, where relevant, how it is to be achieved. To assist with its use as part of contractual documentation it has been given specification status, i.e. it is mandatory.
Part 3 - 'Guide to operational procedures and disciplines applicable to cleanroom and clean air devices'
This incorporates guidance for those drawing up procedures for personnel, operations, cleaning, garments and garment laundering.
Part 4 - 'Specification for monitoring cleanrooms and clean air devices to prove continued compliance with BS 5295: Part 1'
Cleanroom and clean air equipment standards have for many years defined classes of cleanliness and how they are to be assessed. However there has never been any requirement to test a cleanroom at any point in its often very long lifetime, other than at the time of handover from supplier to purchaser. Once accepted from the supplier, the facility then repaid its capital cost, over a life span of ten to twenty years, sometimes without ever being tested. Yet over this period customers were provided with products which were stated to be 'produced under Class X'. This can no longer be the case.
The tests specified are those contained in Part 1, thus providing a continuity back to the original purchase specification. The intervals between tests are related to the class of room or device and are given later in this manual in that section relating to the validation and testing of cleanrooms.

ISO Standard

Because of the large number of cleanroom standards produced by individual countries it is very desirable that one world-wide standard of cleanroom classification is produced. The International Standards Organisation is producing such a document. Because of the number of countries involved and the problems with translation it may be over a year before it is published. However, it is unlikely that it will be different from table 5.

Table 5. Selected ISO 209 airborne particulate cleanliness classes for cleanrooms and clean zones.

 

numbers (N)	Maximum concentration limits (particles/m^3 of air) for particles equal to and larger than the considered sizes shown below
	0.1m m	0.2m m	0.3m m	0.5m m	1m m	5.0m m
ISO 1	10	2
ISO 2	100	24	10	4
ISO 3	1 000	237	102	35	8
ISO 4	10 000	2 370	1 020	352	83
ISO 5	100 000	23 700	10 200	3 520	832	29
ISO 6	1 000 000	237 000	102 000	35 200	8 320	293
ISO 7				352 000	83 200	2 930
ISO 8				3 520 000	832 000	29 300
ISO 9				35 200 000	8 320 000	293 000