MIL-STD-1330D(SH)
w/ Change 1
5.1.1 Structure.
5.1.1.1 Class A. Class B requirements shall apply. Additionally, best commercial practices shall be employed in the use of materials, construction, filtration, clothing, personnel, and temperature, pressure, and humidity control to achieve an airborne particulate cleanliness level equivalent to ISO 14644-1 and 14644-2, Class 8, or better. Refer to MIL-HDBK-407 for additional guidance.
5.1.1.2 Class B.
a. A permanent enclosure comprised of a rigid frame with clearly defined walls, ceilings, and floor, all adequate to prevent the entry of contamination from the surrounding environment.
b. The surface of the walls, ceiling, and floor shall be fabricated or coated with material that minimizes attraction of dirt and is easily cleaned. Refer to MIL-HDBK-407 for additional guidance.
c. Where dirt may be brought into the clean area, preventative measures such as anterooms, shoe covers, or tack mats shall be employed. Anterooms should provide for changing and stowing of clothing, examination of tools and equipment, and personnel access to the clean area. Washing, toilet facilities, and storage facilities for maintenance of equipment should be provided in the immediate area where desirable.
d. Furnishings and equipment such as work benches, chairs, and racks shall be constructed and finished with materials that will not produce dust or particulate as a result of chipping, flaking, or rusting. Paint should be hard and non-flaking or non-chalking. Furnishings likely to be abraded or bumped should be constructed of either stainless steel or non-fracture type plastic. Refer to MIL-HDBK-407 for additional guidance.
e. Work that produces airborne dust, dirt, or particulate should not be performed in a cleanroom. Welding and brazing shall not be performed in a cleanroom.
5.1.1.3 Class C. Air borne debris or contamination resulting from work accomplished in the controlled area shall be eliminated before redesignation as a controlled area. Depending on the time and work involved for a particular operation, a controlled area shall be one of the following:
a. Clean space located or set up adjacent to areas which are non-contaminant producing.
b. Clean tent or partitioned and covered area. The clean-tent shall be established by taping clean, unused, polyethylene plastic sheets in accordance with MIL-PRF-22191, Type I, or equal, on the deck, overhead, and vertical areas for a distance of 3 to 4 feet around the area concerned. The outside surfaces of exposed materials within the confined area shall be cleaned to remove dust, oil, dirt, and other foreign material. Air movement within the confined area shall be held to minimum.
c. Clean glove box or isolation box with a clean atmosphere. The glove box is a temporary enclosure surrounding the work area and sealed from the outside atmosphere. Work is accomplished through plastic gloves sealed to the box walls.
d. A sleeve, with a clean, dry, nitrogen supply or equally clean, dry, air supply.
5.1.2 Maintenance.
5.1.2.1 Class A. Class B requirements shall apply. Additionally, when specified, a particle count of the laminar flow benches and each clean area should be accomplished daily.
5.1.2.2 Class B.
a. Complete cleaning and wipe-down of equipment, tools, workbenches, counters, table tops, and fixtures with detergent such as NID specified in 4.3.3, or commercial equivalent, and vacuuming and mopping of the floor shall be accomplished at the end of each 8 hours of operation and prior to use if greater than 24-hours has passed since the cleanroom was last used.
b. Complete cleaning and wipe-down of the walls, floors, and ceiling with detergent such as NID specified in
4.3.3, or commercial equivalent, shall be accomplished monthly.
c. The average air temperature and average humidity in a cleanroom shall be measured daily. d. Air filters shall be cleaned or replaced at regular intervals.
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