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Life Science Research
 

Clean Room Garments

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The procedure for sampling clean room garments requires that you draw filtered air through five designated 0.01 sq. ft. areas of a single thickness of the garment fabric at a rate of 14 liters per minute (L/min) for one minute per area. Loose particulate contaminants on or in the garment impinge on the surface of an Merck filter. Examine the filter under a microscope to determine the number of particles (>5 µm in diameter) removed from the garment.


Sampling Procedure
  1. Screw the 14 L/min flow-limiting orifice into the filter holder outlet and connect the holder to a vacuum source (of at least 55 cm Hg at 14 L/min) using a hose.
     
  2. Carefully place a Type AA black filter, grid side up, on the support screen in the filter holder base using clean forceps. Similarly place a Type SM white filter on top of the filter. Lock in place with the blue locking ring. When ready to sample, see step 3.
 Filter is centered on base of garment monitoring holder. The prefilter is placed onto the filter.
Filter is centered on base of garment monitoring holder. The prefilter is placed onto the filter.
  1. Place the outer surface of the test garment over the tapered (male) body of the holder. Secure the prefilter adapter assembly over the test portion of the fabric.
     
  2. Apply vacuum and sample with the same filter for a period of one minute for each of the five test areas. Be sure to turn vacuum off after each test.
     
  3. Open the filter holder, remove the sample filter, and place it on a PetriSlide™ device for subsequent counting. (Refer to Analysis Techniques section)
 Test garment secured between prefilter adapter section (right), and the filter holder (left).
Test garment secured between prefilter adapter section (right), and the filter holder (left).

Counting

For garment monitoring, it is customary to count and tabulate particles in two categories only:
  1. All particles with the major dimension greater than 5 µm.
     
  2. Fibers (longer than 100 µm with a length-to-width ratio exceeding 10:1).
Each garment sampling area is 0.01 sq. ft. as defined by the clean room monitoring filter holder. Five sampling areas, therefore, provide a garment sample of 0.05 sq. ft. Multiply the total filter count by 20, for example, for 5 sample areas and report results in terms of particles per sq. ft. and fibers per sq. ft. of garment.