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DuPont Personal Protection

Technical Data

Standards: IEST

Federal Standard 209E
Institute of Environmental Sciences and Technology (IEST)
Helmke Drum
Releasable Particles (Vacuum) Test
Body Box

Federal Standard 209E

Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones

This standard establishes classes of air cleanliness for cleanrooms and clean zones based on airborne particles.

The class limits give concentrations of airborne particles with sizes equal to and/or larger than size .5 microns per cubic foot.

Institute of Environmental Sciences and Technology (IEST)

The IEST-RP specifies three methods for evaluating the cleanliness of protective garments:

1. The Helmke Drum

2. The Releasable Particles (vacuum test designed for reusable garments)

3. The Particle Containment Test (Body Box)

Note: End-users normally use .5 size microns & larger as the basis for evaluation.

Helmke Drum Method:

Garments to be tested are placed in a rotating drum that is open at one end and tumbled to release particulate matter from the fabric. An automatic particle counter is used to sample the air within the drum to determine the particle density level of the air. This density level is then compared with Table II to determine a relative class for the particular type of garment.

Releasable Particles (Vacuum) Test Method

The vacuum test measures the particles that are released from the outer surface of the garment fabric. The surface is vacuumed and the released particles are caught on a filter, visually measured, and counted under a microscope by a technician. This method does not address garment performance and only measures surface contamination. It is not an analytical method, it relies on a technician to count and size particles.

'Body Box' Method

The Particle Containment (Body Box) method has been accepted by more cleanroom users to qualify the relative cleanliness of a garment system. By testing the particle shed and particle containment of the entire garment system, the body box provides more reliable data about overall performance.

During the body box test, a subject is placed in a Class 10 room and performs a series of activities during a ten minute test period. The activities include arm extensions for three minutes, walking for three minutes and doing five deep knee bends in one minute. These activities are separated by one minute intervals of standing still. The data is reported as the average number of particles .5 micron and larger counted per minute during the ten minute test period.