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Entry  Tue Sep 25 14:18:14 2012, Koji, Clean, General, Particle Counts 
    Reply  Mon Oct 1 16:06:55 2012, Koji, Clean, General, Particle Counts 
Message ID: 21     Entry time: Mon Oct 1 16:06:55 2012     In reply to: 20
Author: Koji 
Type: Clean 
Category: General 
Subject: Particle Counts 

1. It turned out that the particle counter MET ONE 227A at ATF shows
(particle count)/(0.1 ft^3)


This means that the numbers I saw previously should be multiplied by 10.
So the nominal class of the room was 5000.

2. As our GT-321s have no diffuser, I borrowed a diffuser from 227A.
The diffuser actually increases the count. We need to buy them.
All the measurments below are performed with the diffuser and calibrated in Count/ft^3.

3. Measured the particle level without the HEPA running.

With diffuser: [cnt/ft^3]

  GT-321 #1 GT-321 #2   227A
0.3um 152622 137511 -
0.5um  14706 14823   11860

Over Class 10000

4. The two HEPA fans are turned on at the speed "MED".

Basically no particles are detected in the HEPA booth.

With diffuser, inside of the HEPA booth:

  GT-321 #1 GT-321 #2  227A 
0.3um 0 0
-
0.5um 0 0 0

The particle level in the room (outside of the HEPA booth) is also improved

With diffuser, outside of the HEPA booth GT-321 #1:
0.3 um 18612
0.5 um   1728

5. The two HEPA fans are turned on at the speed "LOW".

Particle levels are still zero inside.

With diffuser, inside of the HEPA booth, GT-321 #1:
0.3 um 0
0.5 um 0

The particle level in the room (outside of the HEPA booth) is also improved
but the cleaning power for 0.3um seems degraded.

With diffuser, outside of the HEPA booth, GT-321 #1:
0.3 um 34488
0.5 um   1386

 

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