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
|