Rotem DRM-3000 - Response Times for the GM Tubes; Automatic Range Switching for the DRM-3000

Page | 13 DRM-3000 Operating Manual
6.2 Response Times for the GM Tubes
Table 1
Response Time for Small Changes
Table 2
Fast Response Time
Radiation Field
Range [mR/h]
Response
Time
[sec.]
Radiation field
[mR/h] from
to/above
Response
Time
[sec.]
< 0.5 45 0.05 1.0
 2
0.5 - 1.5 30 0.5 3.0
 2
1.5 - 2.5 20 1.5 5.0
 2
2.5 - 6 10 2.5 12
 2
6 - 12 6 6 20
 2
12 - 24 4 12 40
 2
20 - 60 3 20 60
 2
60 - 800 2 1 R/h 2 R/h
 2
0.6 - 1.2 R/h 5 2 R/h 2.6 R/h
 2
1.2
-
2 R/h
4
2
-
3 R/h
3
3
-
10 R/h
2
–
3
> 10 R/h
 2
If the radiation field measured by the meter increases significantly, the response time will be
 2 sec. as seen in Table 2. In other cases the response time is according to Table 1.
For example:
For a radiation field increase from 2.5 mR/h to 12 mR/h, the response time will be  2 sec.
For radiation field fluctuations between 2.5 mR/h and 6 mR/h, the response time will be 10 sec.
4.1.1 Automatic Range Switching for the Wide Range Detector
Both the Internal and external detectors include two GM Tubes:
Low range - ZP-1201 (or equivalent), and high range ZP-1301 (or equivalent).
In a field of 0.01 mR/h to 1,500 mR/h both GM tubes are connected and the field is measured
by the low range GM tube. If the radiation field is higher than 1,500 mR/h, the low range
detector is disconnected, and the radiation field is measured by the high range GM tube.
The switching between the low and high range GM-Tube is performed at 1,500 mR/h when the
radiation field increases (low range detector is disconnected), and at 1,000 mR/h when the
radiation field decreases (low range detector is connected).