KROHNE BM 70A EEx EN User Manual
Page 10
07/2010 - 4000662402 MA BM70x-Ex-AD-R02-en
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To calculate the maximum allowable tank pressure, where flange and product temperatures are
> 100°C, use the following formula and/or table for the flange system WS:
PB = 16 bar – 0,3 * ( T
flange, product
– 100 °C )
Tank pressure PB as a function of the flange
or product temperature
Flange temperature / product temperature
[°C]
Tank pressure
[bar]
100
16
110
13
120
10
130
7
140
4
150
±1
3.2.1.3.
Tank connections
Allocation of tank connections to categories and zones:
Tank connection
Standard
Category
Tank Zone
Flange
DIN 2501, ANSI, JIS, BS
1G or 2G
0 or 1
Threaded
DIN ISO 258
2G
1
Sanitary
DIN 11851
2G
1
3.3. Temperature classes, complete device
3.3.1.
General
In terms of maximum surface temperatures, level measuring devices are exposed to three heat
sources:
Ambient temperature Ta
Electric power loss PV
Product temperature Tp
Accordingly, at a given maximum ambient temperature (Ta < 55°C) and a given maximum loss power,
we obtain maximum surface temperatures as a factor of the product temperature. For that reason, the
devices are not allocated to any specific temperature class; rather, the temperature class of the
devices is a function of the actual product temperature.