1B-12 / DP Transmitters 2808B
An on-site, zero test signal for calibration purposes can be generated by opening the bypass
valve and closing both shutoff valves. Calibration information will be found in Section 3.
Figure 1B-9 - Gas, Horiz, Pipe Figure 1B-10 - Gas, Vert. Pipe
Steam Application. When measuring steam pressure, the maximum temperature of the
Transmitter's electronic circuitry must be strictly observed. Temperatures above the
specified limit (see topic 2.1, Environmental Temperature) will cause output errors and
possibly result in damage to the Transmitter. One method of protecting the Transmitter
can be achieved by installing an extended, liquid-filled connecting line as shown in Figures
1B-11 and 1B-12. The liquid functions as a buffer and prevents live steam from entering the
transmitter.
When using liquid-filled system, the connecting line must be installed in a descending step
so that the Transmitter is below the level of the process pipe tap and filling tee; this slope
will maintain the liquid in the connecting line and prevent it from being drawn into the
process pipe. Liquid-filled lines must also be properly filled and bled, and checked on a
regular basis.
Figure 1B-11 - Steam Process, Horiz. Pipe Fig. 1B-12 - Steam Process, Vert. Pipe
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