Instruction manual

SM425 INSTRUCTION MANUAL 4.0 PIPING
Figure 4-13 Detector with Pressure Compensation
Ensure that process gas does not flow into the probe.
Valve operation
1. For safety, shut down the process before installing the detector. It is especially dangerous if the
process internal pressure is high.
2. Before starting instrument air flow, completely shut the stop valve in front of the reference gas
outlet.
3. Check the reference gas outlet is not blocked.
4. Adjust the instrument air pressure to higher than process internal pressure.
5. Completely open the stop valve in front of the reference gas outlet and, after turning on
instrument air flow, start up the process. As process internal pressure rises, verify instrument air
continues to flow. Adjust the valve or increase supply pressure if necessary.
6. After process internal pressure stabilizes, adjust flow.
7. If the process is shut down, stop instrument air flow and completely shut the stop valve in front of
the reference gas outlet. Reference gas may be left flowing.
- If possible, to prevent process gas from entering the detector and damaging the zirconia cell, do not
stop instrument air flow.
- Connect the calibration gas stop valve directly to the detector inlet. If there is piping between the
detector and the valve, condensation may damage the sensor by thermal shock when calibration gas is
introduced.
Figure 4-14 illustrates an example of System 2 using a detector with pressure compensation.
78 42500001 REV A