Instruction manual

SM425 INSTRUCTION MANUAL 4.0 PIPING
- The stop valve should be connected directly to the detector. If any piping is present between the
detector and the stop valve, water may condense in the pipe. This may cause damage to the sensor by
thermal shock when the calibration gas is introduced. The stop valve should be closed except during
calibration.
- Piping the reference gas is recommended if a high-temperature detector is used (the sample gas
temperature is 700°C or higher). For other detectors, piping is required if the air around the detector is not
clean.
- The reference gas should have an oxygen concentration identical to that of fresh air (21%).
- When a high-temperature detector is used, the sample gas is vented into the surrounding air.
• If a high-temperature detector is used and no piping can be installed for the reference gas, vent
the exhaust of the high-temperature probe adapter away from the vicinity of the detector using an
exhaust pipe (see Section 1.18.4, Figure 4-6 Exhaust pipe). Otherwise the requirements for
reference gas may not be met.
• If a high-temperature detector is used and the process gas is under negative pressure, connect
an auxiliary ejector to the sample gas exhaust port of the high-temperature probe adapter (see
Section 1.18.4, Figure 4-3 Mounting the auxiliary ejector).
• If a high-temperature detector is used and the pressure of the process gas is 0.49 kPa or higher,
it is recommended a needle valve (throttle) be used in the sample gas exhaust of the high-
temperature probe adapter (see Section 1.18.4, Figure 4-4).
- The throttle valve is used to lower the sample gas temperature below 700°C. If the process is at high
temperature and pressure, the sample gas temperature may not fall to below 700°C before it reaches the
detector.
If the sample gas temperature is lowered too much, condensation may be produced in the high-
temperature probe adapter. During wintertime it is recommended the probe adapter be protected with an
insulating material to avoid condensation forming (see Section 1.18.4, Figure 4-5).
Refer to Section 1.11.2 for maintaining temperatures within the high-temperature probe adapter.
4.1.1 Parts Required for Piping in System 1
Verify the parts listed in Table 4-1 are ready.
68 42500001 REV A