Ametek CEM/Humox, Руководство пользователя

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3-2 | Thermox CEM/Humox Analyzer
Mounting the Wet and Dry CEM/O
2
Sensors
To get a percent moisture reading, the system calculates the difference between
a wet sample and a dry, conditioned sample. Both are measured using zirconium
oxide cells. The customer provided cooler dries the sample. Knowing the cooler
temperature setpoint or using the platinum 100 ohm RTD provided to measure the
cooler exhaust temperature, the residual moisture contained in the gas stream after
the cooler can be calculated and added to the moisture calculated from the wet and
dry O
2
readings (refer to Drawing 131-023-1 in the Appendix for RTD wiring detail).
The CEM/O
2
sensor enclosure is a NEMA 12 rated polyurethane coated carbon
steel cabinet that you mount to a wall. Figure 3-1 provides wall mounting dimen-
sions for the sensor. Provide at least six inches clearance above the sensor so you
can later replace the cell. The cell is replaced by lifting it through the top of the
sensor enclosure.
The sensor should be located as close to the sampling system as possible. The
ambient temperature must be in the range of -18 to 50°C (0 to 122°F). The sensor
relies on a convection principle to flow sample gas over the oxygen cell. Therefore,
it must be mounted vertically.
The Series 2000 Control unit is housed in a 19” rack. The two CEM/O
2
sensors are
located side by side. This setup eliminates long lengths of tubing and reduces the
delay time between the two sensors. A sample pump pulls the sample in through a
heated set of teflon tubes to maintain the sample temperature at 275°F. This keeps
the moisture in a vapor state. The same stream then splits – most of the sample goes
to the dry sample conditioning system and then to the Thermox CEM/O
2
analyzer
and the other analyzers in the CEM system. The other part, still wet and uncondi-
tioned, goes directly to the other CEM/O
2
analyzer to provide the wet reading. Both
sensors should measure the same sample without a time delay that could affect the
accuracy of the reading.