GE Optica, Operator'S Manual

Page: 41 / 150

January 2006
2-20 Installation
Purging the Sensor
Caution!
The 1311XR must be purged after each use, either with
the sample gas after measuring it, or with another dry
gas source. Otherwise, condensation inside the sensor
housing may cause corrosion and eventual failure of the
thermoelectric coolers.
For extremely dry gas measurements, the 1311XR sensor enclosure
must be purged with a gas having a frost point lower than –20°C. For
intermediate temperatures, any gas having a frost point at least as low
as the sample gas can be used.
The sample gas outflow from the sensor can be used for this purpose,
if it is suitable (non-explosive, non-lethal, etc). Introduce the purge
gas to the enclosure via the purge fitting on the rear of the sensor. The
simplest method for purging is to run the sample gas outflow through
the U-tube supplied with the sensor.
Model SIM-12H Heated
Sensor and Components
The SIM-12H heated sensor module is suitable for measuring dew/
frost points between –10°C and +85°C. It contains precision heating,
as well as cooling, capability. Three separate heaters are located in the
sensor walls, 120 degrees apart. Three temperature sensors measure
the body temperature at those points, and three control circuits
precisely adjust the temperature of each heater. Any detected
temperature gradient across the sensor cavity is immediately
eliminated, resulting in very even control. All three heaters are
controlled by the temperature set by the front panel selector knob.
The sensor is a two-stage unit, providing 65°C of depression
capability, and 60°C actual measurement range.
Type SIM-HFT Heated
Filter Module
The SIM-HFT heated filter module allows the sample gas to be
purged of particulate contaminants prior to entering the sensor.
The incoming gas is first passed through a 90-micron prefilter, then a
15-micron final filter. All parts in contact with the sample are heated
to a constant 105°C, eliminating any possibility of condensation. The
sintered filters are easily removed for cleaning or replacing if
required.
Type SIM-HFM Heated
Flow Meter
The SIM-HFM heated flow meter module allows the sample gas flow
rate to be both measured and controlled at a rate that is optimum for
the sensor. A metering valve mounted on the front panel allows
control over a range of 0 to 2 ft3/h. All parts in contact with the
sample gas are heated to a constant 105°C, so that no condensation
occurs. The flow meter is normally mounted downstream from the
heated sensor.