Model 1211H Sensor; Model 1311Dr Sensor - GE Optica Operator's Manual

2.6.3 Model 1211H Sensor

The Model 1211H is a two-stage sensor with 65°C (117°F) of depression capability. It features wetted parts of stainless
steel and may be used at higher temperature and pressure than the D2 sensor. The Model 1211H can be used as a
benchtop sensor, mounted to a heat sink. Features include a field-replaceable mirror, optics and cooler assembly. See
the Chilled Mirror Sensor Comparison Chart in Appendix D. "Chilled Mirror Sensors".

2.6.4 Model 1311DR Sensor

The 1311DR is a stainless steel, liquid cooled, four-stage sensor suitable for measuring dew points between
–75°C and +25°C.
Mount the 1311DR sensor so that the air inlet and exhaust openings are free from obstruction (see Figure 21 below). If
the sensor is liquid cooled, vertical wall mounting is recommended, observing the "UP" arrow on the case. This
ensures that condensation forming on cold portions of the 1311DR will drain from the enclosure.
At room temperatures (25°C) with air cooling, dew points from –65°C to +25°C can be measured. When operating it
without liquid cooling, switch on the built-in fan. For lower frost point measurements, a chilled-water coolant loop can
be used for cooling. Make sure the fan switch is off when using liquid cooling.
Sample flow rates from 0.5 to 5 SCFH (0.25 to 2.5 L/min) should be used.
CAUTION!
Doing so may decrease the life of the thermoelectric heat pump.
Liquid cooling is required for measuring frost points below –65°C (at 25°C ambient), and may be used to create faster
response at higher dew point temperatures. If a recirculating chiller is used, it should have a capacity of at least
300 watts at the coolant temperature. Switch the internal fan ON if air cooling is used; leave it OFF for liquid cooling.
Install the gas sampling lines according to the instructions listed in "Sampling Lines" on page 19.
Optica™ Operator's Manual
If it can be avoided, do not operate the sensor continuously at or near full depression.
Figure 21: Model 1311DR Sensor
Chapter 2. Installation
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