Flow Rate; Sensor Installation; Model 1111H Sensor - GE OptiSonde User Manual

October 2007

Flow Rate

Sensor Installation

Model 1111H Sensor

2-14
It is important to have adequate flow through the sensor. Too little
flow can slow the response (particularly at very low frost points). Too
much flow can cause instability of the control system at high dew
points and can reduce the depression capability of the thermoelectric
cooler at very low dew points. Too much flow also accelerates the
rate of system contamination. A flow rate of 2 to 2.5 ft
min) is ideal for most applications.
This section provides installation details for the GE Sensing line of
chilled-mirror humidity sensors.
The Model 1111H is an open-type sensor (see Figure 2-12 below)
with 45°C depression capability at 25°C @ 1 ATM. It can be threaded
into standard pipe fittings or mounted in a type 0111D pressure boss,
which encloses it and adapts it for ¼-inch compression fittings. When
installing the sensor in the pressure boss, remove the black aluminum
sensor cover. A second version, the 1111H-GE, extends 9 in. and
includes a duct-mounted flange and a removable PTFE filter.
For maximum thermal conductivity, the base of the Model 0111D
pressure boss should be coated with heat-conducting grease. When so
installed on a surface suitable for dissipating heat, the sensor will
achieve its maximum rated depression. See the Chilled Mirror Sensor
Comparison Chart in Appendix D.
Figure 2-12: Model 1111H Sensor for Duct Mounting
3
/h (∼ 1 liter/
Installation