Kahn Optidew Bench Top, User Manual, Page: 41 / 88

Optidew User’s Manual
32 October 2019
OPERATION
example; you are looking to measure the Relative Humidity of a room
which is controlled by an HVAC vent at either end (see figure 25) you will
get very different readings depending on whether the sensor is positioned
at point A, point B or point C. Point C provides the most representative
sampling point given that it won’t be disturbed by the vent or the door.
A
B
C
1
2
3
4
1. Door
2. HVAC Duct, air into room
3, 4. Ceiling Vents
Figure 25
Room measurement example
2. Gas speed – if you are planning on installing the sensor in a duct,
consider how fast the sample gas is moving through it. Excessive flow
speed will cause displacement of the condensate layer on the mirror,
leading to unstable measurement.
If this is the case, then a guard equipped over the sensor can mitigate
the effects of excessive gas speed by dissipating the sample throughout
it’s surface area. An appropriate guard can be purchased from Kahn
Instruments, or your local representative.