Chapter 4 - Theory Of Operation; Overview; Divided Flow - GE HumiLab Operator's Manual

Chapter 4 — Theory of Operation

Overview

Divided flow
-40°C DP
Air supply
(optional)
30
Page
The Humilab Relative Humidity Generator uses a divided flow
method to accurately generate a selected relative humidity in a
large test chamber. The selected humidity is controlled using a GE
General Eastern Chilled Mirror Hygrometer System. This chapter
describes divided flow and the chilled mirror controller.
The Humilab's chamber RH is controlled by time proportioning a
fraction of an air stream through a saturator and a desiccant. The
saturated air mixes with the dry air to produce the desired RH
value in the chamber. Figure 10 shows the basic block diagram of
the Humilab's operation.
temperature coil
(surrounding chamber)
Water jacket
Desiccant
Cartridge
Pump
Solenoid
valve
The operator selects the desired relative humidity on the front
panel, using the increment/decrement switch to scroll to the value.
The selected RH determines the duty cycle of a solenoid operated
wet air/dry air valve.
Dry gas
Wet Dry
gas gas
in in
Test
chamber
Sparger
(bubbles air
through water)
Figure 10 — Basic Block Diagram
Chapter 4 — Theory of Operation