TestEquity 123H, Operation And Service Manual

Page: 31 / 77

Chapter 4 – F4 Temperature/Humidity Controller
TestEquity 123H Temperature/Humidity Chamber Page 4-11
Purge Operation
The Purge mode is enabled through Event 3 (Digital Output 3) in the F4 Controller.
NOTE: The Modbus register to program Digital Output 3 in static set point mode is 2020.
NOTE: In the Profile Create and Edit menus, Digital Output 3 is named
PURGE
. Remember to
set
PURGE
to
On
in all programmed steps when the you want to use the purge.
The Event Outputs are accessed from the
DigitalOut
prompt on the Main Page in static set point
mode, and the
DIGIT OUT
prompt in the Profile programming mode.
For low humidity control
•
Turn Event 2 (
HUMIDITY)
ON and Event 3 (
PURGE)
ON.
•
Purge gas will feed when the F4 Controller cycles the dehumidification system. It will cycle
on/off as the workspace humidity approaches and reaches the low humidity set point, or
whenever dehumidification is necessary.
For low humidity control below +10
°
C
•
Turn Event 2 (
HUMIDITY)
OFF and Event 3 (
PURGE)
ON.
Event 2 (
HUMIDITY)
must be OFF to achieve temperatures below +10
°
C. If Event 3 is ON, the
Purge System will continue to provide controlled dehumidification even though the humidity
system is disabled.
Adjusting the Purge Flow
A flowmeter is located on the front panel to adjust the flow of purge gas into the chamber. The
flowmeter has a scale, calibrated in SCFM. The flow of purge gas should be adjusted to the
minimum amount required to obtain the desired drying in the chamber for your particular
conditions. A suggested starting setting is 2 SCFM.
Relief Vent
Excess pressure in the chamber workspace is vented through a pressure-relief check-valve,
which is located on the top of the chamber.