Supplemental Manual
High-
IsoDry™ RH Control System
©
Copyright 2017 Terra Universal Inc. All rights reserved • Revised November 2020 • Document No. 1788-26
Terra Universal, Inc. • TerraUniversal.com • 800 S. Raymond Ave. • Fullerton, CA 92831 • TEL: (714) 578-6000 • FAX: (714) 578-6020
8
Internal Pressure: Press and hold DOWN
(displays internal cabinet pressure in milli-inches of WG)
On systems with very large plastic access doors, a continuous purge can cause temporary door deflection
and gas leakage. This condition does not indicate a permanent leak and generally does not damage the
cabinet. When pressure is removed, doors return to their natural position and re-establish an effective seal.
This deflection does, however, result in nitrogen waste and indicates the need to reduce the flowmeter
setting.
NOTE
Purge Timer: Press and hold UP and DOWN
simultaneously to review the number of seconds the high-flow
purge is active after set-point is reached. To change this value, see "Initial Programming" above.
"Hi" Indicator
indicates that the Dual Purge System is in high-purge mode (you will see at least one bar to the
right of this display, which indicates an internal positive pressure).
Flashing "Lo Pres"
indicates the absence of incoming line pressure. Check the line for proper connection, and
check the nitrogen source to ensure to ensure incoming flow.
4.
Flowmeter Operation
: The Dual Purge System includes a flowmeter, which provides a continuous low-level
purge to maintain a constant positive pressure inside the cabinet. The flowmeter also ensures uninterrupted
nitrogen flow if power or system electronics ever fail.
If continuous purging is desired, open the flowmeter to 5 – 10 SCFH (depending on chamber size). This is
recommended if you require a very low humidity set point (less than 10%RH) or if doors are frequently opened.
Continuous purging will tend to drive the %RH level very low.
If continuous purging is not required, close the flowmeter. The Dual Purge System will initiate a gas purge only
when the humidity level climbs above the set point.
5.
Dilution Fan Adjustment:
The dilution fan speed control, located on the rear of the Dual Purge panel, allows
fan speed adjustment. Turn the knob clockwise to speed up the fan (maximizing dilution efficiency), or counter-
clockwise to slow down the fan (reducing turbulence inside the cabinet).
NitroWatch™ Operation
1.
Initial Programming:
Turn ON the Dual Purge System while holding down the SET button on the NitroWatch
control panel (the left button on the front control panel).
Each time you release and then press and hold the SET button, you will advance through the following control
functions. Use the UP/DOWN buttons to change default settings (shown in parentheses):
Door
Number of seconds to delay after the door is opened before turning on the beeper alarm.
rH
Relative Humidity High Purge Delay Alarm: No. of seconds the RH level must remain above the set
point to activate the alarm (default: 60)
beeP
Enables/Disables Beeper Alarm (default: ON)
hU
HUMEX operation selector – when in the OFF mode, the system operates as a NitroWatch
(maintaining below-ambient humidity). In the ON mode, the system operates with Terra's Humex2
(maintaining above-ambient humidity). Default: OFF.
