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DTX10 - DTX80 USER GUIDE
13. Optional DDS
13.1
Quick-Start for Dryers Equipped with DDS
The following steps are all that is normally required for start-up of dryers equipped with the DDS System.
Refer to the remainder of this manual for more detailed information on DDS Operation.
Please read entire Dryer Manual before proceeding.
1.
The unit is prewired to the dryer at the factory with the exception of the probe to cable
connection at this time.
2.
Purge the sample line of any desiccant dust by opening isolation valve. Use caution as
pressurized air and dust will blowout off open port.
3.
Close isolation valve. Install the probe in the 1/2” SAE port provided. Hand tighten the nut,
and then using a wrench tighten the nut another turn and a half.
4.
Slowly open the isolation valve to the full open position. It is imperative that the isolation
valve be fully open so that the DDS reads pressure dew point. The sample line is fitted
with coiled capillary tubing to control the sample air flow. There must be continuous flow to
obtain an accurate reading.
5.
Following exposure of probe to line pressure, allow it to stabilize for 4 hours prior to connecting
the probe cable. Failure to do so may cause premature failure not covered by warranty.
6.
After 4 hours connect the probe to the analyzer via the cable provided.
7.
The probe and dryer system may require 48 hours or more to reach desired dew point on
initial or subsequent start-ups. High humidity alarms should be disregarded until this time.
8.
The unit is normally factory set for -40°F (-40°C) switching and -20°F (-29°C) high
humidity alarm.
9.
Dry contacts rated at 120/250 VAG, 2.5 amps are provided for remote annunciation of high
humidity alarm. A linear 4 to 20mA output corresponding to dew point is also provided.
10.
Both the switching and high humidity relays are fail-safe. In the event of probe or electronics
failure, the dryer will switch to the fixed cycle, the high humidity alarm will activate, and a
diagnostic code will flash on the digital display.
11.
Although the probe can be exposed to brief periods of liquid saturation, it can not be exposed
to continuous wet conditions. Remove probe to dry location if these conditions exist.
It is recommended that the probe be returned to the factory once a year for recalibration to standard
gases in order to maintain accuracy. Contact factory for further information.
13.2
Design and Theory of Operation
The DDS is a microprocessor controlled Pressure Dew Point (PDP) analyzer. The DDS
consists of a gold/aluminum oxide sensor probe and an electronics module. The microprocessor
calculates moisture (PDP) that is compensated for temperature and pressure and controls the switching
and alarm set points.
Total dew point control can be obtained with the switching relay, alarm relays, and an optional linear,
isolated 4 to 20mA output corresponding to the PDP.