USER MANUAL
Series HC
Reference No. 145 Final Rev 5
Page 44
September 2004
SECTION 6:
(Continued)
6.2.6
Two-way Valve Leakage
Valve leakage here will allow relatively wet inlet air to leak into the dry outlet air
stream, thereby raising the dewpoint of the composite air. Compare the
dewpoint of the air at the dryer outlet to the dewpoint measured at the top
(outlet) of the drying tower (i.e., at the relief valve location). If there is a
significant difference in dewpoint, one or both closed 2-way valves is leaking.
Check actuator operation and check for seat wear.
6.3
FAIL-TO-SHIFT
6.3.1
Solenoid Valve Failed To Operate
Check electrical connection, coil, and valve seat.
6.3.2
Pilot Air Tubing Leakage
Check tubing fittings for leakage.
6.3.3
Two-way Switching Valve Actuator Leakage
A leaking actuator can cause the switching valve to malfunction; low pilot
pressure due to leakage (or solenoid valve failure) will cause the FAIL-TO-
SHIFT ALARM to activate. Check for leakage.
6.4
PRIMARY DRAIN FAILURE
6.4.1
Plugging Or Sticking Due To Foreign Matter
If the PRIMARY DRAIN FAILURE ALARM activates, the probable cause is
sediment plugging the orifice or impeding the proper operation of the float.
Disassemble, inspect, and clean as necessary.
