Troubleshooting - Gardner Denver DGH Series Instruction Manual

10. Troubleshooting

SYMPTOM
No power to unit.
10.1 Indicator lights not Off/On switch turned off.
illuminated
Blown fuse.
Off/on switch or board malfunction.
Design conditions exceeded.
10.2 Moisture Indicator Spent desiccant (useful service life has ended).
turns yellow (elevated
Contaminated desiccant (e.g. with oil)
outlet dew point)
Saturated desiccant (saturated with water)
Insufficient purge flow - Purge pressure too low
Incomplete tower depressurization (tower pressure greater
than 2 psig) - Clogged mufflers
Incomplete tower depressurization -
10.3 Premature saturation
Purge/repressurization valve fails to open
of desiccant
Insufficient purge time -
Incorrect controller settings
Insufficient purge time -
Faulty controller
Purge/repressurization valve fails to close (air loss from
mufflers during tower repressurization portion of cycle)
10.4 Tower fails to re-
pressurize to line pressure
Insufficient purge flow -
Purge pressure too low
Excessive purge flow -
Purge pressure too high
10.5 Excessive purge is
Inlet switching valve fails to close.
discharged during purge
cycle
(Models 40 through 450) Shuttle Valve; or (Models 590
through 5400) same tower Outlet Check or opposite tower
Purge Check Valves fail to close.
Fluidization of desiccant bed - design conditions for maximum
rated flow exceeded
10.6 Excessive desiccant
Fluidization of desiccant bed –
dust downstream
Rapid repressurization of offstream tower due to:
Faulty timer
Insufficient purge flow - purge pressure too low
Faulty pressure switches or control board
Offstream tower did not de-pressurize in time and/or below 10
10.7 Switching Failure
psig
Alarm
Offstream tower did not re-pressurize in time and/or above 10
psig
POSSIBLE CAUSE(S) CORRECTIVE ACTION
Check voltage at terminal board.
Turn on.
Replace fuse
Replace board.
Refer to Sections 4 & 8 to determine if dryer is being operated outside of design
limitations.
Replace desiccant.
Take corrective action. Refer to Section 4.1 to determine proper prefiltration before
changing desiccant.
Refer to 10.3 for corrective action. Operation at reduced flow may reactivate
desiccant beds until desired outlet dew point is achieved.
Refer to Section 8 to determine correct Purge Pressure Indicator setting .
Replace muffler inserts
Verify voltage to pilot solenoid valve. Check pilot air pressure (60-120 psig req'd.)
Verify proper actuator operation.
Refer to Section 6 or 7 to determine correct controller cycle settings.
Refer to Section 6 or 7 to verify proper time sequence. Replace controller board as
req'd.
Verify removal of voltage to pilot solenoid valve. Verify proper actuator operation. This
is a spring-assisted, normally closed valve. Check valve for obstruction or seat
damage.
Refer to Section 8 to determine correct Purge Pressure Indicator setting . Purge
Pressure Adjustment Valve should never be completely closed.
Refer to Section 8 to determine correct Purge Pressure Indicator setting .
Verify voltage to pilot solenoid valve. Check pilot air pressure (60-120 psig req'd.)
Verify proper actuator operation. Check valve for obstruction or seat damage.
Repair or replace valve(s) as needed.
Refer to Section 4 or 8 to determine if dryer is being operated outside of design
limitations.
Refer to Section 6 or 7 to verify proper time sequence.
Refer to Section 8 to determine correct Purge Pressure Indicator setting .
Replace components
Check mufflers, check or shuttle valve(s), inlet switching and
purge/repressurization valves, purge pressure adjustment,
and controller settings.
Check air supply to dryer, purge/repressurization valve, purge
pressure adjustment, and controller settings.
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10. Troubleshooting
10. Troubleshooting