Pneumatech PH Series - PHM Series Troubleshooting

Pub. No. OM-A-10H REV. 7 — June 2006 21
L. Tower does not fully pressurize. 1. Inlet pressure low.
2. Purge pressure too low.
3. Repressurizing period too short.
1. Calibrate and plot purge pressure
and reset.
2. Reset proper purge pressure.
3. Check timer sequence of
operation.
M. Excess desiccant dust.
NOTE: If the regenerating tower does
not fully pressurize, desiccant attrition
takes place at the time of tower switch-
over.
1. See K & L.
2. Excess flow due to greater
demand in process or addition of
extra compressors.
2. Check outlet flow.
Table 1 — Troubleshooting Guide for PH & EH Series Heatless Regenerative Dryers, continued
Symptoms Cause Remedy
Table 2 — Troubleshooting Guide for PHM Mini Series Heatless Regenerative Dryers
Symptoms Cause Remedy
A. Elevated Dewpoint. 1. Low inlet pressure.
2. Excess moisture carryover.
3. Excess gas inlet flow
4. Desiccant coated with oil.
5. Low inlet air temperature.
1. Increase pressure (minimum 75
PSIG), or reduce flow.
2. Check drains at aftercooler and
prefilter.
3. Check the total output of
compressors.
4. Depressurize the dryer and
replace the desiccant.
5. Raise inlet temperature above
75°F.
B. High back pressure on regenerat-
ing tower.
NOTE: The tower should be at ‘0’
PSIG during regeneration cycle. Any
back pressure will result in improper
regeneration.
1. Muffler plugged.
2. Shuttle valve leaking.
1. Replace muffler.
2. Clean, repair or replace valve.
C. Excessive flow through muffler. 1. Shuttle valve sticking.
2. Purge valve sticking.
3. Timer short-circuited.
1. Clean, repair or replace valve.
2. Clean, repair or replace valve.
3. Replace faulty timer.
D. Failure to switch. 1. Inlet valve did not switch.
2. Timer short-circuited.
1. Clean, repair or replace valve.
2. Replace faulty timer.
E. High pressure drop in dryer. 1. Desiccant retainer screen
plugged.
2. High purge flow.
3. Purve valve stays open.
1. Replace desiccant retainer
screens.
2. See C1 to C3.
3. Clean, repair or replace valve.
F. Dryer fails to purge. 1. Orifice plate plugged.
2. Purge valve stuck closed.
1. Clean the orifice plate.
2. Clean, repair or replace valve.