Great Lakes Air Products GPS-500 Instruction Manual - Page 10

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TROUBLESHOOTING GUIDE - QUICK REFRENCE

Please read the entire troubleshooting section of the manual before proceeding with

any repairs or modifications. Several topics are addressed at several points in the

manual and understanding them all before you proceed will give you a much better

understanding of the entire process.

Because almost all problems with regenerative dryers will result in a bad Dewpoint it is assumed that

the condition of bad Dewpoint applies to this entire table.

PROBLEM

No / Bad

Regeneration

Cycle / Sequence

Failure

Excessive Inlet

conditions

;

TROUBLESHOOTING TUTORIAL

Filtration & Drains

Identify the pre-filtration for the unit. It should be a high quality coalescing filter. Check that the drain

system is working properly and is not hard piped into other system drains. Hard piped drain systems

will inevitably pump liquid from one point of the system to the other because of operating differential

pressures. Check valves are utilized to overcome this problem in many facilities, but are prone to

failure from the usual debris in drain lines. If a system has a common piped drain system, water

downstream of the filters and dryer is almost impossible to identify.

Regenerative dryers are designed to remove vapor not liquid. Adequate filtration must be employed to

remove all liquid before entering the dryer.

If the dryer pre-filter has a differential pressure gauge, check to see that it reads at least 1 PSID. No

visible pressure drop is usually an indication of a ruptured filter element. If the coalescing filter is

showing large amounts of liquid being drained, it might be overloaded and bypassing liquid. Verify

upstream drains are functioning properly.

Purge Exhaust System

When the system is purging, check the tower pressure gauge on the purging tank. It should be at 0

PSIG (2 PSIG maximum). Any backpressure in the regeneration purge system will impede purge flow

and hinder the regeneration of the desiccant. If the system has mufflers, change the elements. This

should be done annually. If the system has the purge exhaust piped away, locate the cause for the

restriction and eliminate it. It is possible that a bad check valve or inlet valve is allowing process air

into the regeneration system, and this will overload the muffler or piping system. The next section

helps you identify a valve problem.

POSSIBLE CAUSE

No / Low purge stream

Regeneration back pressure

Contaminated desiccant

Low feed voltage

Process, Check, or

Solenoid Valve failure

Timing card failure

Dewpoint Demand Only

Dewpoint meter not

signaling

Liquid at dryer inlet

High inlet temperature

High flow at dryer inlet

Low pressure at dryer inlet

GPS Heatless Regenerative

Page 10 of 14

Proceed to

See Purge Rate Maintenance

See Purge Exhaust System

See Desiccant Testing/Replacement

See

ELECTRICAL CONNECTION

See

OPERATION

See Valve Integrity

See Intermittent Cycle Problems

See

SEQUENCE CONTROLLER

See Dewpoint Demand Controller

See Filtration & Drains

See Ambient & Air Inlet

Page