Finish Thompson BE-15/15C - Manual (Page 29)

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PROBLEM: PRESSURE RELIEF VALVE KEEPS DISCHARGING.
Possible Cause 1: Stuck/faulty Divert Solenoid Valve.
Determine whether the Divert Valve is stuck between two positions. During normal operation, the Distillate
Piping is open and at atmospheric pressure during the water process. Once the glycol process begins, the
Divert Valve switches positions to allow the Distillate Piping and the Process Tank to be under up to -28” Hg.
of vacuum.
 If the unit “belches” while filling the Process Tank or reads a partial vacuum during the water process, the
Divert Solenoid Valve is stuck between two positions. A stuck Divert Valve allows pressure to build up
in the Process Tank, which blows the Pressure Relief Valve.
Refer to the “Service Procedures: Divert Valve Repair or Replacement” section of this manual for further
instruction on servicing the Divert Valve.
Possible Cause 2: Debris in, weak, or improper Pressure Relief Valve.
If foreign matter or debris accumulates inside the seat area of the Pressure Relief Valve the valve may
become too sensitive. Further, after time, continuous exposure to vapors from exceptionally acidic Waste
Coolant vapors can degrade and corrode metal parts in the valve, thereby weakening it. Remove and inspect
the Pressure Relief Valve and look for any signs of debris or corrosion. Attempt to clean the internals of the
valve and reinstall. If there are signs of corrosion or damage, replace the valve.
Always replace the Pressure Relief Valve with one rated with identical specifications. A “water heater” type
is not acceptable—their temperature rating is too low for the operation of a BE unit. The valve must be rated
for 30 psi and a temperature of at least 425°F. If in doubt, use a Pressure Relief Valve supplied by FTI.
Possible Cause 3: Clog in Distillate Piping.
The Pressure Relief Valve is installed to protect the Process Chamber and Distillate Piping from over-
pressure in the event of blockage within the piping.
The more likely areas for debris buildup and blockage are in the Distillate Piping before the Divert Valve or
the Condenser. An accumulation of debris can also occur where the Distillate Piping attaches to the Process
Tank.
 Attempt to back-flush the blockage out through the Process Tank’s drain.
1. Drain the Process Tank of all liquids.
2. Place a drain pan under the Drain Valve and open the Drain Valve.
3. Attach a water source to the Processed Water Hose (e.g., a garden hose with a nozzle).
4. Turn on the water supply and allow the water to drain into your drain pan.
 If the flushing water seems to be restricted, a teardown and cleaning of the Distillate Piping may be
necessary. Start with the Divert Valve and work your way back to the Process Tank, cleaning out each
component as they are removed. Also clean out the opening in the Process Tank. Reassemble the piping
and components using PTFE plumber’s tape to ensure tight, leak-free connections.