Troubleshooting - Quincy QP Series Instruction Manual

2 stage compressors

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Table Of Contents

Table of Contents

SECTION 6

Trouble

Low discharge pressure

Water in the crankcase

(lubricant appears milky)

Rusty valves

and/or cylin ders

Excessive vibration

QP Series

2022201802, July 2014

Probable Cause

•Restricted inlet

•Defective compressor valves or valve unloading mechanism

•Leaks in the compressed air distribution system at fittings, connections,

etc.

•Unloader pilot valve defective or set wrong

•Pressure switch defective or set wrong

•Drive belt slipping

•Incorrect speed

•Worn piston rings or loose piston

•Leaking head gasket

•Drain valve open

•Defective pressure gauge

•Pressure relief valve leaking

•Clogged intercooler

•Compressor incorrectly sized for the altitude it is operating at

•Piston rings not seated; allow 100 hours at full pressure

•Compressor does not run long enough to get hot and vaporize the liquids

squeezed out of the air during compression (compressor may be too large

for application)

•Incorrect or inferior grade of lubricant

•System pressure leaking back through discharge valve

•Compressor operated too infrequently

•Compressor does not run long enough to get hot and vaporize the liquids

squeezed out of the air during compression (compressor may be too large

for application)

•Compressor not properly prepared for storage

•Discharge line from compressor head is pointed upward allowing con

densation to drain back at shutdown

•Incorrect speed

•Compressor valves not functioning properly

•Loose pulley/sheave

•Compressor, motor or engine not secured tightly, or tightened into a

bind

•Foundation or frame inadequate

•Piping inadequately supported or tightened into a bind

•Excessive discharge pressure

•Compressor feet may need to be leveled with shims