CB9A-020 page 4
GENERAL INFORMATION
MAXIMIZING COMPRESSOR LIFE
Life of critical compressor components such as piston rings, valves and packing will vary considerably with each
application, installation, and operating procedures. Premature failure of wear parts can often be attributed to
one the following causes:
1. Excessive Temperatures
Primary causes are:
Operating at pressures other than those originally specified.
Handling a different gas than originally specified.
Clogged strainer or filter elements.
Line sizes too small, or other flow restrictions.
Excessive ambient temperature or suction gas temperature.
Cooling water temperature too high, or coolant flow too low.
Valve problems (see Foreign Material below).
Badly worn piston rings (see Foreign Material below).
Lower operating temperatures will significantly increase valve and piston ring life.
2. Foreign Material
Solid particles in the gas stream will:
Rapidly wear the piston rings and score the cylinder wall.
Destroy the rod packing causing excessive leakage and score the piston rods.
Lodge in the valves causing loss of capacity and broken valve plates and springs.
Liquid in the gas stream will:
Cause broken valve plates and springs.
Destroy the compressor if present in sufficient quantity.
On new installations, it is suggested that the valves and piston rings be inspected after the first few hundred
hours of operation. This will give an early indication of any abnormal problems and allow for corrective action to
be taken before a costly failure results. Although piston ring life will vary from application to application, wear
will be fairly consistent on subsequent sets of rings.
SUCTION VALVE UNLOADERS
Compressors may be fitted with suction valve unloaders to provide loadless start or capacity control functions.
Blackmer unloaders are basically a piston and a plunger atop the suction valve. When pressure is applied to
the top of the unloader piston, it and the plunger move downward, pushing the suction valve off its seat and
unloading the compressor. When the pressure signal is removed, the unloader spring pushes the piston and
plunger back up and the suction valve will resume normal operation.
In order for the unloaders to function, the unloader pressure must be at least 30 psi (207 kpa) above suction
pressure.
SEAL (PACKING) ARRANGEMENTS
Single, Double and Triple Seal models are available to provide
a wide range of leakage control/containment options. Before
starting work on the compressor, note the seal orientation
indicated by the 6th digit of the Compressor ID # shown on the
compressor's nameplate. Also note any tubing connections in
the seal area. 1/4" NPT ports are provided between each pair
of seals to allow proper venting or pressurization of the seal
areas (double and triple seal models only).
SEAL ORIENTATION -
SINGLE SEAL COMPRESSORS
