Page 121 - Reciprocating Compressors Operation Maintenance

108 Reciprocating Compressors: Operation and Maintenance

• Increased reliability
• Reduced cost of system downtime, spare parts, new oil, and labor for
repair
• Minimum power consumption

A lubricant is expected to:

• Separate rubbing parts
• Dissipate frictional heat through cooling and heat transfer
« Flush away entering dirt as well as debris
• Minimize wear
• Reduce friction loss and power required
• Reduce gas leakage
• Protect parts from corrosion
• Minimize deposits

In the lubrication of reciprocating compressors, two somewhat differ-
ent groups of requirements must be considered: first, those of the bear-
ings of the driving end, and second, those of the compressor cylinders.
In both bearings and cylinders the lubricating oil must form and main-
tain strong films that will minimize friction and wear. In cylinders, it
must render this service with the rate of oil feed kept at a minimum and,
in addition, it must protect against rusting and aid in sealing the piston,
valves, and rod packing against leakage. However, bearings are supplied
with large quantities of oil; this oil is used over and over for long periods.

CRANKCASE OR BEARING LUBRICATION

In practically all reciprocating compressors, the oil charge for lubrica-
tion of bearings is contained in a reservoir in the base of the crankcase.
Oil from the bearings, crossheads, or any cylinder open to the crankcase
drains back to the reservoir by gravity. However, a variety of methods
and combinations of methods are employed for delivering oil from the
reservoir to the lubricated parts.

Splash Lubrication

Oil may be delivered to lubricated parts entirely by splash. In these
compressors, a portion of, or projection from, one or more cranks or con-