(i) Follow the prime mover manufacturer's instructions for the method of
protection during extended shutdown.
6 OPERATIONAL PREVENTIVE MAINTENANCE. Operational preventive maintenance
includes the following tasks.
(a) Keep daily operating logs that record pressures and temperatures of
air and water in the compressor, intercoolers and aftercoolers, and of
compressor lubricating oil.Deviations from normal values indicate the
corrective action that must be taken to return the system to normal and to
prevent damage to the equipment from insufficient lubrication or inadequate
(b) The operating log also helps in detecting valve troubles. On
two-stage compressors, low intercooler pressure indicates malfunctioning of
the low-pressure cylinder valves, and high intercooler pressure may be due to
improper operation of the high-pressure cylinder valves. Locate defective
valve by feeling the valve cover plates and determining which is the hottest.
Leaking high-pressure suction valves cause the intercooler pressure to
fluctuate above normal values. Leaking high-pressure discharge valves cause
the intercooler pressure to build up steadily until the safety valve releases
it. Low-pressure discharge valves that leak cause intercooler pressure to
fluctuate below normal intercooler pressure.
(c) Keep compressor clean at all times. Wipe the machine daily with a
cloth. Dirt on the machine will eventually work its way into the lubricating
system. On air-cooled compressors, dirt accumulations form an insulating
blanket causing increased temperatures within the machine and excessive wear
on moving parts.
(d) Clean intake air filter regularly to prevent atmospheric dust from
entering the compressor cylinders.
(e) Keep piston rod packing tight enough to prevent air leakage, but do
not overtighten. Overtightening causes excessive packing wear and scoring of
the piston rod.
7 PREVENTIVE MAINTENANCE INSPECTION. The following inspection schedules are
adequate for average installations.
7.1 Daily Inspection. Inspect the compressor daily for the following
(a) Unusual noise or vibration
(b) Abnormal pressures or temperatures of compressed air, cooling water,
and lubricating oil
(c) Proper unloader operation
(d) Abnormal stuffing box temperatures
(e) Abnormal bearing temperatures