Jenny Reciprocating Air Compressors, Operation And Maintenance Manual

Page: 16 / 53

16
or gasoline engine V-belt drive sheave assembly. The pumping unit is either a Single Stage or Two
Stage Reciprocating Pump.
SINGLE STAGE AND TWO STAGE RECIPROCATING PUMPS
Reciprocating (Piston) Compressors can be widely found in these two primary conf gurations; Single
Stage and Two Stage.
Single stage air compressors work by drawing free air in and subsequently compressing the air to its
f nal pressure in a single piston stroke. Single stage air compressors can attain pressures of up to 150
PSI. Typically, a single stage pump will have a higher CFM(Cubic Feet per Minute) rating than a two
stage pump because every cylinder is drawing in air and compressing it with air during every rotation.
Two stage air compressors work in a very similar manner with the primary difference being that they
compress the air in 2 steps or stages. During the f rst step or stage, air is drawn in and compressed to
an intermediate pressure. After being compressed in the f rst stage, the air is piped, usually through
an intercooler where the air is allowed to cool, to be compressed in the f nal or second stage. Two
stage compressors are normally good for pressures up to 200psi. Two stage pumps are more eff cient
at higher pressures because the air is cooled between the stages.
ELECTRIC MOTOR
A single or three phase, open drip proof, electric motor, is furnished to drive the air compressor
assembly. Depending on the horsepower rating of the motor and phase, the motor is capable of
operating on different voltages(please see following chart) by changing the wiring in the motor and
starter(if greater than 5HP). These changes should only be attempted by a qualif ed electrician.
Motor HP Rating Voltage Phase
1/3 thru 2 HP 115V, 208V or 230V Single Switchable
3 thru 7-1/2 HP 208V or 230V Single Only
1/3 thru 25 HP 208V Three Only
1/3 thru 25 HP 230V or 460V Three Motor and Starter Switchable-Different Motor Overloads
1/3 thru 25 HP 575V Three Only
GASOLINE ENGINE
A Honda OHV gasoline engine can be furnished to drive the air compressor assembly. The
engines are all industrial/commercial grade and can be either 5.5, 6.5, 8, 11, 13, or 18 HP depending
on the requirements of the air compressor pump.
AIR CONTROL SYSTEM
Constant Run Units - Head Unloader and Discharge Unloader
The air intake is regulated by discharge air pressure demand. A pilot valve is used to operate
an unloading device in the compressor head or a line discharge unloader. For most units, air pressure
is fed through the pilot valve to a specially designed compressor head. The air pressure actuates the
special head’s unloading pins that hold the air intake valves in the closed position. For line discharge
unloaders, a specially designed valve controls the f ow of air. Based on the system pressure, the