Page 128 - Reciprocating Compressors Operation Maintenance

Operation and Maintenance of Reciprocating Compressors 115

DISCHARGE /SIGHT WELL
CHECK VALVE

SUPPLY K M ft (7 IW ADJUSTMENT
INLET KWrtl 0 I BJL^-^SCREW
SHUTOFF
BALL ^-^11 HJB RESERVOIR
L

ROCKER ARM
ASSEMBLY

SUCTION
TUBE

CAM- _
STRAINER

Pumps With Sight Glass

FIGURE 3-3. Force-feed box lubricator with sight glass (Source: Lubriquip,
Inc., Cleveland, Ohio).

the valve closes. The supply inlet shutoff ball is then unseated and lubri-
cant is drawn into the piston cylinder from the sight well. This creates a
pressure reduction (vacuum) in the air-tight sight well that causes lubri-
cant from the reservoir to be drawn into the well until pressure is equal-
ized. On the piston upstroke, the oil in the cylinder is injected through
the discharge check valve to the machine injection point. The number of
drops seen falling in the sight well is the amount of oil discharged by the
pump. Each pump can be adjusted by means of an external screw. This
changes the length of the pump stroke, which changes the pump dis-
charge volume.