Page 181 - Reciprocating Compressors Operation Maintenance

Operation and Maintenance of Reciprocating Compressors 1 67

Testing reconditioned valves with air pressure is preferred even though
a special fixture will be required. Figure 3-26 shows a test fixture that
can be made relatively simply.
Air pressure of 90-100 psi is applied, and the leak is determined. All
valves will leak somewhat over time, but a properly reconditioned valve
will leak down the pressure relatively slowly. Again, a one-minute test
may be appropriate.

VALVE AIR TESTING B»Q

PRESSURE
HEG.OR FLOW METER
THROTTLE
VALVE D
AIR -X —
SUPPLY
ao-ioo -*—
PSIQ
FIGURE 3-26. Simple fixture for air testing of compressor valves.

Figure 3-27 shows another test stand, available from France Compres-
sor Products.

COMPRESSOR PISTON ROD PACKING

Piston rod packing is almost always the "full floating" type. It consists
of several annular cups, segmental rings, and a flange-like gland held in
the cylinder head stuffing box as a complete assembly by properly pro-
portioned studs and nuts that secure it against a sealing gasket.
The segmental packing (sealing rings) is contained in the cups and is
held together as an assembly by garter springs that hold the rings firmly
on the piston rod. These rings are free to "float" in the cups.
This packing is essentially a precision mechanical seal with ground or
lapped surfaces. Although of rugged construction, it must be carefully
handled and examined to see that it is clean and free of nicks, burrs, and