BLACKMER HD942A, Installation, Operation And Maintenance Instructions

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COMPRESSOR ASSEMBLY
CB9A-030 page 17/28
7. CYLINDER ASSEMBLY
a. The cylinder should be installed with the valves
removed.
b. Set the cylinder on the crosshead guide over
the piston rods and packing boxes.
c. Ensure that the valve cutouts on the upper
packing boxes are aligned with the cylinder
valve pockets.
d. Place the pistons (without shims or rings) on
the rods. Rotate the compressor by hand and
verify that the pistons are centered in the
cylinder bores. The pistons must not touch the
cylinder walls. Adjust the cylinder as
necessary.
e. Install the cylinder capscrews and tighten
evenly per Table 7 - "Bolt Torque."
f. Remove the pistons.
8. Rotate the flywheel by hand to ensure the
compressor turns freely.
Figure 10 - Cylinder and Piston
9. PISTON INSTALLATION
a. To set the piston clearance, remove the valves
from one side of the cylinder.
b. Rotate the flywheel by hand to bring one piston
rod to top dead center.
c. Set the bottom shim washer(s) onto the piston
rod.
d. Place the piston (without rings and expanders)
on the piston rod.
e. Place the upper shim washer(s) over the rod
onto the piston.
f. Install the piston cap (without the O-ring).
g. Tighten the piston nut on securely.
h. Install the head (without the O-ring), and tighten
the head bolts securely.
i. Ensure that the piston is at top dead center.
Measure the clearance between the piston and
head through one of the upper valve pockets.
j. Rotate the crankshaft until the piston is at
bottom dead center. Measure the clearance
between the piston and packing box through a
lower valve pockets.
k. Compare the piston clearance values to those
in Table 10 - "Piston Clearance."
Upper Piston
Clearance
0.035" - 0.050"
(0.89 to 1.27 mm)
Lower Piston
Clearance
0.003" - 0.005"
(0.08 to 0.13 mm)
Table 10 - Piston Clearance
l. Remove the piston. Repeat steps b - k with
revised shimming until both clearances values
are satisfactory.
m. Once the proper shims are determined, remove
the piston again.
n. Install an expander and piston ring in each
groove in the piston. The gap in each
expander should be 180° from the gap in the
piston ring. In addition, each piston ring's gap
should be 180° from that of adjacent ring(s).
o. Squeeze the piston rings inward with light
pressure and work the piston into the cylinder
over the rod.
p. Place the upper shim washer(s) over the rod
onto the piston.
q. Install the piston cap and O-ring.
r. Tighten the piston nut per Table 7 - "Bolt
Torque."
s. Install the head with its O-ring, and evenly
tighten the head bolts per Table 7 - "Bolt
Torque."
t. Repeat same procedure for the second piston.
u. Verify the proper upper and lower piston
clearance before proceeding.
10. Install the valves per "Valve Replacement" Section.
11. Rotate the compressor by hand to verify that it turns
freely.
12. Refer to the "Pre-Startup Check List", and "Startup
Procedure."
13. After the compressor has run for a sufficient time to
reach operating temperature, allow to cool and
retighten the valve hold down screws.