Page 287 - Reciprocating Compressors Operation Maintenance

272 Reciprocating Compressors: Operation and Maintenance

Side Clearance

r End Clearance

Gas or
Fluid
Pressure
FIGURE 4-26, Gas pressure action on piston rings.

Piston Ring Clearances

The suggested minimum side clearances between ring groove (side)
and end (gap) clearances for piston rings of various material are given
below. Caution should be taken to make sure that each ring has the mini-
mum end clearance. Unless there is sufficient clearance, ring ends may
butt together from thermal expansion, causing ring wear, cylinder scor-
ing, and other damage.
The end clearances shown in Table 4-4 are for butt cut or step joint
rings, as shown in Figure 4-27.
For angle cut joints, multiply the value in the table for end clearance
by the amounts shown in Figure 4-28.

TABLE 4-4
END CLEARANCES FOR BUTT CUT OR STEP JOINT RINGS

Side Clearance End or Gap Clearance
Material (Per inch of width) (Per inch of eyl, dia.)
Cast Iron .006" (.002" min.) .002"
Bronze .006" (.002" min.) .003"
Teflon .018" .017"
Carbon .006" (.002" min.) .002"