Page 152 - Med Plaza and Cancer Center

"Oil-Less” Medical Air Medical Systems

6.0 Inspection/Replacement Procedures

6.5 Checking/Replacing Piston Ring, Rider Ring and Gaskets (continued)

6. Measure the thickness of the piston and rider rings and compare it to the values shown in Table 6-3.

7. Divide the measured difference from the thickness when the rings are new by the hours in service since
the rings were last replaced (or since startup for new installations). This is the approximate wear rate.

8. Multiply the approximate wear rate by the average hours that are expected until the next maintenance
inspection.

9. Subtract that number from the measured ring dimension. If the resulting number is near or below the
minimum value found in Table 6-3, the rings should be replaced. Otherwise, if they are not damaged, they
may be reinstalled (taking care that they are returned to their original position, on their original piston).
Wrap rider rings so that the oval mark (0) is facing in against the piston.

10. If the rings are below tolerance, or otherwise damaged, they must be replaced with new ones. Install the
piston ring with its diagonally cut mating surfaces facing downward. Wrap the rider rings with inside oval
marking (0) facing in against the piston.

11. Reverse above steps to reassemble the compressor. Replace air valve gasket with a new one.

Note: When reassembling the compressor, the recommended torque for the four hex head bolts and the four
cylinder nuts is 41 ft-lb.

Table 6-3 Piston Ring and Rider Ring Dimensions

LifeLine Modular Units (V-Series) LifeLine Modular Units (G-Series)

Piston Rings Rider Rings Piston Rings Rider Rings
Model Radial Radial Radial Radial Model Radial Radial Radial Radial
Hp Thickness Thickness Thickness Thickness Hp Thickness Thickness Thickness Thickness
(Inches) (in.) (in.) (in.) (Inches) (in.) (in.) (in.)
New Minimum New Minimum New Minimum New Minimum
1 .177 .142 .055 .047 1 .177 .142 .055 .047
2 .256 .193 .079 .063 2 .256 .193 .079 .063
3 .256 .193 .079 .063 3 .256 .193 .079 .063
5 .295 .232 .094 .067 5 .256 .193 .079 .063
7.5 .295 .232 .094 .067 7.5 .256 .193 .079 .063
10 .354 .291 .106 .079 10 .354 .291 .106 .079
15 .354 .291 .106 .079 15 .354 .291 .106 .079
20 .410 .330 .132 .097 20 .410 .330 .132 .097

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