An orifice test shows whether an air compressor, shown in figure 2.6, can maintain a specified
reservoir pressure while air is escaping through an orifice; pressure varies with the dimensions of the
orifice and the speed of the compressor. A condemning limit is usually set at approximately 80 percent
of the capacity of a new compressor. The compressor should be reconditioned if air escapes from the
orifice faster than it can be pumped.
Figure 2.6. Air Compressor.
Repairs to the air compressor consist principally of thorough cleaning, installing new piston
rings, and renewing valves. The bearings of the air compressor crankshaft should be inspected and
replaced if necessary; unless bearing trouble is experienced, the crankshaft will require little attention for