Excessively low air pressure occurring in the intercooler of a reciprocating air compressor is caused by __________.

Correct Answer: Option D — leaky discharge valves on the LP cylinder

If the low-pressure (LP) cylinder discharge valves leak, high-pressure air from the intercooler backflows into the LP cylinder during the compression stroke. This leakage prevents the intercooler from maintaining its design pressure, as the air is effectively recirculated rather than being compressed and passed to the next stage.