Preventive Maintenance Flashcards

What is the most reliable reference for the correct running oil level in a reciprocating compressor sight glass?

Answer: The compressor manufacturer's specifications

Correct oil level varies by machine design, so the manufacturer's specification is the authoritative reference.

A V-belt drive is being checked during routine maintenance. What is the common rule of thumb for proper belt deflection?

Answer: 1/64 inch per inch of span

A deflection of about 1/64 inch per inch of span is the widely used guideline for V-belt tension.

An operator feels a noticeable temperature drop across a liquid line filter-drier. What does this most likely indicate?

Answer: The drier is restricted and causing a pressure drop

A temperature drop across a drier indicates a pressure drop and flashing caused by a restriction.

In a halocarbon system, a moisture-indicating sight glass shows yellow instead of green. What should the operator conclude?

Answer: Moisture is present and the drier may need changing

On most indicators, yellow (or pink) means wet while green (or blue) means dry.

Why is vibration data on compressors and pumps trended over time rather than checked only once?

Answer: To detect gradual changes that signal developing bearing, alignment, or balance problems

Trending reveals changes from a baseline, allowing repairs before a failure occurs.

A routine oil acid test on a halocarbon compressor comes back positive. What does this most likely indicate?

Answer: Moisture contamination or a motor burnout has produced acids

Acid in the oil typically results from moisture or a motor burnout and requires corrective cleanup.

Which symptom most directly results from a fouled or dirty condenser surface?

Answer: Higher head pressure

Fouling reduces heat rejection, raising condensing pressure and compressor work.