Preventive Maintenance Flashcards

In an ammonia system, where does lubricating oil tend to collect, requiring periodic draining?

Answer: In low points of the low side, such as oil pots and vessel bottoms

Oil is heavier than and largely immiscible with liquid ammonia, so it settles at low points.

Under ANSI/IIAR guidance, how often should pressure relief valves on ammonia systems typically be replaced?

Answer: Every 5 years

IIAR recommends replacing relief valves every five years because internal corrosion and debris can prevent proper operation.

Condenser pressure is consistently higher than the saturation pressure corresponding to the liquid leaving the condenser. What is the likely cause?

Answer: Non-condensable gases in the system

Non-condensables such as air add partial pressure, raising head pressure above saturation pressure.

What is the main purpose of a water treatment program for an evaporative condenser?

Answer: To control scale, corrosion, and biological growth such as Legionella

Water treatment prevents scaling, corrosion, and microbial growth that hurt performance and safety.

Before opening a section of ammonia piping for maintenance, which step is required first?

Answer: Isolate, pump down, and lock out/tag out the section

Isolating, evacuating, and applying lockout/tagout protects workers from releases of energy and ammonia.

When inspecting a unit cooler after defrost, an operator finds ice building up in the drain pan. What should be checked first?

Answer: The drain pan heater and the drain line for blockage

Ice in the drain pan usually means the drain is blocked or the pan heater has failed.

How often should ammonia leak detectors be tested or calibrated?

Answer: At the frequency specified by the manufacturer and applicable code, at least annually

Detectors drift over time and must be tested on a set schedule, at least annually under IIAR 6, to remain reliable.