When should a stem-type service valve be front-seated?

A) during normal operation
B) when taking gauge readings
C) whenever the compressor has to be isolated
D) all of the above

Stem-Type

Referring to a type of valve or control that uses a stem-like component to operate or regulate flow.

Service Valve

A valve used in various mechanical and fluid systems for maintenance, repair, or diagnostic purposes, allowing for control of fluid flow.

Front-Seated

Typically refers to valves in refrigeration or HVAC systems that are in the open position when the valve stem is screwed in all the way.