What does its pressure tell the technician?
Refrigeration · EPA 608 Type II. The correct answer, and the reasoning behind it.
Identifying refrigerants, system components and the state of refrigerant in each.
The question
An idle R-22 system with both liquid and vapor inside has been sitting in a 75 °F room. What does its pressure tell the technician?
- Nothing, because idle pressure is random
- The saturation pressure of R-22 at about 75 °FCorrect answer
- The amount of refrigerant in the system
- The pressure the compressor produced the last time it ran
Why “The saturation pressure of R-22 at about 75 °F” is correct
When liquid and vapor sit together at the same temperature, the pressure equals the refrigerant's saturation pressure at that temperature. Comparing the reading with a pressure-temperature chart can confirm the refrigerant or reveal non-condensables.
Source: EPA: Test Topics
Why the other answers are wrong
- Nothing, because idle pressure is random — Idle pressure follows the pressure-temperature relationship, not chance.
- The amount of refrigerant in the system — Pressure in a saturated system does not show how much refrigerant is present.
- The pressure the compressor produced the last time it ran — Once idle, the pressures equalize to the saturation pressure.
Practice more of this
More EPA 608 Type II practice questions, or see every EPA 608 practice test.
Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.