Which gauge would a technician read to confirm a small appliance has reached 4 inches of Hg vacuum?
Recovery techniques · EPA 608 Type I. The correct answer, and the reasoning behind it.
Identifying refrigerants, access valves, passive recovery and solderless fittings.
The question
Which gauge would a technician read to confirm a small appliance has reached 4 inches of Hg vacuum?
- The high-side pressure gauge
- The recovery cylinder's scale
- The appliance's thermostat dial
- The low-side compound gaugeCorrect answer
Why “The low-side compound gauge” is correct
A compound gauge reads both pressure above atmosphere and vacuum in inches of mercury below it. Confirming the 4-inch option in 82.156(b)(3) is a vacuum reading, so the compound gauge is used.
Source: EPA: Test Topics; 40 CFR 82.156(b)
Why the other answers are wrong
- The high-side pressure gauge — A high-side gauge usually reads only positive pressure, not inches of vacuum.
- The recovery cylinder's scale — A scale reads weight, not vacuum.
- The appliance's thermostat dial — A thermostat setting has nothing to do with system pressure.
Practice more of this
More EPA 608 Type I 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.