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UNIT 21 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
21-1) Why would a service technician need a system’s temperature and pressure?
21-2) What does a temperature meter measure?
21-3) What liquids can be used in a glass stem thermometer?
21-4) What is an advantage of the glass stem thermometer?
21-5) What is the pointer of a dial thermometer attached to that causes it to move?
21-6) Why are digital thermometers popular?
21-7) What temperature scales can a digital meter display?
21-8) What are the two thermocouple temperature sensor types commonly used in
HVACR work?
21-9) What are some advantages of thermocouples?
21-10) Why must the thermocouple tip be tightly pressed against the line?
21-11) How does an infrared thermometers measure temperature?
21-12) What color surface temperature can be read most accurately with an infrared
thermometer?
21-13) What units are used to measure pressure in HVACR systems?
21-14) What is the approximate maximum high side pressure on an R22 gauge?
21-15) What is the approximate maximum high side pressure on a R410A gauge?
21-16) Why is it dangerous to use gauges not specifically designed for R-410A on
a system charged with R-410A?
21-17) What is a refrigerant gauge manifold is used for?
21-18) What are the three positions to set the hand wheels that control the valves on
the end of the manifold?
21-19) What happens when the low side hand wheel is turned open slightly?
21-20) Why would some test instruments sense both the low-side pressure and the
low-side line temperature?
To determine the systems superheat?
21-21) Why would a large refrigerant leak be dangerous?
21-22) How does an electronic leak detector work?
21-23) How does an ultrasonic-type leak detector work?
21-24) What type of dye can be use for a fluorescent dye-leak checker?
21-25) How many microns are in 1 inch of mercury?
21-26) What units can most digital scales display?
21-27) What refrigeration service procedures are digital scales used for?
21-28) Why is the ability to zero a scale with weight on it important?
