70 Unit 8 10. If a vacuum has been pulled on a system and is a leak, the vacuum gauge will A. begin to rise. B. stay where it was when the vacuum pump S. A digital micron gauge A. is used to measure a...

70 Unit 8 10. If a vacuum has been pulled on a system and is a leak, the vacuum gauge will A. begin to rise. B. stay where it was when the vacuum pump S. A digital micron gauge A. is used to measure a vacuum in a refrigeration B. is used to measure atmospheric pressure. C. is used to measure the pressure in a refrigera- valved off C. begin to fall D. vibrate back and forth. tion system under normal operating conditions at the compressor discharge line. D, is uned to measure atmospheric pressure at sea 11. The best leak detection test is when the refriger. level. tion system is A. in a vacuum. B. open to the atmosphere. C. operating with all fans activated D. not operating but in a standing pressure 6. A micron gauge A. is used to measure atmospheric pressure at high clevations B. is used to measure atmospheric pressure at sea level. condition. C. is often used to measure a vacuum at less tharn 12. Moisture in a liquid state must be 1 mm Hg D. is used to measure pressure on the high-pressure side of an operating refrigeration system are microns in 1" Hg. before it can be removed with a vacuum A. vaporized B. condensed C cooled D, solidified 7 There B. 25,400 13. 1 Hg is equal to C. 10,000 D. 24,500 A. 1000 microns. B. 500 microns C. 25,400 microns. D. All of the above. 8. A deep vacuum involves reducing the pressure in a refrigeration system to approximately A. 200 to 500 microns. B. 400 to 800 microns C. 28 Hg D. 20 psig 14. At 15,500 microns, water boils at A. 64.47F B. 212 E C. 100°C D. None of the above. 9. A multiple evacuation means that A. you connect three vacuum pumps simultaneously to a refrigeration system and pull a vacuum B. you pull a vacuum on three different systems at 15. Which of the following may be used to protect the vacuum pump when excess moisture is in a system to be evacuated? A. Cold trap the same time C. you pull a vacuum on a refrigeration system more than once, allowing some dry nitrogen back into the system between each procedure. D. there must be more than one system operating B. Changing the vacuum pump oil often C. Using the gas ballast feature of the vacuum before a vacuum can be pulled pump D. All of the above.