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Massachusetts Refrigeration Test with Questions and Answers Which is an organic refrigerant ANSWER VV R-717 Which refrigerant is lighter than air ANSWER VV 717 Which occupancy classification can ammonia be used it ANSWER V V Depends on the quantity The purpose ofa receiver is ANSWER V ¥ To increase the capacity that a system can hold Tlow do you find the net oil pressure on a compressor ANSWER VV Gross oil pressure- suction pressure What is the minimum height of Freon piping in an open space? ANSWER VV 7.25' What will happen if "purging" is not done in a Freon system ANSWER V ¥ Iligh pressure Systems in low temp applications should use what type of oils ANSWER V/V Low pour point What device should be used on low temp freezers ANSWER V/V Oil separator What type of metal is not suited for ammonia systems ANSWER VV Copper When a pressure gauge is permancnily installed on a system it must be times the system's design pressure. ANSWER VV 1.2 Copper piping must be before it is buried ANSWER V J Encased What is the temperature of a solder joint within an air duct ANSWER V/V 700 If a thermometer is placed at the outlet of the compressor, it will only measure: ANSWER V ¥ Sensible heat Onc horsepower is equal to watts ANSWER VV 746 How is brine measured ANSWER V J Hydrometer The low pressure oil switeh will ANSWER VV Shut down the compressor What is the heat called when the substance changes state ANSWER V V Latent heat. Positive displacement compressors with a stop valve on the discharge linc, must have what before the stop valve ANSWER VV High pressure control A compressor in which the increase in pressure is attained by changing the internal volume of the compression chamber. ANSWER V V Positive displacement compressor A liquid used for the transmission of heat, without a change in state and having no Flash point, or a flash point above 150° F is known as: ANSWER VV Secondary coolant Stop valves shall not be permitted between the system and the: ANSWER VV Relief valve Pressure relief valves shall be marked with data from ANSWER V V Section VIII Division 1 of the ASME boiler & pressure code Liquid receivers shall not occupy more than _%volume when the temperature of the refrigerant is 90°? ANSWER V/V 90 112. The total amount Freon to be stored in the machine room (not including the Freon in the system) ANSWER VV 330 How many forces operate a thermostatic expansion valve? ANSWER VV 3 How many opening forces operate a thermostatic expansion valve? ANSWER VV 1 How many closing forces operate a thermostatic expansion valve ANSWER VJ 3 When an electronic bridge is in balance, the bridge output will be? ANSWER VV Ov An electronic bridge is basically? ANSWER VV Wheatstone If two 500 ohm resistors are wired in scrics the total resistance will be? ANSWER / 4 1,000 ohms The equation for ohms law is ANSWER VV volts= amps X ohms Single Pole Double Throw Switch requires(not including ground) ANSWER V J 3 wires A micron is ANSWER VV One thousandth of a millimeter Refrigerants shall be classified by ANSWER Vv toxicity, flammability Which creates more of a heat load ANSWER V ¥ 90% RH When the compressor is below the condenser ANSWER VV Traps are needed on the discharge line When the condenser is located outside, what must be done for proper winter operation ANSWER V ¥ Fan speed cycling The oil separator is always inserted in the system ANSWER V ¥V In the discharge line On an ammonia system if the pump fails it will? ANSWER VV Shut the compressor off 
