Why might closing the oxygen cylinder, then the acetylene cylinder, then bleeding first the oxygen line, then finally the acetylene line at the end of a brazing project create a hazardous situation?
A) The acetylene and oxygen lines should be bled simultaneously.
B) The acetylene and oxygen cylinders should be closed simultaneously.
C) The acetylene cylinder should be closed first.
D) The last gas to go through the torch will be a flammable gas.
[Ques. 2] When the heat load on the evaporator increases, the automatic expansion valve:
A) Closes to keep the pressure from increasing.
B) Does nothing because AEVs are not modulating devices.
C) Sends a signal to the electronic control board indicating the change.
D) Opens to feed more refrigerant.
[Ques. 3] One operating advantage of fixed-restriction metering devices over expansion valves is:
A) Can be used with low starting torque compressor motors.
B) Higher operating efficiency.
C) Improved system control.
D) Easier to adjust.
[Ques. 4] What type of systems normally use crankcase pressure regulators?
A) Commercial refrigeration applications with evaporator temperatures above 40F
B) Any refrigeration system with a compressor that has a positive-pressure oil pump
C) Primarily comfort cooling applications
D) Low-temperature refrigeration applications such as walk-in and reach-in freezers
[Ques. 5] How do you know when to stop applying solder?
A) The solder will draw all the way around the joint.
B) The solder will run out of the top of the joint when it is full.
C) The solder will stop flowing into the joint.
D) When solder balls form on both sides of the joint, you are done.
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