mg test nov 2

automatic pump down systems are equipped with a what valve to prevent refrigerant from reaching the evaporator

solenoid valve

snap acting valve that open and close very fast with the electrical energy to the coil

solenoid valves

the one time relief valve is cased to relieve by

temp, hear or fire

what prevents the oil pressure safety control from DE energizing a compressor immediately after start up

time delay

define a king valve

valve that is at the outlet of the reciever with a diptube

what is a check valve

valve that only lets refrigerant to flow in one direction

random defrost is accomplished with

when the refrigeration system has enough reserve capacity to cool more than the load requirement

the refrigeration compressor motor can be operated at about what percent over its rated capacity without harm during this pulldown

10 %

what is the temperature range in medium temperature refrigeration

34 to 45

a suction line accumulator is used to ensure that liquid refrigerant enters the compressor

False

helical oil separators are about 98% efficient in separating oil

True

oil separation work on the principle of low refrigerant and oil velocity

True

the crankcase pressure regulator puts a limit on the pressure that can return to the compressor

True

two-temperature operation is desirable when more than one evaporator is used with one compressor

True

refrigeration systems are designed to operate year round for this reason they are equipped with

a low ambient control

where is the refrigerant sight glass normally located

after the filter dryer in the liquid line

which of the following is another type of low ambient temperature head pressure control?

air volume control using shutters and fan cycling

frequently on smaller condensing units, one fan will run continuously and the other fan will be cycled on and off

ambient temperature controller

the normal position for a suction service valve during normal operation

back seated

how does the receiver ensure that only 100% liquid refrigerant enters the liquid line?

by means of a dip tube

orit is what kind of valveq

cpr valve

to protect the compressor during periods of hot pull down, a what valve is used

cpr valve

what is the crot valve also called

cpr valve

what valve is a mechanical control that keeps the refrigerant pressure in the evaporator from going below a predetermined point

epr valve

what are the two forces that contorl the epr valve

evap pressure and valve spring pressure

which of the following is a type of low ambiet temperature head pressure control

fan cycling

list 5 methods of providing low ambient controls for refrigeration units

fan cycling, fan speed control, condensor splitting, condensor flooding, air volume control

defrost using internal heat is accomplished using

hot gas from the compressor

what does a cool liquid line filter dryer indicate

its blocked

what is the crank case pressure reg valve used for

keep the low temperature compressor from ovberloading on a hot pulldown

where is the refrigerant filter drier found

liquid line after the king valve

list four causes of liquid floodback

low evap loads evap fan frozen dirty evap coil evap fan not operating

to protect a refrigeration compressor when refrigerant loss occurs

low pressure control

the epr valve is installed in the suction line at the evaporator outlet and it?

modulates refrigerant vapor to the compressor. prevents the boiling point in the evaporator from dropping below a pre set point and when used with a tx valve the system has the characteristic of maintaining a constant superheat and keeping the pressure from going to low

two temperature operation of a refrigeration system is necessary when?

more than one evaporator is used with one compressor.

crot is special why

needs ammeter to adjust it

the spring loaded type of relief valve is normally brass with a what seat

neoprene seat

formula to remember

oil pump discharge pressure - crankcase pressure = net oil pressure

how can you tell if your float is stuck open on the oil seperator

oil return line

two types of relief valves are the spring loaded valve and the what valve

one time or fusible plug

epr valve are also referred to as what valve?

ori valves

what valve is used as a epr valve

orit valve

low ambient control valve

oroa valve

when a system pumps down, where is the refrigerant stored

receiver and the condensor