Safety controls serve what function?

Safety controls serve what function?

a) They stop operation if the temperature gets too high.
b) They stop operation when the pressure gets too high.
c) They stop operation when the pressure is too low.
d) They stop operation when the temperature is too low.
e) All of the above





Answer: E

Which of the following actuating control valves is electromagnetically operated?

Which of the following actuating control valves is electromagnetically operated?

a) Thermostat valve
b) Fluid expansion regulator valve
c) Evaporator pressure regulating valve
d) Condenser cooling water regulating valve
e) Solenoid valve







Answer: E

Starting, stopping or unloading of the compressor is usually done by all of the following operating controls except

Starting, stopping or unloading of the compressor is usually done by all of the following operating controls except

a) temperature actuated control
b) viscosity activated control
c) pressure activated control
d) humidity activated control
e) All of the above can control the starting, stopping or unloading of the compressor.

Answer: B

The CSA B52 code requires that pressure limiting devices shall be provided on all systems operating above atmospheric pressure, except on a factory sealed system containing less than _____ of group A1 refrigerant:

The CSA B52 code requires that pressure limiting devices shall be provided on all systems operating above atmospheric pressure, except on a factory sealed system containing less than _____ of group A1 refrigerant:

a. 9 kg
b. 7 kg
c. 10 kg
d. 5 kg
e. 3 kg






Answer: C

The safety control that uses a current transformer with a resistor in the motor circuit is known as:

The safety control that uses a current transformer with a resistor in the motor circuit is known as:

a. High motor temperature cut-out
b. Low oil sump temperature cut-out
c. Motor overload protection
d. Low pressure cut-out
e. High oil temperature cut-out






Answer: C

With regard to their application in refrigeration systems, which of the following statements about flow switches is false?

With regard to their application in refrigeration systems, which of the following statements about flow switches is false?

a. They are used on chilled water systems
b. They are used as shutdowns or permissives when flow is insufficient
c. They are operated by the force exerted on a flexible vane immersed in the fluid flowing in the line
d. They can only be used to regulate liquid flow, not air flow
e. They can be used to close flow indicator circuits





Answer: D

A refrigeration compressor's oil pressure failure switch uses a _________ element as part of its operating mechanism.

A refrigeration compressor's oil pressure failure switch uses a _________ element as part of its operating mechanism.

a. Fluid expansion
b. Bimetallic
c. Thermostatic
d. Humidity activated
e. Volumetric






Answer: B

The oil-pressure failure switches of a mechanical refrigeration system

The oil-pressure failure switches of a mechanical refrigeration system

a. keep the compressor oil pressure at a level where the oil will not freeze
b. prevent compressor start-up if the oil heater fails
c. separate refrigerant dissolved in the oil from the lubricant
d. shut down the compressor when the oil pressure drops below the minimum required value
e. keep the oil from freezing at low pressure





Answer: D

An operating control, which consists of a hygroscopic element made of material similar to multiple strands of human hair, is called a:

An operating control, which consists of a hygroscopic element made of material similar to multiple strands of human hair, is called a:

a. Humidistat
b. Thermostat
c. Fluid expansion regulator
d. Pressurestat
e. Bimetal element






Answer: A

With regard to the high pressure side, the maximum setting for a pressure limiting device on a refrigeration system shall not exceed the pressure relief device setpoint by:

With regard to the high pressure side, the maximum setting for a pressure limiting device on a refrigeration system shall not exceed the pressure relief device setpoint by:

a. 100%
b. 75%
c. 90%
d. 80%
e. 50%







Answer: C

The expansion valve in a refrigeration system

The expansion valve in a refrigeration system

a. Expands the liquid to the receiver
b. Relieves high pressure in the receiver
c. Regulates the liquid refrigerant flow to the evaporator
d. Is used to charge the refrigeration system
e. Isolates the compressor from the condenser






Answer: C

With regard to a refrigeration system pressurestat, which of the following statements is false?

With regard to a refrigeration system pressurestat, which of the following statements is false?

a. The control is connected to the suction line of the compressor
b. The control consists of a switch actuated through a linkage arrangement connected to a bellows or diaphragm
c. A pressurestat can be used in conjunction with an automatic expansion valve
d. When the pressure drops to the minimum allowable the switch acts opposite to a thermostat and opens
e. A pressurestat cannot be used with a capillary tube

Answer: C

In many cases, the evaporator pressure of a refrigeration system must not fall below a certain level, in order to prevent

In many cases, the evaporator pressure of a refrigeration system must not fall below a certain level, in order to prevent

a. Frosting of coils
b. Evaporator valve lock
c. Tubing collapse
d. Overheating of the evaporator
e. Overheating of the compressor





Answer: A

The refrigeration compressor's operating control that uses a bimetal element is a:

The refrigeration compressor's operating control that uses a bimetal element is a:

a. Fluid expansion actuating control
b. Pressurestat
c. Humidistat
d. Temperature actuated control
e. Flow switch

Answer: D