CARO Refrigeration Controls and Instrumentation

Question 1

What is the primary purpose of a high-pressure cutout switch in a refrigeration system?

Accepted Answer

To shut down the compressor when discharge pressure exceeds a safe limit

Answer

To increase system efficiency

Answer

To regulate suction pressure

Answer

To control condenser fan speed

Question 2

Which instrument is used to measure both suction and discharge pressures simultaneously on a refrigeration system?

Accepted Answer

A manifold gauge set

Answer

A thermometer

Answer

A manometer

Answer

A hygrometer

Question 3

What does a solenoid valve do in a refrigeration control circuit?

Accepted Answer

Controls refrigerant flow by opening or closing electrically

Answer

Measures refrigerant temperature

Answer

Regulates compressor speed

Answer

Monitors oil pressure

Question 4

A thermostatic expansion valve (TXV) senses which two conditions to regulate refrigerant flow?

Accepted Answer

Evaporator outlet temperature and suction pressure

Answer

Suction pressure and oil level

Answer

Discharge temperature and condenser pressure

Answer

Compressor speed and refrigerant charge

Question 5

What is the function of an oil pressure safety switch on an ammonia compressor?

Accepted Answer

To shut down the compressor if oil pressure falls below a safe minimum

Answer

To maintain refrigerant charge

Answer

To regulate discharge temperature

Answer

To monitor refrigerant purity

Question 6

What does a pressure-temperature (PT) chart help a refrigeration operator determine?

Accepted Answer

The saturation temperature corresponding to a measured refrigerant pressure

Answer

Compressor amperage draw

Answer

Evaporator airflow velocity

Answer

Oil viscosity at operating temperature