Chapter 118 Flashcards
The operation of the compressor is usually accomplished by the following types of actuated controls:
Temperature, pressure, humidity
Temperature actuated valves can be?
direct or indirect type
Actuating or secondary controls are used to indirectly control changes in operation which are called for by?
primary controls
Where would the evaporator pressure regulator be installed?
evaporator outlet
Hygroscopic element made of material similar to multiple strands of human hair is called
humidstat
A refrigeration oil pressure failure switch incorporates a _______ element.
bimetallic
The safety control which uses a current transformer with a resistor in the motor circuit is known as
motor overload protection
Evaporator pressure cant drop below a certain level or ________ will happen.
frosting of coils
What happens when the evaporator temperature rises?
the compressor suction pressure rises
What three controls regulate the starting and stopping of refrigeration compressors?
Temperature, humidity, and pressure actuated controls
What three safety and limiting controls will shut down a compressor?
Low limit thermostat, oil pressure failure switch, high oil temperature
What causes the cooling water regulating valve in a refrigeration system to open and regulate flow?
compressor discharge pressure
What cannot be used in conjunction with an automatic expansion valve?
pressure-stat
What is the purpose of the the expansion valve?
regulate flow to the evaporator
Pressure limiting devices shall be provided on all systems containing more than?
9 kg of refrigerant
