Refrigerant Basics
What is the name of the substance that circulates through an HVAC/R system to transfer heat?
Refrigerants
As the pressure of a refrigerant increases, what generally happens to its saturation temperature?
It increases
What color hose is traditionally connected to the low side of a standard HVAC manifold gauge set?
Blue
Which component is responsible for removing heat from the indoor space by allowing the refrigerant to evaporate?
The evaporator coil
What piece of personal protective equipment should be worn to protect your eyes when working with refrigerant?
Safety Goggles
What does the "R" in refrigerant designations such as R-22 and R-410A stand for?
Refrigerant
What tool or reference chart allows a technician to determine the saturation temperature of a refrigerant based on its pressure?
A P-T chart
What tool is commonly used to measure temperature on a refrigerant line?
A thermometer or temperature probe.
What are the components in proper order on the refrigerant cycle?
Compressor, Condenser, Metering Device, Evaporator
What can happen if liquid refrigerant comes into contact with your skin?
It can rapidly evaporate and cause frostbite
What happens to a refrigerant when it changes from a liquid to a vapor?
It absorbs heat
Why can't a technician assume that a pressure of 120 PSI corresponds to the same saturation temperature for every refrigerant?
Every refrigerant has a different PT relationship
What is the primary purpose of the manifold gauge set when servicing an HVAC/R system?
To measure system pressures and temperatures
What component reduces the pressure of the refrigerant before it enters the evaporator?
The metering device
Why should refrigerant cylinders be stored upright and secured?
To prevent them from tipping over and to help maintain safe handling and storage conditions.
What are the two physical states a refrigerant commonly changes between during the refrigeration cycle?
liquid and vapor
A technician measures the pressure of a refrigerant and then looks up that pressure on a P-T chart. What temperature is the technician trying to determine?
The saturation temperature
Why shouldn't a technician rely solely on refrigerant pressure to determine whether a system has the correct charge?
Pressure is affected by operating conditions.
Why is the compressor the most important part of the refrigeration cycle?
It is the motor or the "heart" of the system
Why should refrigerant cylinders never be heated with an open flame or torch?
Heating the cylinder can cause the pressure to rise dangerously and potentially cause the cylinder to rupture.
A technician finds an older system containing R-22. The system has a leak and needs refrigerant added. Why is simply replacing the R-22 with a different refrigerant without considering system compatibility not an acceptable procedure?
Different refrigerants can have different pressure-temperature relationships
A refrigerant's saturation temperature is 35°F. The actual temperature of the surrounding air is 75°F. In which direction will heat naturally flow?a
From the 75°F air into the 35°F refrigerant.
Why should a technician purge or minimize air in hoses when connecting charging equipment to a refrigeration system?
To prevent air and other non-condensables from entering the system
A refrigerant leaves the evaporator as a low-pressure vapor, enters the compressor, and leaves the compressor as a high-pressure vapor. What happened to the refrigerant's pressure and temperature across the compressor?
Both the pressure and temperature increase.
A technician is working on a refrigeration system in a small, poorly ventilated room. Why could this create a safety hazard even if the refrigerant itself isn't highly toxic?
A refrigerant leak can displace oxygen, creating an asphyxiation hazard.