Metering Devices

What is the primary function of all metering devices?

• To provide refrigerant to the evaporator.

• To prevent liquid floodback.

• To absorb heat energy.

• To charge the flux capacitor.

Which devices listed are metering devices?

• AEV.

• Capillary tube.

• PRV

• Solenoid

What are two ways the metering device accomplishes its primary function?

• Prevents floodback and evaporator flooding.

• Changes incoming liquid to a spray and lowers its temperature.

• Increases the evaporator pressure and superheat.

• Increases the evaporator subcooling and decreases evaporator pressure.

Can you use a pocket thermometer to calculate superheat? Why or why not?

• Yes, pocket thermometers are very accurate.

• No, they are not accurate enough for measuring line temp.

• What is a pocket thermometer?

• Yes, because they fit nicely in the holes located in refrigerant piping.

When checking system superheat when is the best time to take reading?

• When the space temperature is withing 5 degrees of design.

• On initial startup of the system.

• When the system is satisfied.

• The third Sunday after the full moon.

Why is superheat important in a TEV system?

• It keeps the temperature of the evaporator up so id doesn't freeze.

• It allows the evaporator to operate at its maximum efficiency.

• It acts as a margin of safety to prevent compressor damage.

• It keeps the compressor lubricated.

Select the metering device from below.

• Thermostatic Expansion Valve

• Electronic Refrigerant Vaporizer

• Refrigerant Bypass Valve

• Fixed Orifice

What are the three primary forces on a TEV?

• Head pressure, suction pressure and valve pressure.

• Bulb pressure, evaporator pressure and spring pressure.

• Bulb pressure, liquid line pressure and evaporator pressure.

• Hot gas pressure, suction pressure and bulb pressure.

What is the only opening force of a TEV?

• Spring pressure

• Evaporator pressure

• Bulb pressure

• Inlet pressure

How is the factory setting of the superheat adjustment determined on a Sporlan expansion valve?

• Adjust the stem all the way in until it stops.

• Find the midpoint stem position.

• Adjust the stem all the way out until it stops.

• Adjust the refrigerant charge.