Unit 24: Expansion Devices

Expansion Devices

• Divide the high and low sides of the refrigeration system

• Meter the correct amount of refrigerant to the evaporator

• Installed in the liquid line at the inlet of the evaporator

• all of the above

The following is not an example of an expansion device

• Automatic expansion valve (AXV)

• Thermostatic expansion valve (TXV)

• Fixed bore (capillary tube)

• Rotary expansion valve (RXV)

Why is superheat necessary in a TXV?

• Superheat ensures that no liquid refrigerant leaves the evaporator.

• Superheat makes the condenser compress refrigerant.

• Superheat ensures that the refrigerant boils.

• Superheat is not necessary in a TXV.

What are the components of a TXV

• Sensing bulb and transmission tube

• Diaphragm

• Needle and Seat

• Spring

• All of the above

The valve body is made out of:

• Aluminum

• Brass or Stainless Steel

• Copper

• Iron

The Diaphragm

• Moves the needle in and out of the seat in response to system load changes

• Made of thin, flexible stainless steel

• Located at the top of the valve

• All of the above

The greater the pressure difference across the needle and seat, the _____________ the amount of flow through the valve.

• lesser

• greater

• same

• The pressure across the needle and seat does not affect the amount of flow through the valve.

_______________pressure determines the evaporator superheat; factory set to maintain between 8°F and 12°F of superheat in the evaporator.

• Head

• Air

• Spring

• Temperature

One side of the ______________ gets its pressure from the ________________, and the other side gets its pressure from the evaporator and the spring.

• needle and seat

• diaphragm and sensing bulb

• temperature and pressure

• metering device and compressor

The __________________________________ Controls refrigerant flow by the pressure drop across it

• RXV Metering Device

• AXV Metering Device

• TXV Metering Device

• CapillaryTube Metering Device