Description

An expansion valve is a device in steam engine valve gear that improves engine efficiency. It operates by closing off the supply of steam early, before the piston has travelled through its full stroke.

• Flow control, or metering, of the refrigerant is accomplished by use of a temperature sensing bulb, filled with a similar gas as in the system, that causes the valve to open against the spring pressure in the valve body as the temperature on the bulb increases.

•  As the suction line temperature decreases, so does the pressure in the bulb and therefore on the spring causing the valve to close.

• An air conditioning system with a TX valve is often more efficient than other designs that do not use one.