Thermal Expansion Block Valve

 

Thermal Expansion Block Valve

 

 Thermal Expansion Block Valve

The block valve differs from the previously

mentioned expansion valve in that it has four

passages, although the basic operation is

exactly the same. Operation of the block

valve is still via refrigerant

expansion/contraction within a diaphragm

(11), but not sensed through separate tube

(capillary tube). It is sensed by changes in

the refrigerant temperature and pressure

passing from the evaporator outlet through

the block valve.

As the refrigerant from the outlet side of the

evaporator passes over the sensing element

(12), expansion or contraction of the

refrigerant takes place causing the activating

pin (8) to move the ball valve (6) away or

closer to the metering orifice. This allows

more or less refrigerant to enter the

evaporator coil inlet.

 

1. From Filter Drier

2. To Evaporator Inlet

3. From Evaporator

4. To Compressor

5. Metering Orifice

6. Ball

7. Spring

8. Activating Pin

9. Refrigerant

10. Pressure Compensation

under Diaphragm

11. Metallic Diaphragm

12. Sensing Element

 

 

 

Pressures in control

As shown in the illustration, the block valve

controls refrigerant flow by using a system of

opposing pressures which we will call:

F1 - Temperature sensing

This is a sealed diaphragm and sensor

containing refrigerant. As refrigerant leaving

the evaporator coil outlet passes over

sensing element (12) the refrigerant (9)

above the diaphragm (11) expands moving

pin (8) downwards pushing ball valve (6)

away from the metering orifice (5).

F2 - Pressure compensation

This is a passage (10) in the block valve

outlet side where refrigerant can build up

under the diaphragm (11) to act as an

opposing pressure to help regulate the

amount of refrigerant into the evaporator coil

inlet side.

F3 - Pressure spring

This spring (7) is located under the ball valve

(6) and acts as an opposing force trying to

move the ball valve towards the metering

orifice (12) and to reduce refrigerant flow to

the evaporator coil inlet.

 

kandi younes