Another type of two-temperature valve temperature control. It is built like a thermostatic expansion valve and work in the same manner. He works with evaporator temperature or the temperature of the air inlet or outlet. He has a capillary tube and sensitive lamp like a thermostatic expansion valve. Bellows moves stem as at different pressures are created in the sensing bulb.
If the evaporator becomes cool enough, cooling sensing bulb lowers pressure in furs. Bellows then contracts. It pulls the plunger valve and valve cuts off. The valve is closed, the pressure will not be able to delete any lower in the evaporator. Then, control valve minimum temperature of the evaporator.
As evaporator warms, as well sensing bulb. The increase in pressure is transferred to the bellows. It expands, pushing the plunger so that the valve opens. The faucet is opened, the compressor, once again draws the evaporation of the refrigerant from the evaporator. This type of valve is always on the suction line of the warmest of the evaporator.
Fig.
13-118 shows that the regulator reacts to temperature of air. He does so as the air leaves the evaporator and flows into the instrument or event. He may also respond to the air temperature at the inlet of the evaporator.
It has a sensitive element in this air flow. Valve housing is mounted in the suction line. A liquid line connection is also made to the valve body. This provides the pressure needed to open the main valve TPR (temperature, pressure regulators).
As a temperature sensor bulb heats the rise in pressure in the closed small valve. Then on the high side pressure in the valve decreases. This allows the main piston to open the suction line more. As sensing the lamp is cooled, high pressure pilot valve is open. The main piston is forced down, closing the suction line pass partially or completely (modulates).
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