incorporate a temperature sensor inside the valve, and operate independently of external power supplies.
are powered by an external electric actuator, with control provided by a separate electronic control unit, and temperature sensing by resistance thermometer.
are powered by an external pneumatic actuator, with control provided by a pneumatic controller with external temperature sensing.
are designed to control refrigerant gas pressures – and hence the temperature of refrigerated or air-conditioned areas – in marine systems in which the condenser is cooled by sea water.
Click on the image below to view the animation. Click on the right hand 'warmer' or left hand 'colder' button located near the top of the images to scroll through the diagrams.