When a spring pressure pilot is installed in series with a self-contained temperature pilot, the pilots perform their functions separately and concurrently. Each pilot regulation cycle is exactly the same as if used alone. When both pilots are open, the main valve will open. If either pilot closes, the main valve will close. The pressure pilot acts to limit the maximum downstream pressure as the temperature pilot cycles to control temperature.

A solenoid pilot and aquastat may be added as a temperature safety override control.

• A single main valve and pilot combination accomplish pressure reduction and temperature control.
• Self-contained system. No external power source required.
• Thermostatic bulb in sensed fluid guards against over temperature.
• For economical operation, main valve modulates to maintain set temperature.
• Controlling maximum pressure in the steam system limits the condensate temperature from steam traps to reduce flash steam loss.

Operation with Combination of Air Pressure and Pneumatic Temperature Pilots:

Pneumatic temperature control pilots may used in conjunction with air pressure control pilots to control temperatures in systems with rapid changes in the required heat load. An air-pressure-regulating valve is used to limit the pressure of the air supplied to the pneumatic temperature pilot. Limiting this air supply pressure limits the air pilot loading force and hence the steam pressure downstream from the main valve.

Combination of Air-Pressure and Pneumatic Temperature Control

Steam flows to the main valve only when both the pneumatic temperature and the air pilots are open. Steam flows through the air pilot seat and signal line producing steam pressure on the main valve diaphragm. The force from the steam pressure pushes against the main valve spring to control the main valve position. Variations in temperature are sensed by the temperature sensor, which acts to control the air signal to the air pilot. The air pilot in turn controls the position of the main valve, ensuring a constant temperature of the heated fluid or gas.

A solenoid pilot may be added as a temperature safety override control.