Controlling the pressure of air over molten metal to extruder furnace is easily achieved with a single-loop Proportion-Air pressure control assembly.

In this application, a QB1 mounted on an RM-Series volume booster is controlling pressure in the transfer of molten metal to an extruder furnace. Since this is not a “high accuracy” application, the Proportion-Air pressure control assembly can be single loop, instead of dual loop.

In single loop configuration, the QB1 controls pressure to the dome of a pilot operated regulator. The purpose of this is to increase flow into the process. But since the QB1 is only “closed-loop” around the dome pressure, the process pressure is subject to the hysteresis and mechanical inaccuracies inherent in the volume booster.

In this case, the RM-Series volume booster is a high performance pilot operated regulator. This single loop assembly will flow up to 2,000 SCFM with accuracy of ±1-2% of full scale calibration.