Low Pressure Electronic Regulator

Controlling ultra low pressures in the inches of water, pascal, and millibar range can be quite difficult with traditional spring loaded regulators. The primary reason for this is due to how challenging it is to get valve parts to move with such low pressures. Using an electronic pressure regulator to control these pressures is a surprisingly accurate alternative. These electronic valves work by using a sensitive pressure transducer to sense minute changes in pressure and adjust the gas input and exhaust using solenoid valves. This method allows us to make much smaller adjustments in pressure than with a traditional regulator.

Method of Operation

The QPV electronic pressure regulator accepts an analog voltage (0 – 10V) or current (4 – 20 mA) signal. The unit will control proportional to the signal received. For example, with a 0 – 10 V = 0 – 1 psig / 68 millibar(g) unit, giving the unit a command of 5V tells the unit to go to 0.5 psig / 34 millibar(g) and giving the unit a command of 10V tells the unit to go to 1 psig / 68 millibar(g). Similarly, with a 4 – 20 mA = 0 – 1.0 psig / 68 millibar(g) unit, giving the unit a command of 12 mA tells the unit to go to 0.5 psig / 34 millibar(g) and giving the unit a command of 20 mA tells the unit to go to 1.0 psig / 68 millibar(g).

You can control the unit using your own PLC (programmable logic controller), a data acquisition device such as a DAQ with software such as LabVIEW by National Instruments, or even just a simple potentiometer (variable resistor).

Accuracy & Repeatability

The QPV series electronic pressure regulator has calibration ranges as low as 0 – 2 in H₂0 (0 – 500 Pa, 0 – 5 millibar(g)) with an accuracy of +/-0.25% of full scale calibration for pressure ranges above 1 psig / 68 millibar(g) and an accuracy of 1% of full scale for pressures ranges 1 psig / 68 millibar(g) and below.

The QPV1 will go to the desired pressure accurate to within ±1% of full scale calibrated range (for pressures below 1 psig / 68 millibar(g)). However, the repeatability spec of ±0.2% may be more applicable. This means that when given the same command, the unit will always be within the ±1% range of pressure, but will also be within 0.2% (of full scale) of the same pressure.

For Example: A 0 – 500 Pa calibrated unit.
Accuracy: Command of 5 VCD (or 12 mA) tells the unit to go to 250.0 Pa. It could land anywhere between 245 Pa and 255 Pa for an accuracy of +/- 5 Pa.
Repeatability: Say the unit hits 250.625 Pa, it will always be within ±0.2% of that number or, ±1 Pa. Very repeatable.

Below are some example calibration ranges and their associated accuracies and repeatabilities.

Note: These are just example calibration ranges. The QPV can be calibrated to any pressure range from as low as 0 – 2 in H₂0 (0 – 500 Pa, 0 – 5 millibar(g)) to as high as 0 – 150 psig (0 – 1000 kPa, 0 – 10 bar(g)).