Proportional Pressure Control
Proportion-Air electronically operated valves and regulators provide proportional pressure control of most fluids, inert gases and some hazardous media. Low pressure, high pressure and vacuum proportional pressure control devices are available.
Low Pressure Proportional Control
What is Proportional Pressure Control?
To control pressure “proportionally,” a variable electronic signal is used to provide a command to a pneumatic or hydraulic pressure control device. The electronic command signal (0-100%) is proportional to the calibrated pressure control range (0-100%).
In other words, a min-to-max electronic signal is proportionally equal to a min-to-max output pressure.
For example, the QB3H can be controlled with an electrical voltage or current signal. As shown here, the QB3H is setup to accept a command signal of 0-10 VDC. This equates proportionally to a controlled pressure range of 0-500 PSIG.
If a customer wants to control pressure downstream at 250 PSIG, they would simply provide the QB3H with an electrical command signal of 5 VDC. This tells the device to open the inlet valve until the internal sensor measures 250 PSIG.
With a 50% command of 12 mA to each of the MPVs, a 50% output pressure will be achieved in each separate process. This is proportional pressure control.
For example, the QB3H can be controlled with an electrical voltage or current signal. The QB3H shown is setup to accept a 0-10 VDC command signal which equates proportionally to an output pressure of 0-500 PSIG.
In this example, a 5 VDC command will tell the QB3H to open the inlet valve and increase pressure until 250 PSIG is acheived.
This example shows three Proportion-Air MPV pressure regulators mounted on a manifold and sharing a common supply pressure and common exhaust port. The MPV uses a “true” proportional valve and each of these are controlling a completely different pressure range with independent 4-20 mA command signals.
A 12 mA command signal (50% of span) can be applied to each MPV to achieve pressure output of 50% of each pressure range. This proportional pressure control works the same for 0%, 100% or anywhere in between.