Flow Control Valve or Pressure Regulator?

Irrespective of names, all valves are "flow control valves".

Some valves are on/off. Some are modulating. Some are pressure control valves. Some are pressure relief valves, etc. etc.

It's the job that the valve does that determines its selection.

The type of valve could be a ball, butterfly, non-return, gate, globe, non-return, pressure reducing, etc.

So it's semantics, really.

Thanks, that's what I thought and all my testing seems to corroborate that as well. If I install a "pressure regulator" in-line and monitor flow downstream, there is clearly a direct linear correlation. If I install a "flow control valve" in-line and monitor pressure downstream I see the same results.

It's a long way from linear!

From the limited testing I've done with a limited amount of hardware, the relation seems linear. That could also just be due to the operating parameters I'm working with. It's not perfectly linear but very predictable. Either way, thanks for the response.

PW has it right. Pressure and flow relationships are not linear. Don't confuse this though with linear flow control valves... which provides a near linear function for flow vs. percent open for the valve (ie 25% open = 25% full flow, 50% open = 50% full flow, etc). That said, what goes on with pressure when flow is changed is as PW says, is far from linear.

The way I like to think of most valves is that they are used to control the amount of headloss in a system. And as PW said, the function the valve serves in the system determines what we call it, but boil it down and most simply adjust the headloss in piping in order to serve that purpose.

Correct, it is NOT linear, and they will behave differently.

There are many types of flow control valves, and pressure control valves. Proper care should be taken to select the correct valve for the application.

Flow control valves in hydraulic units normally allow full flow in one direction and limit (or cushion) flow in the opposite direction. For a piston lifting a lot of weight the pressure is controlled by a regulator. When the fluid enters the cylinder it is at maximum flow and regulated pressure. The flow control valve on the exiting side of the cylinder regulates the speed at which the fluid exits, thus keeping the speed of the action at a constant.

You may want to check out this link for an industry leader who has manufactured flow control valves sine 1879 (?), from Troy, New York:

www.rossvalve.com

Basically, their line of flow control valves that are a very simple, reliable, and resilient design incorporating a globe valve featuring a hydraulically operated "pilot" with orifices and solenoid(s), depending on the main function of that valve. Their website discusses how the various valves operate and their limitations. Lots of technical data is featured, although their hard copy catalog features more in-depth information.

I've used their valves (almost exclusively) over my career in the water and wastewater fields from pressure sustaining valves, pressure relief valves, flow rate controlling valves, level control (primarily in elevated water storage tanks...ie, altitude control valves), etc and the various combinations of pressure and flow rate control valves. Mainly my use of them has been for sustaining pressure in water system networks where there is a lot of hilly terrain within a city-wide network to prevent over-pressurization of the network as well (as to protect homeowners and business' building plumbing and hot water tanks) located downstream and downhill of control valve station.

Where I served as a City Engineer for a small upstate city, we had no less than 16 of these control valves within our water supply network,mostly located in underground vaults in the streets, together with at least 1/2 dozen flow control valves found along our approximately 23-mile (?) long 42-inch diameter raw water transmission line that was fed by 6 independent water storage reservoirs located up in the foothills of the Adirondacks, all primarily built before 1910. They were surprisingly simple to operate and maintain.

Of course there are other manufacturers of similar control valves, such as Cla-Valve (see link below). You'll find that either manufacturer will provide to you the necessary technical information you seek.

www.cla-val.com

Have fun searching their websites, and have a great day!

Flow control, pressure control or level control, its all similar for valve operation. The only difference is what is to be controlled and where?

For flow control, feedback is required from flow element where it measured. If flow is increasing valve will automatically close more to maintain required flow. This action will increase pressure in upstream of valve (which is tolerable). In case of pressure control, feedback for valve operation shall be from upstream/downstream pressure transmitter. If upstreams pressure is to be controlled, valve will open more for increased pressure to maintain required pressure, in case of downstream it will start closing. Level control valve installed at inlet of liquid tank will open more if level is reducing, but if installed at tank outlet it will close more to maintain required level.