Pressure Flow Control vs Pressure Regulator

What does the user want - constant pressure at the system inlet? If so, a pressure regulator will work fine. The device admits air into the downstream system and closes shut when a set pressure is achieved. It opens again as users connected to the main draw air from it and lower its pressure.

Pressure regulator works on different mechanism. Pressure flow control device is available commercially as choke valve while pressure regulators are available as pressure regulator that are used in Gas cylinders.

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In electronics we use a voltage regulator (which would be equivalent to your pressure regulator) For what the company wants, we would use a current regulator.

Your pressure regulator is going to hold pressure at so many pounds per square inch at its output. If you break the air line at that point, it will spew out air in great quantities "until the cows come home" or until the air compressor runs out of air.

Your "Flow control device" will only let so many cubic feet of air pass a given point in a given time... no matter what the pressure is. I eliminated the word "pressure" because it is not relevant in describing this device. Its output is measured in cubic feet per minute... or cubic meters or whatever...per minute, second whatever.

If you break the air line at that point, it will still spew out air, but at the limited rate defined by the device... Hopefully the compressor has enough power to handle the break and supply air to the rest of the system too.

Now usually, I am using pneumatic (or hydraulic) concepts to explain voltage and current but hopefully this might help you.

Bill

Good answer, if the question was "flow" Vs. "pressure". Only problem is that he is talking about "pressure flow" . Which is a combination of both as I understand it. I maybe wrong though...

Wangito.

It's difficult to control the flow of gases except by controlling the pressure. High, constant pressure on one side flowing through an orfice is about the only way to get control of gas flow, and even then it's shaky.

Typically, a pressure flow control device is a combination pressure regulator and restriction, to control flow even when the upstream pressure changes.

A regulator only controls pressure, and will flow as much as needed to maintain the pressure.

Tad

I've only had a couple of years dabbling with pneumatics/hydraulics components, but it was long enough to teach me that different people call the same thing by different names. Since you are the one designing the system, you should know the operating characteristics of the regulator that you selected. Explain the function of your regulator to your customer. They should be able to tell you if it will work, or if not what needs to be different. I'm sure that whatever they are looking for, someone makes it. You just have to figure out what the manufacturer calls it!

I used to control air cylinders by connecting a pressure regulator to the compressed air source and the flow control regulator to the exhaust of the air cylinder. The pressure regulator controls the force on the piston and the flow control regulator controls the speed that the piston moves.

If the force on the piston does not need to be reduced from the force that is developed from the source line pressure then a pressure regulator is not needed.

I don't know if your flow control device is controlling a cylinder so this may not be applicable.

Yes there is a slight difference in Compressed Air terminology.

There is something called " Compressed Air Equipment" - This comprises of a Filter W/without auto drain + Regulator + Lubricator. Normaly known FRL Equipment also.

FRLA = Filter with Auto Drain + Regulator + Lubricator.

FR = Filter + regulator

R = Just regulator

FL = Filter = Lubricator

They range from 1/4" size thru 2" and installed close to the machine.

Further specification is then given on the Filter element 1/2/5 micron etc.

On Regulator(Pressure Regulator) spring range/ colour specified.

When you talk about Pressure Regulator on Air - we understand you want a Pressure Regulator out of a "Compressed Air Equipment". Pressure Regulators are max. 2" & scrwed.

When you talk of pressure flow control device , this we take as an Air Pressure Reducing Valve (PRV) pilot operated (a 1/4" pipe sensing downstream to maintain pre-set downstream air pressure).PRV can go over 4" & flanged.

Normally PRV are installed on Main lines and all branch lines of various sizes 1/4" thru 2" coming down from main lines are to be installed with each FRL or FR or just R.

This is because the compressor may be at say 120 psi yet your Plant does not need over 80 psi so installing a PRV on main line will save power. Then each lines to different machines may be having different operating pressure 20 psi/ 30 psi/ 50 psi etc., therefore, individual pressure regulators(R) takes over. The F(filter)prior it is to safeguard against moisture. If air is going to a Cylinder then a Lubricator is installed hance, FRL unit.

You need to specify PRV pilot operated. Inlet Pressure. Outlet set Pressure & Capacity m3/hr. The PRV will then be sized as per the capacity chart.

That was me Ducon, i forgot to long in.

hance is hence,.Sorry

Log in - sorry again .##*&$###&** am getting old.

If you install a pressure regulator in one direction it will control the the upstream pressure . Turn it around and it will control the downstream pressure (backpressure regulator).

Really! No joking. No seriously I need to know about this perfectly.

Does it also work with Steam PRVs?

If I turn around my steam PRV will it work as back pressure regulator too?

Does this then become "Surplussing" Valve?

I've a Spirax DP 17 , 2" set at 4 bar with inlet 10 bar with pilot pipe sensing downstream. Now if I reverse this and sense upstream it will maintain 10 bar?

Yes, it will work on steam up to 25 bar & 232 dec. C (but not both). The 2" Spirax DP17 you have now will require a pilot valve attached to it's side to do what you wish. I suggest you visit: www.spiraxsarco.com/pdfs/im/p100.13pdf for the complete specification and installation details.

I have a pressure regulator with a vent hole that when set at 90# lets out the 120# tank air pressure until equal. I looked if the arrow was backwards. Your statement that it will work backwards is what I'm looking for a steady 90# for my nail gun instead of letting the air out of my tank making my compressor run to keep up with the constant bleed. Do I understand your right?

Sure will. A regulator (downstream pressure control) is nothing more than a control valve and a pressure transmitter in one package. Likewise a backpressure regulator (upstream pressure control) is nothing more than the valve and transmitter sensing upstream pressure.

The reasons for selecting seperate components are: temperature, corrosion, erosion, high flowrate, viscocity etc.

Thanks buddy.Very soon am coming across this application for the first time. My Boiler is dropping down from 10 bar to 4 bar during certain hours when there are peak loads and I've adviced the Client to install a Steam accumulator parallel it. Once this is done I'll need the surplussing valve to sense upstream and maintain pressure at 10 bar. Rest selection & sizing + application of PRV am a pro.

Thanks again.