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Using a Relief Valve as a Pressure Regulator

06/15/2009 11:08 AM

I need to control a small flow 0.5 Liters /minute to 0,200 Barg , but backward the valve .

I use a small diaphragm pump rated at 0.5 liter/min at 0.7 Barg.

The pump take the air , then run it to a small chamber whre the pressure shal be sustain to the 0.200 Barg.

My idea is to suit the relief valve , to work open, at the outside of the chamber.

Size is mandatory , 10 mm diameter, 20 to 30 mm lenght .

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#1

Re: Using a relief valve as a pressure regulator

06/15/2009 11:47 AM

It looks good from here.

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#2

Re: Using a Relief Valve as a Pressure Regulator

06/15/2009 2:05 PM

I would consider using a storage tank and a pressure switch and build up a surplus of pressure so you can cycle the pump and allow for some cooling time. You could control your desired pressure more precisely with a regulator or dual stage regulator and not be generating the constant noise of air escaping through the over pressure valve. The system you have designed may cause the pressures to pulsate. In todays industry noise is taken very seriously and if you do use the over pressure valve be sure and use an air muffler. Jerrell

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#3
In reply to #2

Re: Using a Relief Valve as a Pressure Regulator

06/15/2009 2:35 PM

Hi Jerrel , noise is not an isue, it is used ouside on open country enviroment.

There is no room space to put any more than the relief valve 10 mm diameter.

Pulsation, it is a concern , but could be accepted.

The flow have to be continous.

It is a gas sample device.

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#4

Re: Using a Relief Valve as a Pressure Regulator

06/15/2009 3:50 PM

Used that circit several times. Was even in Hydraulics & Pneumatics Magazine in the Ideas & Applications section they ran.

The only problem I ever had was on a circuit that was subject to external temperature fluctuations. Reduced temperature was no problem, however when temperature rose air pressure could increase in the blocked reduced portion of the circuit in relation to the temperature change. That was only a problem when the reduced pressure must be held for long periods.

The other reason for the pressure to increase is when the Seat and Poppet seal in the pressure control does not have ayy bypass. Any bypass into the reduced pressure chamber will cause a pressure rise over time.

In hydraulic circuits I always used a Poppet Design with a known good seat and even on Air-Hydraulic Booster circuits you could have Reduced Pressure on one actuator like a clamp while the Punch Cylinder could use full pressure/force.

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#5

Re: Using a Relief Valve as a Pressure Regulator

06/15/2009 6:06 PM

It occurred to me that it might be advantageous to arrange some sort of buffering in order to give you more stable pressure control. You might connect into the circuit a vessel with a relatively large volume.

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#6
In reply to #5

Re: Using a Relief Valve as a Pressure Regulator

06/15/2009 7:37 PM

Hi Techie,

Welcome to the loony bin technical forum.

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#7
In reply to #5

Re: Using a Relief Valve as a Pressure Regulator

06/15/2009 7:54 PM

As I stated before , room space does not allow more than the valve.

It work for a short time , while the air-gas mixture is analised.

Thanks for all your´s help.

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#8

Re: Using a Relief Valve as a Pressure Regulator

06/16/2009 7:49 AM

I would use a pulsation dampener, installed right after the pump discharge, especially if the metering pump is operated by a solenoid. Pick the dampener with a volume approximately 20-30 times the stroke volume of the metering pump.

Don't forget to install a pressure gauge right before the backpressure valve, so that you can see the pressure while you are adjusting the valve, and make sure that the valve is suitable for your operating pressure.

The pump should be able to run dry forever without overheating.

Good luck.

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BudT (1); devitg (2); Jerrell Conway (1); lyn (1); PWSlack (1); SardMan (1); Techie (1)

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