Hello, I want to know if it is

[Alma X]

Hello,

I want to know if it is possible to regulate the pressure inside an equipement by an upstream valve controlled by a pressure controller?
i.e. if the pressure drops the pressure transmitter sends a cosign to the controller which open the valve?

Thank you

 

[EdStainless]

Remote sensing regulators are common. In many you can run a sense line from where ever you like to control the outlet pressure and do it all pneumatically. It can also be done with sensors and control valves, just watch the system tuning.

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P.E. Metallurgy, consulting work welcomed

 

[1503-44]

Yes. But I would think about using the opposite signal. Operate with the valve open then close the valve when the downstream vessel is reaching its operating pressure.

 

[Alma X]

Thank you for your response.

In fact I can't close the valve, I need this flow continuously, I just want to have a constant pressure inside the vessel.

 

[1503-44]

You wrote this.

if the pressure drops the pressure transmitter sends a cosign to the controller which open the valve

I would do it this way.

Valves pressure control valves operate by adjusting their position between full open and full closed. You can define a "set pressure". which the highest operating pressure you want to have. When your vessel has any pressure lower than that set pressure, the valve will be fully open. When pressure is rising to equal the set pressure, the valve will begin closing. If the pressure in the vessel starts to go over the set pressure, the max vessel pressure, the valve will close. This method controls pressure going to the vessel and protects the vessel's pressure from getting too high and potentially exploding.

By proper selection of the valve, you can also make the valve give you a "target pressure" when it is, for example, 60% open. When pressure is above target pressure, the valve will close a little and pressure will go down to the target pressure. The valve will never be fully closed until pressure reaches the highest possible operating pressure, the "set point" as we defined above. When pressure is lower than target pressure, the valve will open a little and pressure will rise to target pressure. When pressure is very low, the valve will be fully open.

It is just a matter of selecting the valve with the correct characteristics.

That method described above will protect your vessel from overpressure.

You could do almost the same thing using a "target pressure" as "set point". Opening the valve to 60% when pressure is less, and closing the valve to 60% when pressure is high. It requires that you select the valve correctly. Note that the vessel might not be securely protected, because it depends on at what pressure the valve fully closes. If the valve is not fully closed before the pressure reaches the vessel's maximum operating pressure, it might endanger the vessel, as the set point is independent of vessel max pressure.

If you need to protect the vessel, it is also possible with the above to set another high pressure shutoff. When reaching that pressure, the valve will close. You may also need a relief valve on the vessel, just in case the pressure rises too high and the valve fails to close.

What you must do depends on if securely protecting the vessel is important or not. Proper valve selection, choosing the set point and determining the pressure drop at operating point and the resulting operating pressure are all very important.

 

[LittleInch]

Alma,

What you are asking is a very basic question and one that is very commonly solved with pressure regualtors. Some act electronically, others by pneumatic built in controls.

If you have a gas supply in your house or ever used a bottled gas supply, there is a regualtor which controls downstream pressure automatically. It's that thing with a flat circualr element on top of the valve.

Your response though makes no sense - To get a constant pressure the valve will need to close to control this pressure.

Now without further data it is not possible to comment, but this implies that you only have an on/off valve and not a control valve? You can do it this way, but the valve either opens and closes a lot of times or the pressure will fluctuate between an open (low) pressure and a close (high) pressure. Can be done, but a control valve as described by my friend mr 44 is one which is normally used.

Or if your pressures and flows are constant, you might be able to use an orifice plate or restriction orifice to match pressure drop and flows.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.