2 replies to this topic

[cmp74]

Hi all.

I have a project at hand where Im thinking of installing a pilot operated valve as the existing conventional valve is undersized and also inlet losses are much higher than 3% (close to 9 %).

The API orifice required is Q to meet relief load.

My question is what precautions should be taken with Pilot valves with large orifices? Is there anything different from smaller orifice Pilot valves?I have done many smaller pilot operated valves but not this big.

The process media is Natural gas.

Please give your opinions ...inputs.....

[ankur2061]

cmp74,

I had prepared a "Vent & Depressurization" standard for a middle east O&G company wherein there was a brief section devoted to applicability of Pilot-Operated Relief Valves. I am reproducing the same below:

Pilot-Operated valves are recommended for applications where the back-pressure on the valves are very high (typically 50% or higher). The other criteria for selecting pilot-operated valves are as follows:

a. Low accumulation rates are required.
b. The set pressure is required to be close to the operating pressure.
c. Calibration is required without removing the valve.
d. Handling of large relief flows are required.
e. The service is non-fouling.

Hope this helps.

Regards,
Ankur.

Edited by ankur2061, 21 November 2011 - 11:07 PM.

[fallah]

Hi all.

I have a project at hand where Im thinking of installing a pilot operated valve as the existing conventional valve is undersized and also inlet losses are much higher than 3% (close to 9 %).

The API orifice required is Q to meet relief load.

My question is what precautions should be taken with Pilot valves with large orifices? Is there anything different from smaller orifice Pilot valves?I have done many smaller pilot operated valves but not this big.

The process media is Natural gas.

Please give your opinions ...inputs.....

cmp74,

What do you mean by...what precautions should be taken with Pilot valves with large orifices?.....?

Do you mean mentioned large orifices to be oversized for some secenarios with small relief loads?

If so, and also considering high inlet pressure loss you must use modulating pilot operated PSV.

If you are not satisfied with this reply please clarify a bit more about your query.

Fallah

Edited by fallah, 22 November 2011 - 01:41 AM.