3 replies to this topic

[rajeshrajan]

Dear Friends,

 

For the Ethanol dosing (PD) Positive displacement pump, i have the following pressure protection on the pump discharge:

 1) Primary pressure control and relief is through a Fail open, (PFM)Pressure and Flow modulating valve. (Please refer attached document).

2) Secondary pressure protection is the pressure relief valve internal to the pump.

 

 

Then, my question is:

1. Do i require an additional  Pressure relief valve (PRV) for the blocked discharge case, as the PFM valve provides pressure control and relief as well.?

2. What do API or best industry practise recommends in a similar scenario?

 

 

I would appreciate your inputs.

 

Thanks,

Raj

Attached Files

•  brochure-pfm-system.pdf   852.14KB   12 downloads

[fallah]

Raj,

 

Internal PRV as secondary over pressure protection layer can no longer protect the pump against failure due to blocked discharge over pressure, because it's a small PRV with a limited capacity that can protect the pump by internal recirculation only in the case of short term blocked discharge. Then, if such PFM valve has a PFD (probability of failure on demand) value equal to or lower than a PRV, it can be applied as the main protection layer otherwise you have to apply a PRV at the pump's discharge line...

[rajeshrajan]

Thanks Fallah for your prompt response. I am leaning more towards providing a PRV as this stage.

 

However, just out of curiosity if i go on the other option, am i correct in saying that the  PFD value can be found:

1. from the valve vendor

2. undertaking a SIL study.

 

Is there any other ways you suggest....

 

Regards,

Raj

[fallah]

Raj,

 

I don't know the way other than two ones you mentioned...