4 replies to this topic

[fmalik]

Hello,
I'm seeking clarification on whether hydraulic resistance from piping and components (e.g., heat exchanger pressure drop) should be considered as a credit when calculating PSV relief rate for an upstream control valve failing wide open.

My system:
- Battery Limit Pressure: 18 Barg
- Control Valve: Reduces pressure to 1.5 barg
- Line: 10 ft
- Heat exchanger: specific pressure drop
- Packed bed: specific pressure drop
- Manual valves: ~80% open
- Blower (design pressure: 3 barg): PSV location

Should the relief rate account for all component resistances as flow increases, or should it be sized based on 18-3x1.1 pressure differential?​​​​​​​​​​​​​​​​

[latexman]

If it results in a smaller PSV, yes, include pipe and fitting resistance.

[fallah]

Hello,
I'm seeking clarification on whether hydraulic resistance from piping and components (e.g., heat exchanger pressure drop) should be considered as a credit when calculating PSV relief rate for an upstream control valve failing wide open.

My system:
- Battery Limit Pressure: 18 Barg
- Control Valve: Reduces pressure to 1.5 barg
- Line: 10 ft
- Heat exchanger: specific pressure drop
- Packed bed: specific pressure drop
- Manual valves: ~80% open
- Blower (design pressure: 3 barg): PSV location

Should the relief rate account for all component resistances as flow increases, or should it be sized based on 18-3x1.1 pressure differential?​​​​​​​​​​​​​​​​

 

Hi,

 

Yes, in general all components resistance would affect the PSV relief rate...

[breizh]

Hi,

The answer is Yes, all pressure losses should be considered.

Consider this handbook to support your work.

Breizh

Attached Files

•  pressure-relief-valve-engineering-handbook-en-in-4257520.pdf   9.33MB   23 downloads

[Chemitofreak]

Yes, one can take credit of the losses in the fittings and equipment.

 

My two cents:

1) If you are calculating for brownfield project, go ahead and consider these loss

 

2) If you are calculating for green field, do not consider these losses and do conservative calculations, because a lot of thing change and you might end up in re-doing the calculation at a later date.