7 replies to this topic

[shahidulislam48]

Hello,

Recently, I have been doing work on PSV datasheet that have to be filled up by "Allowable over pressure (%)" and "Over pressure Factor" . But it gets me really confusing to differentiate between these two parameters. As far as I know, these two parameters are quite same!

If someone could enlighten me about this I would be very grateful.

Many Thanks,

[fallah]

Recently, I have been doing work on PSV datasheet that have to be filled up by "Allowable over pressure (%)" and "Over pressure Factor" . But it gets me really confusing to differentiate between these two parameters. As far as I know, these two parameters are quite same!

If someone could enlighten me about this I would be very grateful.
 

 

Hi,

 

They could be different...

 

Overpressure factor is the factor of the pressure exceeding over the design pressure...

 

Allowable overpressure is the percent of the pressure over the design pressure to reach the 1.1 times of MAWP (1.21 for fire case)...

 

For example if design pressure is 90 barg and MAWP is 100 barg, then the normal overpressure factor can be 10% over the design pressure to reach 99 barg (still lower than MAWP) and at the same time allowable over pressure would be around 22.2% ((20/90)*100)...

[latexman]

I think the confusion comes from not strictly adhering to the definitions of the applicable Code.  I suspect the datasheet writer confused "overpressure" with "accumulation" in one place and adding the extraneous word "factor" in another.  I recommend re-reading the instructions or procedure that accompanies the datasheet, and having a discussion with the datasheet  author.

Edited by latexman, 03 December 2016 - 08:25 AM.

[shahidulislam48]

Dear Fallah, thank you for your solution and helping me to understand the facts clearly.

 

And also thanks to "Latexman" for figuring out the main problem for us.

 

If I don't get misinterpretation, in Fallah's statement, Design Pressure = Set Pressure, and it could be possible that Design Pressure = Set Pressure = MAWP. Then,

 

Relieving Pressure = Set Pressure + Allowable Over Pressure + Atmospheric Pressure

 

I would be grateful to know about the Required Capacity in Barg as I'm wondering that capacity in pressure unit!!. If it is ok then pressure will be the relieving pressure.

 

If I'm wrong please help me.

 

Regards

shahidulislam48

[fallah]

Hi,

PSV required capacity should be in kg/hr or m3/hr units. Then the pressure units can not be applied to PSV capacity.

[shahidulislam48]

Dear Fallah, could you please look at the attached file of datasheet portion?

 

What does the marked one really mean?

 

 

Attached Files

•  Datasheet.jpg   137.63KB   1 downloads
•  Datasheet.jpg   137.63KB   0 downloads

[fallah]

Hi,

At first please specify what does the "DEDT" in data sheets stand for?

[shahidulislam48]

Hi,

At first please specify what does the "DEDT" in data sheets stand for?

 

DETD = Detail Engineer to Determine

 

I am doing detail engineering.