maximum differential pressure

[Mitesh87]

hello to all,

AS per API 610 ,

Max disch.pr = max suc pr. + max differential pres.

in datasheet process ppl give suct pre normal & max. so i get max suc pr. but how can i find max diffe presssure ?

i m new here and new in design so please forgive me if this que is silly..

 

[LittleInch]

Mitesh87.

Before I address your question, if you're going to be coming here again to ask a question, write this like you would write an e-mail or report to your superiors, i.e. use proper english, not txt lang and provide details or an example with real numbers.

Two things - When doing anything with pumps, work in head. Pressure to head is quite easy, but then the units don't get confused.

Maximum differential head comes from the pump vendor pump curve for what ever pump you want or can be inserted into a data sheet if it is critical. This figure will be at zero flow, but is also often when the suction pressure (not suc pre!) is at its highest also. You then convert this differential head figure into pressure using the density of the fluid you're pumping

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

 

[Mitesh87]

LittleInch,

Thank you very much for valuable reply.

I will keep in mind your instructions while asking for the same.

As I mentioned that I am New here and all..

But its ok...

Hope to see you again for more queries.

BR,
Mitesh.

 

[GPRnD]

The pump vendor will confirm he maximum differential head (or shutoff head)

Max differential pressure = rho x g x h where

rho = the fluid density in kg/m3
g = the gravitational constant - normally 9.81 m/s2
h = the maximum differential head supplied to you by the pump supplier

The answer with the above units will be in N/m2 or Pa. Divide it by 100000 to get Bar


One other comment, you are probably aware of this but the maximum discharge pressure of the pump is not equal to the MAWP.

The MAWP per API 610 = max suc pr. + 1.1 x max differential pres.

 

[Mitesh87]

Thank you GPRnD,

As u stated that ,

The MAWP per API 610 = max suc pr. + 1.1 x max differential pres.

i refered API 10th and 11th editions ,

it shows - MAWP shall be at least the maximum discharge pressure plus 10% of the maximum differential pressure.

So, if my max differential pressure is 100 so 10% of 100 = 10/100 * 100 = 10 and

As u said 1.1 * max differential pressure = 1.1*100 = 110.

can you please correct if i am wrong?

 

[GPRnD]

You end up with the same answer either way. I just expressed it differently.

Try a worked example:

Suction pressure = 1.5 barg
Pump differential head at shutoff = 120m (maximum differential head)
Density = 1000 kg/m3
g =9.81 m/s2

Maximum differential pressure = 120 x 1000 x 9.81 / 100000 = 11.8 barg

Maximum pump discharge pressure = 1.5 + 11.8 = 13.3 barg

MAWP by your method = 13.3 + 0.1 x 11.8 = 14.5 barg

MAWP by my method = 1.5 + 1.1 x 11.8 = 14.5 barg

 

[1gibson]

Don't forget to consider this at the maximum specific gravity.