Pressure in a Parallel Pipe System

Hi mikexp

If the 2 pipes deliver to a common destination the pressure loss in the 2 pipes will be equal.

Go to http:\\www.gwis.co.za and download a demo version. You can then play around with pipe sizes etc.

Hi Hendrik,

Thanks for the response, I already knew that in the parallel pipe system with same destination, the pressure drop will be the same, however I still not sure about the pressure characteristic in each branch pipe,

let's say consider that there are no pressure drop, the pressure source is P1 which is in main pipe, so could be bellow relation is true? :

P1. V1 = P2. V2 = P3.V3 or P1.V1 = P2.V2 + P3.V3

where P2 & P3 are the pressure of branch pipe from main pipe.

Which one is rite? the 1st statement or the 2nd statement?

(D1 (diameter main pipe) not equal with D2, D2 not equal with D3)

is it not already discussed in

http://cr4.globalspec.com/thread/3407

where you too have participated ?

Hi all,

The pressure drop accross the two parralell pipes will not be exactly the same - take your pipe friction factor into account. :) It will be close - but not exactly the same.

Have a look at Bernoulli and the ANSI/ISA-75.01.01-2002 (IEC60534-2-1) standards for valve sizing.

You should bear in mind that no two pipes are exactly the same.

Now that we have covered the semantics - for all design intents and purposes - yes the delta P would be the same if as stated above they flow into the same process stream.

Would you ever end up with a situation where P1 < P2 < P3 - this will depend on your process medium. Perhaps you might have uneven scaling (someting similar perhaps) on one line and this line might start chocking/blocking up. This will give you the situation where the pressures are different.

If you look at the pipe friction factor P1<>P2<>P3 all the time. :)

Regards,

Craig