10 replies to this topic

[Low]

Hi,

I would like to know how should I make a educated guess about whether my water flow rate at the outlet is sufficient.

Fluid: PCW
Temp: 12-15C
Pressure: 5 bar
flowrate in the main header, 16" = 300-400 m3/h

Final outlet pressure: 4 bar
Required flowrate: 1 m3/h

We are going to hot tap a 6" pipe and I am tasked to find out if a 1 1/2" hot tap would suffice. At the moment the plan is to tee off each 1 1/2" pipe to supply for 2 units, meaning each hot tap will be supplying two units.

From 1 1/2" the pipe will be reduced to 1/2", passing through a ball valve, and then finally the outlet would be 3/8". The required final flowrate for the 3/8" outlet is 1 m3/h, and the outlet pressure is about 4 bar.

From the mainline flowrate it would seem like enough but I would just like to make sure.

Just to add, everything is existing and the only part we are adding would be from the 1 1/2" pipe onwards.

So to conclude, I would like to know if my flowrate obtained from the 1 1/2" pipe is sufficient, or do we need a bigger pipe, and how did you come about getting the figure.

Appreciate the help.

[Low]

Also how do you calculate the flowrate in an equal tee? Divide the flowrate evenly? And for a reducing tee you divide it using the ratio of their radius? Because if I use this method I barely have enough water for less than a quarter of the plant, so something must be wrong with my calculations/assumptions.

[vikramltv]

It will be better if you attach a scketch for you sceme elaborating your problem..

[Low]

Will do.

[breizh]

You can dowload from Internet a software called PSIM ( pump system improvement modeling tool ) which can support your query . As stated , you must define your sketch first.
Hope this helps

Breizh

[Low]

Sketch attached. Appreciate the help.

Attached Files

•  sketch.xlsx   14.36KB   75 downloads

[Low]

Anyone know how to use the PSIM?

EDIT: I can't really define my sketch in the PSIM because it only allows 12 pipes and 24 junctions, and both upstream and downstream of each junction have to be defined. I don't think it's enough for me, unless I am doing this the wrong way. Forgive me, I have no prior experience with piping software.

Edited by Low, 17 February 2012 - 01:26 AM.

[breizh]

let you use the examples and manipulate the input data and run the program , you should understand (From simple to complicated ones).
For each pipe you need to provide diameter , rugosity , altimetrie .

It's really home work .

Breizh

[vikramltv]

I have not used PSIM, But I had solved the similar problem with PIPENET that requires flow or pressure inputs at end points. It will size your line in design mode once you give the fitting , elevations and end point pressure/flow. get a copy of it and it will surely do wt you need..

[Low]

Hi guys thanks for the valuable input.

[S.AHMAD]

1. We need to know the piping configuration - pipe length, fittings, elevation etc
2. Use line pressure drop equation to determine the flow rate