Way to work out flow rates

[southcoastboile]

does anyone have a chart or know an equation to work out how pressure will improve over the length of the pipe.

We have installed an unvented cylinder in a loft and have 14lpm with water softner connected. 18lpm without. 2.2bar pressure at shower upstairs.

Customer wants more pressure as they have 25lpm at tap downstairs. 4.5bar pressure. Confirmed by water board apparently.

The main runs up to the cupboard in 15mm so we are looking to find out what the lpm gain would be if we were to upgrade the 15mm pipe to 22mm.

I wondered if anyone had a sum to work it out. I.e every mtre in height of 22mm pipe will reduce the flow rate from at the tap by 0.5lpm or something like that?

Many thanks in advance!

 

[Last Plumber]

Thanks rik. That's what I meant sorry. Just like standing and working pressure at a meter.

Thanks for reply last plumber. So let's say we know the dynamic pressure at the stopcock and before the pressure reducing valve. What calculation would you then use to work out what you would potentially gain by upgrading the pipe?
Its okay knowing pressures prior to the cylinder pressure red valve and at the stopcock but they won't be the same due to the height the water is traveling and the restrictions in the pipe work. I.e bends and sockets.
I would assume that pressure at stopcock and flow rate would be all that was needed to work out what pressure you would achieve the other end of the pipe.

For example 25lpm and 4 bar at stopcock would reduce pressure by 0.2lpm for every mtre of horizontal pipe. 0.4 every meter of vertical. 0.2 for every bend, 0.1 for every socket.

Surely someone must have come up with a simple equation like that?

If you have 25 lpm and 4 bar at the main stop tap and you pipe the Cylinder in 22 mm tube it will sort it, yes. I think @ShaunCorbs said that earlier on in the thread.

As far as equations go, yes there are equations for water pipe sizing just like there are for just about anything you want to work with.

@steadyon posted a link to some of them.

Have you looked at those?

 

[SimonG]

What does the pressure reducing set take it down to?

 

[Last Plumber]

What does the pressure reducing set take it down to?

Must be 2.2 Bar. If he is testing the Shower?!