Message Board - Irrigation: Water Pressure Low
11 Jul 2011 by Scott Manning
Hello i have recently purchased a 100m 1/2" hose and a sprinkler, the water pressure isnt high enough for the sprinkler to work correctly has anyone got any advice how i can get more pressure into it, the hose connects directly to the outside tap.
11 Jul 2011 by Aladdin
As far as I'm aware the only way is to acquire a suitable capacity tank and a pump capable of supplying the appropriate pressure at the sprinkler.
e.g I believe it's 4 bar (whatever that is in p.s.i.) for the Rollcart Travelling Sprinkler.
From the posh end of the room!!
12 Jul 2011 by chrismitchell
100 metres of 1/2" hose has a huge frictional loss. If the water pressure at the tap is enough to operate the sprinkler a larger bore hose will solve the problem. Idealy 1". If not, as Alladin says, a tank and a pump is your answer. Karcher do a really good pump for about £80. I use one to irrigate my garden. It gives both good pressure and a very good flow.
Chris
You will never see a statue in honour of a committee.
12 Jul 2011 by tonybolton
Chris might just be me but I don't understand how by using a larger diameter hose the pressure will increase surely it will decrease, if not we'd all be irrigating through 4" drain pipes.
A Freudian slip is when you say one thing but mean your mother
12 Jul 2011 by Bjarni Hannesson
@Tony
The pressure will not increase, it just won't drop as much. As water travels through a pipe, portion of it is in contact with the walls of the pipe causing friction. Friction leads to pressure loss.
The smaller the diameter, proportionally larger quantity of the water is in contact with the walls of the pipe. This leads to more pressure loss in smaller pipes compared to larger ones.
1/2" pipes cause quite some pressure loss over a run of 100 m. You can calculate this by using the Hazen & Williams equation (just google it).
With this equation, you can calculate the diameter of the hose you need to run you sprinkler without purchasing a pump (given the source pressure is enough to run it in the first place).
The reason why you don't buy a 4" pipe is because that might simply be far more than you need. You are better off buying a smaller pipe and spend the rest of the money on a few pints :)
Regards
Bjarni
13 Jul 2011 by chrismitchell
Very well put Bjarni, you saved me explaining it!
Chris
You will never see a statue in honour of a committee.
Back to Top - Go to Next Unread Message
This Message is closed, you may not post a reply at this time
