Hose water pressure

[raf_gti]

How much does the water pressure diminish through a standard tap/hose? I currently have a 15m hoseattached to my power washer which is perfectly fine. Unfortunately to be able to use it at my garage I will have to run at least 30m of hose to it, will the pressure drop to a ridiculous amount over this length?

ta!

[Road2Ruin]

No - you will only notice a pressure drop if you are inscreasing the height from the outlet.

[Simpo Two]

Something has to give because of friction, so it must be flow rate?

[HiRich]

There will be a small but noticeable drop, if you want a decent flow rate (e.g. an open pipe rather than a trigger nozzle). If you've got an impressive head at 15m, it will be OK @30m, but noticeably less impressive.

[Simpo Two]

Move the powerwasher to the garage?

If there's no power then electricity will cross the 30m gap better than water I suspect.

[Road2Ruin]

Simpo Two said:

Something has to give because of friction, so it must be flow rate?

Friction will be negligble. I had a 40m hose at home for years and never noticed any pressure issues. I agree that there will have to be some pressure drop but I dont think it will make any difference to the OP.

[King Herald]

Road2Ruin said:

No - you will only notice a pressure drop if you are inscreasing the height from the outlet.

Output pressure might be the same, when the water is static, but flow will drop the longer the hose gets once water starts flowing.

[jeff m]

Flow or supply is your concern not pressure.
If you want to check that your hose will not supply sufficient water and could cause cavitation in your pump, get a five gallon bucket and measure the time it takes to fill. (Get galls/minute)

Do the same using your power washer at your best supply point. You will find that an electric power washer will use a lot less galls/min than a house supply. I doubt your electric power washer is 2 galls/min.
Should not be a problem, but you check if you want to

Apols in advance if your hose only delivers litres

Edited by jeff m on Wednesday 20th January 15:27

[Ledaig]

If you want to know the losses on the hose length, you will need to find out the hose friction coefficient and a few other bits of info.....

The method is as follows:

a = (y(l/d))+z

Where:
a = Loss index of fluid system
y = Hose friction coefficient
l - Hose length
d = Hose diameter
z = sum of the loss index of individual components used in the system (excluding the pressure washer!)

To follow this and calculate pressure losses:

P = a x (p/2) x v^2

Where:

P = Pipe loss
a = Loss index of fluid system (as above)
p = Initial system pressure
v = Mean velocity of the fluid

[raf_gti]

Ledaig said:

If you want to know the losses on the hose length, you will need to find out the hose friction coefficient and a few other bits of info.....

The method is as follows:

a = (y(l/d))+z

Where:
a = Loss index of fluid system
y = Hose friction coefficient
l - Hose length
d = Hose diameter
z = sum of the loss index of individual components used in the system (excluding the pressure washer!)

To follow this and calculate pressure losses:

P = a x (p/2) x v^2

Where:

P = Pipe loss
a = Loss index of fluid system (as above)
p = Initial system pressure
v = Mean velocity of the fluid

Thanks for that

In the end I bought an extension from B&Q for £15, if it doesn't work then no big deal.

The reason I can't just move the pressure washer to the garage is that the tap is outside the back wall, 30m or so away from the garage.

[Ledaig]

Just put a tank in the garage (up as high as you can) and run the pressure washer from that with the hose refilling it. If you run out of water just stop for a few mins.