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# Velocity comparison 45° T vs 90° T.

#1
07-10-19, 01:38 PM
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Join Date: Jul 2019
Posts: 3
Velocity comparison 45° T vs 90° T.

Repair job due to freeze failure. Existing: coming off of a 1-1/4" Main to a 90° T WITH 1/2" line to spigot. How much velocity would increase by replacing the 90 with a 45° T in line? (Trying to give my pressure washer as much volume as possible).

option B: come off of the main with a 3/4 in 45° T & running 3/4" all the way to the 1/2" spigot?

Last edited by ax2n38; 07-10-19 at 01:39 PM. Reason: Newbe problem.
#2
07-10-19, 03:35 PM
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Join Date: Sep 2016
Location: USA MI
Posts: 9,265
velocity would increase
The measurement would be volume due to less resistance not velocity!

And yes, the straighter the run, with less bends the less resistance and the more volume!

Running 3/4 again would have less resistance than 1/2 so more volume but the restriction to 1/2 again is significant!

#3
07-10-19, 03:52 PM
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Join Date: Jul 2019
Posts: 3
1/2 vs 3/4 from the main.

Thanks!, From the main does it help to run the 3/4 to the spickot opposed to taking the 1/2 right from the main?

It's hard to find 45° Ts, especially a 1-1/4 x 1-1/4 x 1/2.

#4
07-10-19, 04:01 PM
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Unless you have a massive pressure washer ...... a standard 1/2" line should be able to deliver you maximum pressure. You're only talking gallons per minute.

#5
07-11-19, 11:57 AM
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Join Date: Jul 2019
Posts: 3
Pressure washer

Pressure washer runs at 4 gallons a minute.. I think I crank my well up to 60 PSI while I'm running it but I think I read that's not good for the house system. The half-inch has been able to keep up with it in the past even with that 90-degree half inch T but I'm pretty sure it's borderline.

I don't think I have to worry about hurting the well pump cranking the pressure up but have to worry about hurting the house Plumbing so this time I plan to shut the house off. Thanks again it really helps to have insight!

#6
07-11-19, 03:57 PM
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Join Date: Sep 2016
Location: USA MI
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a standard 1/2" line should be able to deliver you maximum pressure
Just trying to be consistent, the statement should be "maximum volume"!

#7
07-12-19, 04:40 AM
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Just run 3/4" to your sillcock. A 3/4" T will have higher flow volume and be much easier to find than the 45 degree fitting.

#8
07-12-19, 10:34 AM
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While a 90 deg fitting does cause more resistance than a 45, and longer bends are better as well (two 45's rather than one 90)... outside a lab environment, you'd never notice the difference.

You'd be better to look at the spigot you're using as ball type valves will give you much more flow than globe valves.

If my memory serves, a 1/2" pipe should supply around 7 GPM without a problem assuming typical water pressure. So you're definitely over-engineering the solution