How to estimate hand-powered feed pump output pressure

How to estimate hand-powered feed pump output pressure

This topic has 5 replies, 3 voices, and was last updated 31 January 2017 at 16:51 by PaulR.

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31 January 2017 at 14:00 #281479
PaulR
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@paulr
I'm just finishing off a simple feed pump and although I won't be using it to fill a boiler I'd like to get an idea of what pressure it will work against.

I don't have a pressure gauge to stick on it so can anyone suggest an empirical way of estimating this figure? I doubt my maths is up to calculating it properly even if someone would care to explain it!

Paul
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31 January 2017 at 14:00 #25054
PaulR
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@paulr
31 January 2017 at 15:21 #281499
Neil Wyatt
Moderator
@neilwyatt
If the piston is operated by a lever pivoted in the middle:

pressure in PSI = (pounds you pull on lever * pivot to pulling point on lever distance) / (area of pump ram in square inches * pivot to ram distance)

If you use kilograms and square millimetres, divide by 100 to get an answer in Bars

These aren't exact answers but will get you pretty close.

Neil
31 January 2017 at 15:32 #281506
PaulR
Participant
@paulr
Thanks Neil, but it's a simple plunger arrangement, a bit like a bicycle pump, rather than lever operated, so 'pivot to pulling point on lever distance' is zero… so I guess I'd use '1' in your formula as there's no leverage. What would I do about 'pivot to ram distance'. It's been a very long time since I studied levers and pulleys etc at school!
31 January 2017 at 16:16 #281528
JasonB
Moderator
@jasonb
Also treat it as 1. so if you put 1lbs weight onto your plunger and say the piston had an area of 1/4sq in then you would get 4psi pressure ( 1/0.25=4), if area of your piston were 1/2 sq inch then you would only get 2 psi (1/0.5 = 2)for the same 1lbs applied force.

Edit or if you don't like the maths there are several calculators online such as this

Edited By JasonB on 31/01/2017 16:21:50
31 January 2017 at 16:51 #281540
PaulR
Participant
@paulr
Posted by JasonB on 31/01/2017 16:16:13:

Edit or if you don't like the maths there are several calculators online such as this

Cheers Jason, for some reason I thought it would be more complicated!
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