A quickie question

[silverfox]

When building a handpump what is the ideal 'lift' on the outlet size fro a 7/32d ball

Thanks

[RGR 60130]

Sept 27, 2021 23:02:43 GMT silverfox said:

When building a handpump what is the ideal 'lift' on the outlet size fro a 7/32d ball

Thanks

Ron,

The ideal theoretical lift is a quarter of the seat diameter. If, for example, your 7/32" ball sits on a 3/16" diameter seat, the ideal theoretical lift would be 3/64". In practice I'd add a few thou to that.

Reg

[ettingtonliam]

I asked the same question myself a few weeks ago. Reg replied as above, 1/4 of seat diameter, another reply said 1/3rd of ball diameter, one drawing I have says 3/32" lift max for 7/32" ball, another says 1/32" lift for a 1/4" ball.

I've gone for 1/16" lift for a 1/4" ball and 3/16" seat, and will use the same figure on the pump I'm just starting which has 7/32" balls on 3/16" seats.

[dfh]

Sept 27, 2021 23:02:43 GMT silverfox said:

When building a handpump what is the ideal 'lift' on the outlet size fro a 7/32d ball

Thanks

If you have a look at the site in the link below it gives useful information on ball size, orifice size and lift calculation.
David

ibls.org/mediawiki/index.php?title=Design,_Care_and_Feeding_of_Check_Valves

[silverfox]

Gents
Thanks.

Would i be right in saying the same applies on the inlet side?

Mr Evans late of this parish, does not show anything on the pump for the B1, hence i asked the experts

[RGR 60130]

Sept 28, 2021 8:11:05 GMT silverfox said:

Gents
Thanks.

Would i be right in saying the same applies on the inlet side?

Mr Evans late of this parish, does not show anything on the pump for the B1, hence i asked the experts

Yes, inlets and outlets are both similar.

Reg

[John Baguley]

I remember reading an article in Model Engineer (or perhaps EIM?) some years ago about the lift required for balls in handpumps etc. I can't remember the details now but the author had carried out various tests and concluded that the ball lift required for satisfactory operation was much less than the oft quoted figures. It was certainly much less than D/4, more like D/10. I'll have to try and find it again.

John

[RGR 60130]

For theoretical full flow, the outlet area must equal the inlet area.

The inlet area is calculated by πD² / 4

The outlet area is the circumference of the inlet (seat) x the lift L of the valve (ball), calculated by πDL

Dividing the inlet area by πD therefore gives the lift L.

Considering Ron’s scenario with a seat diameter of 3/16”.

Inlet area = (π x 0.1875 x 0.1875) /4 = 0.02761 square inches

The Circumference of the seat is π x 0.1875 = 0.5890 inches

The required theoretical lift is therefore 0.02761 / 0.5890 = 0.04688” (3/64”)


The whole thing will get messed up if you don't have the same area around the ball for the water to get past it.

Reg

[ettingtonliam]

Sept 28, 2021 7:51:34 GMT dfh said:

Sept 27, 2021 23:02:43 GMT silverfox said:

When building a handpump what is the ideal 'lift' on the outlet size fro a 7/32d ball

Thanks

If you have a look at the site in the link below it gives useful information on ball size, orifice size and lift calculation.
David

ibls.org/mediawiki/index.php?title=Design,_Care_and_Feeding_of_Check_Valves

When I click on the link its says 'currently there is no text on this page'!

[jo479]

Forgive my ignorance, what is "n"?

[don9f]

I think Reg means the mathematical constant “pi” (zoom in and its not actually “n”)?...for which I can’t find the proper symbol on my ipad !

Cheers Don

[RGR 60130]

Sept 28, 2021 17:29:05 GMT don9f said:

I think Reg means the mathematical constant “pi” (zoom in and its not actually “n”)?...for which I can’t find the proper symbol on my ipad !

Cheers Don

Yes, it's Pi.

[jo479]

Should have realised that, thanks.