Non return valve

[Omnimill]

I'm wondering if I could make something similar to this using a 5 or 6mm stainless steel ball in a conical (countersunk) seat. What do you reckon, would it work as well?

http://www.aquaessentials.co.uk/tmc-aquagro-co2-glass-non-return-valve-2916-p-4386.html

I'd use a glass tube epoxied into stainless end caps.

Vic.

 

[picclock]

I've made several that way and they are very effective.

The key is how good do you want the reverse seal to be ? best is with an oring fixed to the seat/inlet. Brilliant seal. Adequate seal with plastics as the seating material, or you can even get a reasonable seal using an aluminium seat made with just a drill (suspect ball nose mill may improve).

The orientation of the valve is quite important as gravity can be used to ensure the ball is in the correct (sealed) position if the source is pumped.

I have also made a version whereby the valve closes when the flow rate exceeds a nominal value. This was for a sight gauge in the event that the glass failed. The valve is placed horizontally such that the ball is against the bottom of the housing, with a small gap over the top to allow the fluid into the gauge. If the flow becomes large the decrease in pressure above the ball caused by the accelerated flow lifts it allowing it to seal the outlet.

Hope this helps

Best Regards

picclock

 

[Ken I]

I'm wondering if I could make something similar to this using a 5 or 6mm stainless steel ball in a conical (countersunk) seat.

It works well but a countersink surface generally isn't good enough for a great seal - one cure is to take a hardened steel ball and whack it into the the seat with a pin punch and hammer - creating a small well finished sealing annulus.

Ken

 

[Omnimill]

Thanks guys. Do you really think a seat made with a bull nosed cutter would be better then - I do have a few bull nose cutters and probably have a suitable size.

 

[Blogwitch]

When I make any kind of sealing face, whether it be for a tapered needle or a ball, I always use a flat bottomed sealing face, giving a very narrow sealing edge to the hole.

Like Ken, if it is to take a ball, a slight tap of the ball onto it's seat makes a perfect seal, but don't use the ball afterwards, put a new one in there.

You can buy Viton and other plastic/rubber balls that work very well indeed at sealing, but they will only last a season at most before they require changing.

John