Using nitrile balls in clack valves

Hi all, novice here.

Just found this thread. I am trying to repair a leaky old clack valve. It's a phosphor bronze one fitted directly to the boiler. Took apart to clean in some acid and found the ball was a nitrile one with a nice indent all around it, presumably where it was being worn all these years.

I have an urge to replace with a metal equivalent (or at least try to)- my question is whether I should try a stainless steel ball or a bronze ball as a replacement- would it matter or make much difference?

If I did use steel, would this react with the bronze fitting? The reaction charts are a little confusing for a begginner!

Thanks!

Ed

Three advantages of Nitrile:

• the ball wears out rather than the valve seat.
• the material squishes slightly into the bed and makes a better seal than a metal ball, especially if the valve seat is a bit manky
• there's no risk of electrolytic corrosion damaging the seat

Replacing a nitrile ball with metal increases the chance of a weeping leak in the short term, and maybe much worse trouble later due to physical and corrosion damage.

I'd replace the ball with new Nitrile. The designer probably selected Nitrile rather than metal for sensible reasons. All design is a compromise. In this example the ball doesn't last forever and has to be replaced, but that's less painful than having to replace the whole valve.

Dave

That all sounds very sensible! I'll probably pop in a fresh nitrile one then. Thanks!

My fellow club members have mixed views on the use of nitrile ball in clacks as they have been know to get pushed into the boiler that said I have used nitrile ball in my injector clack as I need to make a new one I ran my 3" Burrell all last year with a nitrile ball and replaced it with a new one this year. I may get shot down by I'd used SS or PB balls unless you have a problem with them seating

H

Stainless balls are absolutely fine in bronze clack valves and they last indefinitely.

Edited By Redsetter on 20/05/2023 19:09:57

One thing that can be done with a metal ball that Nitrile can't do, is to whack one with a hammer into the seat so it deforms to fit the ball accurately. Replace the whacked ball with a new one because it probably squished out of shape and is no longer a sphere.

Beware - I've never tried it!

Dave

Edited By SillyOldDuffer on 20/05/2023 19:18:24

Many years ago I worked with high pressure airless paint spray units, 2500psi. These used a small check valve, the ball material depended on the paint intended to be used, either carbide or stainless steel. We used to put a steel ball in and strike it into the seat to create a perfect seal then build the check valve with a new ball. Some of our other pumps used glass balls in the check valves but these were 1/2” in diameter. Once seated properly the check valves rarely gave any trouble.

I have been using ceramic balls in the check valves in the water pump (bronze housing, shaft driven) of my traction engine for the past 5 years with no problem. (The boiler clacks use winged, taper type).