Nitrile ball pushed past its seat

[nigel jones 5Participant @nigeljones5]

I have used nitrile balls in clacks for some time now with great success. I have read that they can deform and end up being forced past their seat, thus blocking the clack. Today I investigated an axle feed pump which had stopped pumping and to my suprise found the ball pushed past its seat and into the pipe below. When I eventually got it out it was propper egg shaped! Ball was correct size for seat, in terme os if i had used a steel ball, so maybe one size up next time.

[nigel jones 5Participant @nigeljones5]

[Boiler BriParticipant @boilerbri]

That's interesting. I have stainless steel ones in mine, I have tapped them down onto the seat but they still dribble a bit. I might try some of them and may end up with a better seating.

Bri

[Chris GunnParticipant @chrisgunn36534]

Fizzy, I remember reading somewhere "If using nitrile balls go one size bigger than you would for a steel ball", so your reaction was probably correct.

Chris Gunn

[nigel jones 5Participant @nigeljones5]

you had to see it to believe it !!

[Ian S CParticipant @iansc]

Bri, If you use Stainless balls, don't use the ball that you hammered onto the seat, it will be distorted, and will leak, use a new ball on the valve.

Ian S C

[nigel jones 5Participant @nigeljones5]

im sure they are more forgiving and provide a better seal, just be sure to get them one size bigger – and dont hit them with a hammer

[Boiler BriParticipant @boilerbri]

Cheers. For that Ian. I will note it

Bri

[cParticipant @c]

Nitrile balls should sit on a 90 deg. conical seat with an outlet bore diameter of not more than 60% of that of the ball.

[norm nortonParticipant @normnorton75434]

Posted by fizzy on 18/04/2016 19:29:29:

found the ball pushed past its seat and into the pipe below.

This infers it is the inlet at the bottom? If the outlet blocks then an axle pump can potentially develop several thousand psi and it will drive a nitrile, or any deformable, ball straight through the inlet ball seat. I also have found one driven inside a copper pipe.

No amount of seat redesign will prevent it happening. The question is how did the outlet became blocked enough to generate the pressure? I would suspect the clack into the boiler.

I have learnt my lesson and use only metal balls in a hydraulic pump. I does not matter if they weep a little bit. It is the clacks into the boiler that need to seal perfectly and here the nitrile balls are most useful, as long as the valve is designed to keep the ball well away from the outlet.

Norm.

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