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Post by tomtomgo on May 28, 2023 16:47:08 GMT
Hi,
I have a commercial 5/16" boiler type clack valve with a 'C' stamp on top of it that has leaked since purchased but it has been years now so I can't claim under warranty.
It's clean, tested on air not connected to anything other than an airline and it still leaks.
There are plenty of threads preaching the usual to resolve but I just want a valve that works so on club day it doesn't ruin a nice day out.
Is buying new the only answer until the angels of QA smile on me or is there a dummies guide to a reliable clack valve that only the inner circle of ME groups are allowed entry?
Tom
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millman
Part of the e-furniture
Posts: 297 
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Post by millman on May 28, 2023 18:02:44 GMT
You have two choices, re-cut the seating and re-seat the ball on the commercial one or make your own from scratch, I prefer to make all my own boiler fittings including injectors to the design in DAG Browns excellent book, that way you have total quality control and if they do fail only yourself to blame. The quality standards of commercial fittings has plummeted in recent years, I have seen fittings purchased by fellow club members that are still full of swarf, I wonder where the trade are sourcing them from.
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firebird
Seasoned Member
Conway now up and running
Posts: 149
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Post by firebird on May 28, 2023 18:18:23 GMT
Hi Tom I use these. Cured all my woes   Cheers Rich |
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Post by tomtomgo on May 29, 2023 8:10:50 GMT
Thanks Rich, I have ordered various sizes so I will give them a go and report back (shipping will take a while).
I agree regarding deteriorating quality over the years and have also had to clean most components due to dirt or swarf from new.
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Post by tomtomgo on May 29, 2023 8:15:37 GMT
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Post by steamjohn248advent on May 29, 2023 10:05:53 GMT
I have previously written to recommend 'bobbin' type check valves. All the locos on the Land B (min) R at the Museum of Power are fitted with this type of valve. they never leak never stick are as has been said before, bomb proof (and easy to make). also fitted to our 26' Coal fired Steam Launch. Contact me if you need a drawing although there is one on this site if you can find it.
Steamjohn
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Post by simon6200 on May 29, 2023 10:48:12 GMT
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firebird
Seasoned Member
Conway now up and running
Posts: 149
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Post by firebird on May 29, 2023 19:52:22 GMT
Hi
I bought some silicon nitride balls for my Gordon smith safety valves (see my topic)
They seem pretty good but I haven't tried them under steam as yet
Cheers
Rich
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Post by chris vine on May 29, 2023 23:01:30 GMT
Hi All,
Some experience with leaking clack valves:
I made the clacks for my loco, Bongo, with conical seats to accept Viton (rubber) balls.
These were absolutely perfect and totally leak free - until the boiler cooled down after a steam-up. Then, as the steam condensed and created a partial vacuum in the boiler, the balls would be lifted off their seats and then they would drop back in a slightly different orientation. Because they had been hot and pressed into the conical seats, they were slightly egg shaped and the contents of the boiler would then drip on the floor!
I made little bungs for the injector overflows to stop this.
Then our friend, Roger, of this parish, came up with the high tech solution of using silicon nitride balls. These are super hard and very very round.
I got some and then did Roger's trick of pressing them into the seat to form a matching surface. This took a lot of force because the clack bodies were made of phosphor bronze, PB102, and the seats being conical had a much larger area in contact with the balls than would usually be the case with a sharp cornered hole.
Nevertheless, I managed to get them to seat perfectly and was very happy - until one steaming, I could not stop one of them leaking for around 30 minutes. Then, just as suddenly the leak cured itself. Very strange.
Then perfect for a while and then, another day another leak.
After a while, I decided that the leaks must be caused by very tiny bits of dirt (despite filtered water in the tender) getting between ball and wall of cone. Again, this may not be a very good shape compared to a sharpish hole as there is a lot of area to trap a bit of dirt and the pressure on the much larger area to squash the dirt is much less.
Back to the drawing board.
Then I reckoned that I needed something with a hardness somewhere between Viton and Silicon Nitride. I came up with the exact same solution as Rich, Firebird. PTFE Balls, for pumps, also sourced from Ebay.
Finally, they seem to provide a perfect seal - until.....
All best
Chris.
PS, I realise that the conical seat is a bit of a special case. I am pretty sure that the Silicon Nitride balls would work well on a hole type of seating.
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Post by Boadicea on May 30, 2023 8:15:14 GMT
Can I suggest giving up the balls and thinking more about O rings?
There have been several good designs on this forum - some which are simply ball replacements.
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Post by andyhigham on May 30, 2023 9:03:35 GMT
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Post by tomtomgo on May 30, 2023 9:38:22 GMT
If the PTFE balls don't work for me I will give these a go, thank you! |
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Tony K
Elder Statesman
Posts: 1,573
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Post by Tony K on Jun 1, 2023 9:50:10 GMT
Can I suggest giving up the balls and thinking more about O rings? There have been several good designs on this forum - some which are simply ball replacements. Can't be doing with balls - what Baggo did - works for me and no problem with anything ....  |
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Post by tomtomgo on Jun 1, 2023 10:56:52 GMT
Can I suggest giving up the balls and thinking more about O rings? There have been several good designs on this forum - some which are simply ball replacements. Can't be doing with balls - what Baggo did - works for me and no problem with anything .... If you or someone could please provide links to these plans that would be helpful, thanks. Tom |
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Post by tomtomgo on Jun 9, 2023 14:57:05 GMT
Unfortunately, the PTFE balls didn't work for me (maybe the valve body itself is flawed) but the quality of the balls (stop laughing) are brilliant so I would say they are better to use than SS.
I have gone ahead and purchased the clacks Andy mentioned (thank you) that have a valve element with an O ring seal to see how they are made and if they are more reliable.
I will report back once fitted and tested.
Tom
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