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Post by Balljoint on Jan 22, 2015 10:19:21 GMT
Hi
I have just made some new clack valves to the design in EIM, and cannott get them to seal perfectly.
Is there a knack to this or am I expecting to much, and they will always leak slightly.
Regards
Colin
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Post by Deleted on Jan 22, 2015 13:44:28 GMT
Hi Colin------- no, they shouldn't leak at all..It's always a good idea to re-locate any clacks that are fitted into the lower part of the backhead ( because of all the crud that gathers there over time ) and have them somewhere along the centre-line of the barell such that they discharge into the steam space............I'm not conversant with the EIM design as such, but would advise you to pay close attention to the seat and the fit of the ball into it.....Some folk have fitted a small O-ring to improve sealing....Traditionally a sharp tap with a drift onto the ball tends to help.....If you are really patient try soldering a used ball onto the end of a small Brass rod and lapping the seat with fine grinding paste......... It might be worth knocking-up an Hydraulic test rig rather than have to raise steam every 5 mins.....
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Post by Balljoint on Jan 23, 2015 10:08:31 GMT
Thanks for the reply, I shall have to try harder to get a perfect seal
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pault
Elder Statesman
Posts: 1,500
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Post by pault on Jan 23, 2015 10:57:28 GMT
All that Alan has written is good advice, in addition don't use the ball that you used to form the seat as the ball that you are going to leave in the valve. Also if you find that it seals sometimes and not others it maybe that you have a ball that is not round, I have had this. This could be caused by lobeing which can not be detected with a mic but will cause leakage
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Post by Deleted on Jan 23, 2015 13:50:45 GMT
Paul matey, you'd make a good "feed-man" for a comedy duo !!.....Quote}-- "maybe that you have a ball that is not round, I have had this"........Priceless....And as for "Lobeing"??.. well!!  |
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pault
Elder Statesman
Posts: 1,500
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Post by pault on Jan 23, 2015 16:08:18 GMT
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Post by Deleted on Jan 23, 2015 16:10:45 GMT
Oh yes- see what you mean...Interesting, -- very interesting !!. The only stage I've been on was Wells Fargo -Ha-Ha !!....Which reminds me, what's the name of the Chinese Father Christmas ??......................................... Ho Ho-Ho.
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Tony K
Elder Statesman
Posts: 1,574
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Post by Tony K on Jan 28, 2015 8:26:32 GMT
Oh yes- see what you mean...Interesting, -- very interesting !!. The only stage I've been on was Wells Fargo -Ha-Ha !!....Which reminds me, what's the name of the Chinese Father Christmas ??......................................... Ho Ho-Ho. You are Jim Hardy, special investigator presumably. Look out Dale Robertson? I think balljoint means the article on clacks in the January EiM. It is written by Gordon Smith of safety valve fame. I found the article interesting - Gordon observes the characteristics of the ball by making a transparent clack and measures the pressure drop across it when open. He then goes on to tweak it to get better results. balljoint, the comments from Uncle Hagley above are valid, as are others in many other threads - the seal bit is the same as we have been using forever. Not sure about copyright on the Gordon Smith stuff - but if you send me a PM - well you never know, amazing things do happen don't they, as William Mervin said. |
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Post by houstonceng on Jan 28, 2015 20:45:11 GMT
Rather than trying the seal with a test boiler or hydraulic tester, just suck on the inlet to seat the ball and then stick your tongue on the said inlet. If you can hang the clack on your tongue for a few seconds, it will seal at normal range of boiler pressures.
It's more difficult to get a seal for a vacuum (with one bar pressure on the ball) than it is for a pressure exceeding one bar.
I make my cracks with a separate seat and, using the ball I intend to use, polish the seat on a newspaper by rolling the ball on the seat in the same way as you'd do when writing with a ballpoint pen.
BTW. Grinding paste should've be used on the non-ferrous seat, jewellers' rouge would be the most abrasive substance that I'd use and, even then, you might not be able to clean it off completely.
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Post by Deleted on Jan 28, 2015 23:42:32 GMT
Hi Andy---------Literally a case of "Suck it and see" ??..... In the early days we adopted that same test idea at Brignorth Workshops..... The resultant 2ft long tongues came in very handy in the Bar that evening !! --LoL... This next bit leaves a lasting image in the mind >> Quote}--- "I make my cracks with a separate seat and, using the ball I intend to use, polish the seat on a newspaper by rolling the ball on the seat in the same way as you'd do when writing with a ballpoint pen".....Typos, don't you just love 'em ??.........................I find that good cleaning can be achieved in a Paraffin bath using a "stubble" brush then a 100psi air gun..A couple of sessions usually does it for me....
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Post by houstonceng on Jan 30, 2015 11:39:17 GMT
Yeh, well ! I often find my brain words ahead of my fingers and if you're not careful, the steel chucker changes clack to crack cos it can't see clak as a
God that was difficult to right as the speal cheeker wanted to change the words.
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