waggy
Statesman
Posts: 744
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Post by waggy on Aug 24, 2019 8:27:09 GMT
That’s what the O ring is for in the commercial valve, as shown above. To stop air ingress.
Waggy
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Post by delaplume on Aug 26, 2019 9:51:29 GMT
Spot-on !!----------- the seal has nothing to do with drips per se but quite the opposite, literally--- and that is to prevent ANY air from being drawn back up into the feedwater ......This air / water mixture will cause the injector to momentarily knock off as the hinged flap ( For me it was on an ex-GWR 8x or 10x unit ) is released from its' running position and allows this mixture of water and air to escape via the overflow.........In our model injectors the ball valve serves the same purpose...
.Once the water is clear of air the hinged flap ( or ball valve ) will re-position itself due to the operating vacuum having been re-established and the injector will automatically "pick-up" and continue passing water into the boiler...It's quite noisy with that Bronze flap working and the reason for the air leak needs to be established ASAP or there's a real chance of damaging both the flap --- Which is reasonably cheap and easy to change, ---- OR the injector Body which can be expensive to repair or replace...
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oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 696
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Post by oldnorton on Aug 26, 2019 19:29:11 GMT
Well I hate making valves and fittings, so I cheated and bought a 1/4 turn water valve from Reeves. I took it apart this morning, and for what its worth heres a photo of its inards. Its for 1/4" pipe. Yes I agree, if you can buy something that works then why not. But interesting to see how that Reeves valve has been designed and try to guess what is going on: 1) The valve element insert will, of course, be a free running fit in the body, therefore the o-ring is essential to prevent air ingress. And there is no need for it to be a perfect seal when closed as a small continual drip to the injector is of no harm and possibly beneficial for cooling. 2) The shaft retaining stud fitting seems to have a 90 degree cut out, so perhaps there is a pin in the shaft that we cannot see? to give a positive stop to the open and shut positions. 3) That retaining stud fitting has no locknut to enable the shaft's 90 degree sweep to align with the valve body pipes. Is that why there is what seems to be a depth adjustment and locknut at the opposite end of the body? This might also make manufacture simpler as it is a through bore rather than a blind pocket. Although this depth adjustment fitting also needs sealing to prevent air ingress. Anyone have another idea what might be going on? Norm
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Post by ettingtonliam on Aug 27, 2019 0:57:58 GMT
The valve element insert is what I would describe as a'good' rather than 'free' fit in the body. There is indeed a pin in the insert which engages with the cut out in the retaining piece, restricting the opening/closing movement to 90 degrees. The threaded retaining piece is a stiffish fit in the body and is adjusted rotationally to ensure the valve opens and closes fully. You can see the hole in the valve through the pipework entry so adjustment is easy to do. That isn't a depth adjustment and locknut at the other end. Its a floor mounting valve, so thats for fixing to a steel bracket attached to the tender chassis. The bore is blind ended, so no chance of air ingress at that end.
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