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  1. #21
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    Quote Originally Posted by Icon View Post
    Oh, sorry, I've used the wrong term; I meant the cross section of the O ring, which I presume is different to the one for the chamfered neck version. This must all be documented somewhere? Am I just failing at Internet?

    I'm puzzled by the (+0.50) - that can't be a tolerance, can it?
    Two answers, first part: The 0-ring sizes for the cylinder valves at the neck thread

    For countersunk (chamfer)
    Fat ones: AS 214 ID 24.99 x 3.53mm cross section and 32.05 mm OD
    and also AS 215 ID 26.58 x 3.53mm cross section and 33.00 mm OD

    For counterbored (stepped)
    Thin ones: AS119 ID 23.47 x 2.62mm cross section 28.71 mm OD

    Second part this +0.50mm tolerance this is the depth tolerance of the counterbore (stepped) depth
    The depth for the 0-ring groove to sit is 2.70mm but the drawing tolerance allows this depth to be greater by 0.5mm
    So the depth of groove can be anywhere between 2.70 mm minimum to 3.20mm maximum deep. (when using the AS119 ring)

    Now ask yourself why some here call it the rinky dink scuba dive shop industry where dive shops get to service your gear
    to the nth degree and fail it for any minor deviation in tolerance when the stuff is made all over the shop.

    Some even say that some valves are already out of tolarance before you even buy them,
    Once paid for and fitted to your cylinder the LDS can look forward to failing said already failed valve when next in for a service.
    And so it goes on.

    Alternativly others here would call these comments criticism, but as always it helps to ask what dive shop mates they represent.
    Last edited by iain/hsm; 01-05-2019 at 11:40 AM. Reason: typo fixed changed 3.35 to 3.53

  2. #22
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    Quote Originally Posted by Paulo View Post
    If it were me, I would swap the valve out for an MDE one but I am sure someone will criticise them too.
    Would you like me to start?

  3. #23
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    Quote Originally Posted by Icon View Post
    This must all be documented somewhere? Am I just failing at Internet?
    No you are being deliberatly kept in the dark for fear folk will internally inspect there own cylinders before sending to LDS for testing by having a photo of the bright shiney metal. Then you may wonder why the LDS is stating that they need a shot blast. Or take a photo of the clean clear bright shiney metal internals before dropping off at the LDS then wondering why all the flash rust after the hydro came from? Go figure. I guess on a free and open forum it would be great if we could inform all divers of these practices but getting it out on a open forum without very heavy moderation the chances are slim to zero.

    Your not failing the internet here either you wont find the information you need because there is a deliberate attempt by the industry as a whole to dum down the information given to divers to the level of simple catalogue knowledge. Just by example take a browse over this forum the light weight topics and shallow level of information given. Even then most divers dont know the difference between a fire extinguiser spec made in Turkey to a Luxfer made in Nottingham. Ignorance makes profit for the importers distributors and the LDS. Just ask anyone of them the same question you asked here.

    "What is the 0-ring size used on a M25x 2 valve thread" and watch them hawk you some overpriced Chinese junk from Beaver off the slatwall you can see the groove marks from the moulding tool its so out of tolerance. Or the other "trick" cant sell you that your not qualified its against Health and Safety rules but quite happy to jam 40% nitrox in it from a 40 year oild oily air compressor out back next the workshop sink acting as a workbench and stand for the Ginsters pie wrapper collection and retested "customer failed" cylinders for next weeks Ebay fiasco. Yep the UK LDS. Bless.
    Last edited by iain/hsm; 29-04-2019 at 10:49 PM.

  4. #24
    Established TDF Member MikeF's Avatar
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    Quote Originally Posted by iain/hsm View Post
    No you are being deliberatly kept in the dark for fear folk will internally inspect there own cylinders before sending to LDS for testing by having a photo of the bright shiney metal. Then you may wonder why the LDS is stating that they need a shot blast. Or take a photo of the clean clear bright shiney metal internals before dropping off at the LDS then wondering why all the flash rust after the hydro came from? Go figure. I guess on a free and open forum it would be great if we could inform all divers of these practices but getting it out on a open forum without very heavy moderation the chances are slim to zero.
    you cynic. been there done that when a LDS was regularly charging for cylinders being rumbled to remove rust that wasn't there before they were tested.

    I also had one shop 'scrap' a cylinder without letting me see it because the thread was out of spec. As it turned out they had tested a 3/4" BSP thread with an M25x2 thread gauge I wasn't that surprised the gauge wasn't a good fit.

  5. #25
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    Quote Originally Posted by iain/hsm View Post
    Would you like me to start?
    I would. MDE are supposed to be the Mutt's nuts. "Can't get better", "The original MDE is the best ever made" yahdie yahdah yahdah...

    Would be interested to hear an alternative viewpoint

  6. #26
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    Quote Originally Posted by PhilPage View Post
    I would. MDE are supposed to be the Mutt's nuts. "Can't get better", "The original MDE is the best ever made" yahdie yahdah yahdah...

    Would be interested to hear an alternative viewpoint
    This suddenly becomes more relevant - it's not obvious from the photos in my original post, but it turns out that this cheap knockoff of Italian tat (or whatever the original phrase was), isn't even the correct tat. I was looking at the flange of another valve (an MDE!) from another tank and I realised that it was different. The MDE valve has a flat bottom whereas the tat has an angled step. This actually interferes with the chamfer, preventing the flange from making contact with the lip of the cylinder. I found an article describing what I think is the problem here. So the tat is going in the bin.

  7. #27
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    Quote Originally Posted by iain/hsm View Post
    For counterbored (stepped)
    Thin ones: AS119 ID 23.47 x 2.62mm cross section 28.71 mm OD

    Second part this +0.50mm tolerance this is the depth tolerance of the counterbore (stepped) depth
    The depth for the 0-ring groove to sit is 2.70mm but the drawing tolerance allows this depth to be greater by 0.5mm
    So the depth of groove can be anywhere between 2.70 mm minimum to 3.20mm maximum deep. (when using the AS119 ring)
    Surely at 2.62mm C.S., the O ring isn't in compression in a 2.7mm counterbore? Even worse at 3.2mm! The O ring must start with a bit of a 'nip' to get a seal?

    Searching for the DIN477-6 thing, I found this:


    Which suggests 3.55mm for the O ring - though I realise a sketch on a web page isn't authoritative, even in German!

  8. #28
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    Missed this last post. But just to tie everything up (in knots) I think we should verify three things:

    First the specification of O-rings, are all different. You have three basic variety versions
    BS 1806 for inch BS 4518 for metric and American AS568 then add to this the French and German
    standards plus then the different polymers, compounds and shore hardness and you see where we are going.

    Second you may have a cylinder with say a M25x2 thread but Heinz variety of countersink and counter bore o-ring groves
    from each of the different manufacturers, Luxfer Nottingham, Luxfer Riverside USA DOT spec, MES Turkey All Aluminium
    Then for Steel cylinders another half dozen manufacturers

    Then you have the pillar valves again for this example say all with the same M25x2 thread but all with different "shoulders" to suit different 0-ring sizes. So a SanOSub M25x2 pilller valve will not use the same O-ring as a MDE M25x2 and a Genesis valve different again.

    So to add to the list of O-rings used for M25x2 threads

    An 814 under BS1806 inch at 23.81 x 2.62 for thin valves
    Also a 24.6 x 2.4
    Also the AS 913 at 25 x 3
    and an AS 214 at 25 x 3.53

  9. #29
    M.D., Beaver Sports (Yorks) Ltd
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    Quote Originally Posted by Icon View Post
    Hi

    Can anyone put a manufacturer's name to this valve? Ideally, I'd like to find a service kit for it:

    https://drive.google.com/open?id=1Pa...MfbXNsg5hTTDbu
    https://drive.google.com/open?id=1_y...dq2ggJoqkvce6Q
    https://drive.google.com/open?id=1Ux...6MWexT3FP1Lm6p

    Also, I'm struggling to find the proper spec for the main valve to tank O ring. Is is a BS-something?

    Thanks, as always.

    Edit - having discovered EN144, the O ring might be 25mm x 4mm, but what hardness? 90, I guess?
    Bit late I know, but sorry that isn't a Beaver valve, service parts are readily available ex-stock for all types of Beaver Valves!!


 
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