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can anyone help with these gas connections?
i know there are a few clever engineers out there in the diving world!
the one with the valve is an inlet and the red handle should open/close tank pressure going in,
the other is ... well i have no idea!

what i need is to connect the inlet to a BOC F size cylinder which from looking at the BOC website the bullnose regulators have 5/8" outlets and this seems to be a 1/4" inlet,BOC seem to have an adaptor although without callinmg them i cant be 100% sure i have the right item but the hose between them seems to be female both ends but it would need to be male both ends and ideally id like as few connections as possible?

greens to anyone who can solve my little puzzle
any ideas ?
 

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1st fitting is out of focus so is the second
dose that help?
 

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I can't tell fro the photo's, but if i was to be presumptious i'd say you were trying some home blending. If that's the case, the cheapest way i have found is to get something like this: AP Valves AP8K Oxygen Decanting Whip by AP Valves (Buddy) with a decent gauge and an adaptor like this (also available from SAP, Southampton): Male UK Bullnose - DIN Adaptor OXYGEN REBREATHER NITROX on eBay (end time 05-May-10 13:10:21 BST)

Do a search of Woz's posts with regard to Keller gauges.
Just out of interest why the Male adaptor and not the Female ?
I only ask as I have one of these whips and think the female would be of more use.
 

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Discussion Starter #5
Thanks Steve you have given me some interesting reading
but no its a work project nowt to do with diving

And no Fred no help at all but I suspect you knew that
 

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capt morgan, if you look at the both of the pictures in the ebay links you'll see the ends are different. Your link shows a flat DIN fitting ( despite the item description) and the piccie in my link shows a tappered end to seat in the bullnose end of the valve
 

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can anyone help with these gas connections?
i know there are a few clever engineers out there in the diving world!
the one with the valve is an inlet and the red handle should open/close tank pressure going in,
the other is ... well i have no idea!

what i need is to connect the inlet to a BOC F size cylinder which from looking at the BOC website the bullnose regulators have 5/8" outlets and this seems to be a 1/4" inlet,BOC seem to have an adaptor although without callinmg them i cant be 100% sure i have the right item but the hose between them seems to be female both ends but it would need to be male both ends and ideally id like as few connections as possible?

greens to anyone who can solve my little puzzle
any ideas ?
Don’t know about clever engineers but I guess they would want to know first what gas you intend to connect up to and what pressure. Most gas groups use different size fittings depending on the gas, it’s group, the bottle pressure and it’s application.

A BOC size F is only a size it could contain Heinz variety of different gasses.

Of the photos one you can’t see, but the other with the red handle is known as a WOG valve used for low pressure water oil or gas only at a guess max 40 barg. It should be marked on the side with a DN number that will tell you the max pressure. If you use that WOG valve on HP gas it will explode, also if you mix up the inlet from the outlet on the WOG valve you can also shoot out the ¼ turn steel ball like a 00 shotgun shell.

When you say you want to connect the inlet to the BOC cylinder don’t you mean outlet as these cylinders are not to be refilled by customers.

My WAG is to know first the gas and the application you want to use it for, the fittings required are then so much easier to work out. Oh and IMHO E-bay is the last place you want to go. Iain Middlebrook
 

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Discussion Starter #10
thanks iain very helpfull info

its a lab pressure based experiment in work (university lab) so absolutely no way id touch ebay it needs to have the appropiate health and safety paper trail .
it is indeed a low pressure tank max 1 bar but i dont intend on using it above .5 bar of air
(sorry i missed that bit,should have realised considering every other regulator we have is differnt depending on gas!)

what i meant by the inlet was the1/4 " inlet to the piece of equipment im working with and by the 3/8" outlet i meant the outlet from the bullnose air regulater supplied from BOC
Its these 2 items i wish to connect the regulator reducing the pressure from the cylinder to .5 bar
i dont have acces to it for the DN number but will check that out on monday as well as calling BOC when i have a better idea what im after

very helpfull

many thanks
 

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For a university I can understand your concerns and responsibilities regarding safety. But it’s the small details that are important.

Your greatest risk IMHO is in using the BOC bottle, it’s a large stored volume of high pressure air and the reducing regulator working correctly to pressurize your small 0.5 bar low pressure vessel. P1 v1 over P2 v2 is the concern in the event of a regulator leak or pressure overshoot.

Normally your safety audit will require a low pressure relief valve but be careful as it should also be large enough to discharge over the capacity factor of the regulator.
Especially if you have a big 200 bar HP cylinder and a small 0.5 bar test chamber.

Another big risk is the capacity factor or CV rating of the regulator and its type, in cheap single stage regulators as the pressure P1 in the cylinder drops the regulated pressure downstream P2 increases. In higher quality two stage regulators this overshoot is much reduced. IMHO you should be using a two stage regulator. Yet if a large enough test chamber is being used then the risk is reduced but as the bottle pressure decreases the flow to your test chamber increases.

Of course a risk depends on the burst pressure of your test chamber but also the pressure cycles it is designed for.

For pressurizing more “interesting” gases say such as hydrogen most labs prefer to use small oil free laboratory gas compressors rather than using high pressure cylinders.
A little 240 volt 0.5 hp 3 stage gas compressor will compress at a set rate of say 7 litres per minute and cannot compress your test vessel any faster also a pressure switch will automatically switch off when they have filled your test chamber.

For safety the inlet pressure of sample gas to the compressor is very low, the “sample gas” is no more than 2 bar yet can compress up to 170 bar. Again for safety the “wetted volume” of the high pressure parts in the compressor is tiny and pressure relief valves are also fitted for safety at each stage of compression.

A photo of your test chamber and its material, steel, aluminium or plastic would resolve most other mechanical considerations and allow you to make the correct choice and type of fittings to be made. Iain Middlebrook
 
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