Dorota & Wojtek(Offline)

Hi!

Encouraged by some of the „how-it-works” questions from some divers we took a closer look at a misterious connection between the inflator and the BC and on even more enigmatic o-ring that some believe doesn’t exist... It is so enigmatic that even some serivce technicians said it is not there where we think it is.

Lest see the story of “the enigmatic o-ring and its house”...

We shell begin with statement that there are two types of the connector (the coupling device) – one used for standard BC inflators and the other for AIR II type inflators. Most of us use the first type, so we will concentate on this one.

Those standard conectors can differ a little bit in shape and way it connects to the BC inflator.
Most popular one is with fitting (the top one on below picture) and the US version is a “screw sealing/quick disconnect fitting” – is there a propoer name in English f or this type? (down on the below picture)



On the „screw sealing/connection” there is a „screw” that can be easly dis-attached with flat wrench 15mm. With this tool you can start to play



The connector is built from 3 parts that easly attachable at the end of the hose.




On the above picture we have shown the only important differance between the two types, so we will concentrate on destroying only one of them...

But before we do it – few words about some leaking possibilities that we have.

Basicly there are two kinds of leakage – from the „hole” and from the „gap”.


The leakage from the “hole” comes when some bubbles fly away from a not connected hose. Here is the hole from where the bubbles escape...



The cause of this kind of leakage is misfunctioning of cutting-off valve (ventil, on picturebelow“wentyl”). We can see it peeping into an appropriate hole:



The easiest way of repairing this malfunction is to replace the valve (ventil).We can unsrew it by a misterious looking wrench/key for un-screwing valves (ventils).


...and this whole very complex operation can look like this :


And here we have our friend – Mr Ventil (or Mr Valve – for some)



1- relay that opens the valve (ventil) – it pushes the valve
2- the sealing of the seat where the valve (ventil) is screwed in
3- sealing piston with sealant


The bubbles usually come when the sealant on the piston wears out or there is a piece of debris on it... Lets look how it ... looks (the “ring” (1) with sealant have around 1mm width)



1- sealant on the piston

If there is some debris we can try to clean it off with soft brush, but most of the time the sealant is weared off so we have to change whole valve (ventil).
Other reason for this bubbling is wear-off of the sealant at the seat where the valve (ventil) is screwed in (the white thing on previous pictures of Mr Ventil) – but this comes very rarely. But it such case the whole valve is to be changed
Of course always we can change all hose, but where is the spirit of a „ do-it-yourselfer” then?


So spaeking of DIY – if you like to dis-assemble things then we can take to pieces the infator connector itself (it is good to do it in a place where small pieces will not disappear or escape.. . – like in a photo processing tray).

We need a suitable tool... and




...under we will find a spring and 3-4 bearing balls :



here all the pieces:



Let us go now to the second type of leakage at the inflator/inflator hose connection (gap leakege) – it apperars after the hose is connected to the inflator of a BC and the bubbles comes from under the gap (and it is quite often view underwater here in Red Sea and also elsewhere):


And this type of leakage is a story shrouded in mystery... of the most mysterious o-ring. Can we find it, does it exist?

And here he comes.... at the beginning „shy entry” of the o-ring. But it showes o-ring with some debris on it inside the inflator connector on the inflator hose...


This o-ring is placed quite deep but with a good light it is quite easly noticable. To change this o-ring means a lot of patience and skill – but with practice it goes quite smoothly. The ideal tool to make this “operation” is a dentists “zglebnik” (we have no idea how it is called in English – but it is the tool that a dentist checks your teeth for holes – bended metal spike).
O-ring should be pierced with this spike and taken out. A new o-ring (with lubricant) we stuff back to the hole (sorry, but for technical reasons a picture of this stuffing was quite difficult to make).

Lets take a closer look how the inflator and the connector works together:


1 – it is the nipple on the inflator (we put the connector on it) – on the picture the connector on inflator hose is halfed...
2 - enigmatic o-ring that doesn’t alow the air to come out

After connecting the inflator, the inflator nipple pushes the relay on the valve (ventil) – piston (3) – in this case the sealing valve (5) (piston with sealant described earlier) is open.

After disconecting the inflator hose, the relay (3) is released, and the spring that is inside
pushes the piston (5) into closed position, what cuts the flow of gas. That is why the gas is not escaping while the inflator hose is disconnected.

Talking about this – the process of adding and releasing air from the BC takes place a bit further on... but the things we describbed now are the tools to make it work at all.

Going back for a second to our o-ring...


Every connection and disconnection causes friction on the o-ring and as consequance of it – its wearing off. Connecting and disconnectng under pressure makes the process to accelerate. It is quite good to know especially for divers using the inflator hoses or dry suit inflation hoses to fill up the SMBs.

How we can prevent too fast wear off? Lubricate of course. Every few dives it is good to do it, but not less then every 20-30 dives. When the equipment is not used frequently – before every use.
Second way of preventing demage to the o-ring is carefully rinsing the inside of inflator connector hole – even a small cristal of salt or a sand grain can make the demage of our sealing thingie... It is especially important when we assembble/disassemble the equipment on “battle field of diving” somewhere on the beach – the lubricant inside will welcome with pleasure anything that it can stick to itself.

Here is the way we can clean and put lubricant in the hole





Wishing you good relationships with all your enigmatic o-rings...



D&W

mstroeck(Offline)

Holy crap, I'd say that covers the topic pretty exhaustively. Thanks for that, shiny thing incoming.

rjack(Offline)

Have a shiny. I didn't think anyone could write a dissertation on a LP connector. But you managed very nicely

I have never seen the screw type in the States, but then again I don't work in a dive shop.

Richard

LCF (Online)

What a wonderfully informative piece! Thanks for taking the time to put that together with the photographs.

tanto(Offline)

Uau, you should write a book!

Mal Bridgeman(Offline)

Is Hurghada a bit short of intellectual stimulation?

Mal

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Opinions and beliefs are correct at the time of posting but are subject to change without any notice or obligation on the part of the author.

Dorota & Wojtek(Offline)

Thank you Guys

That is nice that you find our "piece of information" useful. We are open for any suggestions and comments - as we said in our welcome post - we are maniacs, simply obsessed with testing , trying , destroying things

Best,

D&W

ps....and Hurghada is extremely stimulating... you can not imagine what you can expirience here (startings from electric switches under showers... )

MonkSeal(Offline)

I have new hose without those three little balls (I've lost them somehow). Do you have any idea where to get them (except from other hose)?

Thalassamania(Offline)

Truly a wonderful piece of work, I now know something that I wanted to know but was too lazy to find out. Thanks again.

BTW: The little valve thing is, I believe, a "Schrader Valve," the same thing you find in car and some bicycle tires.


In the photo below are two different types of Schrader valve cores, a "long" core which has a relatively large exposed spring, and a "short" one with an internal spring that isn't visible.




Below is a formerly long Schrader core which has had its lower stem and spring cut off. Note that the valve is open. This is the kind of core I use in all my Schrader valves.

It seems that new Schrader tubes nowadays rarely come with a "long" core, but they are interchangeable, and the core should last many times longer than the tube itself.



Photos and text are from Link (Richard's Index Page)

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nic_the_greek(Offline)

Does anyone know where I can buy these o-rings? I tried my local shop and Underwater Explorers in Portland without success. The o-ring seems to be a very specific size and thickness. The ones I saw were all thicker and either slightly bigger or smaller. I'll see if I can post a picture, later, to illustrate my point.

Cheers/Nic

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