History of LPI connections

[LPI researcher]

Hi all,

I am conducting an engineering review looking at redesigning the connector from LPI hose to BCD inflator.
Those of you who are wise in years and experience; do you remember connectors for past times or any that specific companies opted for different to the standard ones we all see today?
Very open to discussion....

Many thanks and happy new year!

Jake
PADI MSDT and student engineer.

 

[LPI researcher]

Also, does anyone know any info on this pictured connector?
Any idea why these stopped being used?

 

[-JD-]

Also, does anyone know any info on this pictured connector?
Any idea why these stopped being used?

Is that a "standard BC nipple" connector or one of the larger AIR2 / Octo-flate type connectors.
Looks pretty similar to this example:

https://www.divers-supply.com/trident-adapter-reg-hose-mares-inf.htm

 

[Akimbo]

As I recall, manufacturers first used off the shelf QDs (Quick Disconnect) fittings. The first ones I saw used in recreational diving were on the Poseidon Unisuit (drysuit) in the late 1960s. Power inflators in the US started to show up on semi-drysuits, which looked like they all came from the same OEM (Original Equipment Manufacture).

Divers began to replace the mouthpieces on their Bouée Fenzy horse collars with these power inflators, which inspired the first BCD (Buoyancy Control Device). I believe that the ScubaPro Stabilizing jacket was the first QD in the US market to be incompatible with the QD used on these OEM power inflators. These guys may have different experiences: Ping @couv @herman

 

[Couv]

Hi all,

I am conducting an engineering review looking at redesigning the connector from LPI hose to BCD inflator.
Those of you who are wise in years and experience; do you remember connectors for past times or any that specific companies opted for different to the standard ones we all see today?
Very open to discussion....

Many thanks and happy new year!

Jake
PADI MSDT and student engineer.

Hi Jake,

First decide if you need a connector that is high flow or low flow. High flow connectors are found on dual purpose units that serve as a inflator and a regulator. (Think AIR 2 and the ilk)

The most common inflator connectors cannot provide enough flow for a regulator. Instead, inflator regulators use a larger bore in the male and female components. Personally, I do not see a down side to having the larger fitting.

Compare the above to a standard male qd fitting and it's easy to see why. (Dive Gear Express photo)

In addition to the extra gas it can handle, the female connector is usually much easier to rebuild/service than the dinky snap ring/scharder valve/embedded o-ring design in the "standard" inflator quick disconnect.
(DGX photo)

You might guess that a connector that is user serviceable is important to me. Other than that, one that is easily replaced-as in the type that screws into any length standard regulator hose.
(DGX photo)

Next, I like a connector that can be disconnected with one hand-with gloves if necessary.
This one pretty much fits the bill, except that it is not high flow:
(Again, thank you to DGX)

Icing on the cake it to have the connector on the outboard side of the inflator rather than the inside.

Now, some features I've encountered over the years that I did not like:
US Divers had a proprietary hose with the male end plugged into the female q.d. mounted on the vest. If you had an issue with either component, you were sol until you could get back to the dive store and replace it.

Small spring loaded connectors. Worked fine for just "push and play" connections, but disconnecting them was like working a puzzle at times.

I'm sure others will be chiming in.

Edit with a picture of a couple of designs I would avoid. The one on the left has a spring type holding devise rather than the standard ball bearings. The one on the right is too small for high flow, too large for a standard male fitting.

 

[rjack321]

Also, does anyone know any info on this pictured connector?
Any idea why these stopped being used?

These are still available. As others described they are "high flow" connectors, used in Air2 and other dual purpose power inflators, for a while Apeks was using them in drysuit inflators too.

The "Standard" BC nipple is actually an automotive shraeder valve with the ball bearing locking collar on the outside. Also used in refrigerant recharge systems, air conditioning systems, bicycle tires, and more. Since shraeder valves were invented in the 1890s there really never was a time "pre-shraeder" in the scuba industry.

 

[Angelo Farina]

My first BCD was a DIY project based on a standard tyre bladder (of a Fiat 500 of the seventies).
The LP hose was equipped with a standard press-to-open valve and a connector for the Schrader valve of the tyre bladder:

It worked well for many years...

 

[emoreira]

The larger bore QD used in Octo integrated Power Inflators, like Air2, TUSA Duo Air and others, or many Drysuits inflator valves, are the CEJN QD
Inflator hoses with DIN size QD use the standard schrader valve. Also many inflator valves use schrader valves. Schrader valves, as mentioned are used for car tires, Air Conditioning inspection valves, etc. In those applications, that valve is sparsely used, not like in a BCD inflator valve, which is oftenly used, much more in a BCD used by a dive school. This leads to premature inflator valve malfunction (leaks and/or bladder self inflating).

 

[Akimbo]

August Schrader History​

There is a diving connection here. A. Schrader’s Son was an American Manufacturer of heavy-gear diving helmets decades before he patented the Schrader valve in the United States in 1893.

Schrader, Morse, and Desco were the leading manufacturers of the US Navy Mark V helmets through World War II, along with other models based on their design and those of Siebe Gorman in England. I trained in several Schrader hats in the early 1970s.

Quick Disconnect Couplings History​

Quick Connect or Disconnect couplings were developed for military use during World War II and various options included Schrader valves at one or both ends.

 

[Couv]

This leads to premature inflator valve malfunction (leaks and/or bladder self inflating).

@emoreira I agree with your post with the exception of the quoted comment above. Yes, a leak can occur if the Schrader valve fails-but only if there is another seal malfunction or if the QD is not connected.

Self inflating of a bladder is caused by a malfunction in the inflator valve. It is worth noting that balanced valves, such as found in the Scubapro and Atomics inflators, are less prone to failure than the common inflator devices.