Quick Disconnects (LP) - Low Flow
These quick disconnect fittings are suitable for low flow applications using the dive industry Schrader fittings found on BC and Drysuit power inflators.
You can not use a standard BC inflator QD hose Schrader fitting to supply a regulator 2nd stage or a BC integrated alternate air source, as the device would not receive enough gas due to the flow restriction of a standard Schrader fitting.
Quick-Disconnect Compatibility and Lack Thereof
Divers are sometimes surprised to learn there is NO universal standard that defines the precise shape and exact dimensions of the quick-disconnect ( QD ) fittings used in SCUBA. This can cause compatibility issues with the connection: the fittings will not connect at all; the fittings will not securely connect and can self-disconnect without any overt user action; the fittings will securely connect but gas will not flow; the fittings will connect but will exhibit slow leaks. There is the further complication that the low-flow QD fitting commonly seen on power-inflators is not suitable for high-flow required by regulators, so QD fittings found on BC integrated second-stages use something else entirely.
- Low-flow BC power-inflator Schrader valve QD common to all BC brands sold in North America
- High-flow BC integrated 2nd stage QD used on the ScubaPro Air II
- High-flow BC integrated 2nd stage QD used on the Aqualung AirSource
- High-flow BC integrated 2nd stage QD used on the Mares Air Control
Finally there is the CEJN fitting (not shown), manufactured by CEJN AB of Sweden. This proprietary fitting is typically seen on the inflation valves of drysuits used in commercial diving.
The low-flow QD posts can be further divided into two styles: a more widely seen post with a shorter barrel and a raised bridge across the top, or a much less common post with a slightly longer barrel and a flat top. In our experience, the flat top post seems more likely to be encountered in the UK and to a lesser extent in Europe; it's almost never seen in North America or Asia. Hoses designed to fit one style of low-flow QD post are less likely to be compatible with the other. However, even within the bridge top post design we have encountered occasional incompatibilities, usually when there is many years difference in age between the male and female fittings.
First the good news... low-flow QD fitting incompatibilities are rare. All the low-pressure quick-disconnect inflation hoses we sell are compatible with the post found on our replacement power inflator as well as the inflators on all the wings we sell. (We see the most compatibility problems with these posts and various adapters.) If you are concerned about compatibility, the best strategy might be to replace the power inflator and hose simultaneously from the same source. Keep in mind that if your BC hose and power-inflator are more than five years old, best practice is to replace them anyway.
Now the bad news... high-flow QD fitting compatibility problems are commonplace. You can not use a standard inflation hose to supply a BC integrated alternate air source, as the device would not receive enough gas due to the restriction of a low-flow fitting. There are several different types of the high-flow fitting commonly seen on BC integrated second stages. If you are concerned about compatibility, the best strategy might be to replace the QD hose with the same brand from the same source as the original equipment manufacturer.
We recommend using the OEM hose for your brand of BC integrated 2nd stage, but if you can't find an OEM hose then we do stock high-flow QD adapters that allow any standard-length LP regulator hose to be converted into a quick disconnect hose for BC integrated alternate air sources. The adapter screws into the second stage end of an ordinary LP regulator hose, and the other end of the adapter is a female slide-lock fitting that accepts the hi-flow male post. Each of the different quick disconnect adapters works with one or the other of the male posts found on specific brands. A snug fit is a desirable characteristic in all quick disconnect fittings; it means the fitting is less likely to "self disconnect" or the o-ring seal to leak. However, it also means you must take care to hold the locking ring fully retracted while forcefully and completely pushing the fitting on to the post, then pull back on the connected hose to ensure secure connection. Unfortunately, in some cases the adapter might leak because of compatibility issues that are more likely with very old and/or worn posts. It the case of the SeaQuest brand Air Source, it's probably time to retire that device, you should also seriously consider retiring the entire SeaQuest BC; they are both over 30 years old.