OmniSwivel High Flow Quick Disconnect System Fittings
The OSI QD system is NOT compatible with low flow Schrader type fittings found on BC power inflators, and also is NOT compatible with CEJN type fittings.
OmniSwivel High Flow Quick Disconnect System Fittings
The quick disconnect system by OmniSwivel International, offers high-flow performance (unlike a typical BC quick disconnect). When pushed together to form a locked connection, the QD fittings permit unrestricted bidirectional gas flow in the low-pressure hose. Pull the slide-release to disconnect and automatically seal to block gas flow from the low-pressure supply on the QD female (QDF) fitting. This also allows the QD male (QDM) fitting to be connected or released while the QDF fitting is pressurized, although connection and release are much easier to accomplish when un-pressurized. The Omniswivel version slide-release on the QDF includes a backup twist-lock mechanism that, when properly engaged, prevents inadvertent disconnection.
Each fitting is sold separately and you'll need to determine how many of which fittings you need to build your system:
The foundation of the system is the female quick disconnect fitting (QDF). The QDF accepts the male nipple with a positive locking mechanism which prevents accidental disconnection, and automatically seals when disconnected.
- The most popular version of the QDF has 9/16 male threads which attaches to a standard female low-pressure regulator hose fitting.
- The QDF is also available with 3/8 male threads which screw directly in to a standard low-pressure port on the first stage.
- Both versions of the QDF are available with a choice of either a streamlined locking nut or a larger locking nut that is easier to use.
We offer several different versions of the quick disconnect male (QDM) nipple fitting:
- The most popular version of the QDM fitting has 9/16 female threads which attaches to the standard male fitting found on most regulator second stages.
- Other versions of the QDM fittings have male threads that screw into either the standard low-pressure regulator hose fitting or the standard low-pressure port on the first stage.
- Many of the QDM fittings are available with a built-in check valve (the QD nipple is always the inlet side.)
Omniswivel check valves only allow gas to flow in one direction and are open against upstream gas flow inlet pressures exceeding 1-psi. In the event of complete loss of gas flow pressure a check valve will automatically close. The Omniswivel QD system check valves are typically used to protect against water entering the second stage and being inhaled in the event of loss of gas flow due to inadvertent disconnection or a severed upstream hose. Independent in-line shutoff and check valves that do not have a QD fitting are also available. We do not recommend use of check valves in the circumstances of most recreational diving applications.
Gas flow direction is always from the first stage outlet towards the second stage inlet. We occasionally encounter technical divers who are seeking a way to assemble QD fittings and check valves in such way as to check flow in both directions at the same time; presumably trying to minimize water intrusion while using the quick disconnects for in-water gas switching. Simultaneously checking flow in both directions is impossible because then nothing would flow under normal circumstances. For in-water switching that does not run the risk of water intrusion through the quick disconnects, consider using a gas switch block.
Dive Gear Express supplies Omniswivel products for use in recreational sport and technical diving applications. While we are aware many of their products also have use in commercial, public safety, and military diving applications, we are not qualified to advise regarding their use in other than recreational diving. For use with other applications we suggest you contact the manufacturers of the equipment you wish to use these components with for appropriate advice on their application.
Using any type of quick disconnects to switch between gas supplies while in the water has the risk of introducing at least a few drops of water contamination in the line (regardless of the presence of a check valve.) Sometime later this has the potential to cause a malfunction in any devices that are downstream of the disconnect. The diver should close the upstream shutoff or valve, perform the switch, then open the valve and operate the downstream device to clear the line. Dive Gear Express recommends that in-water switching using quick disconnects only be performed as an emergency procedure.
Low-Pressure Breathing Gas Fittings on SCUBA Regulators and Hoses
For quick reference about the low-pressure breathing gas fittings† seen on modern SCUBA regulators and hoses:
- First stage bodies have standard low-pressure outlet ports with UNF 3/8"-24 Female threads
- Some first stage bodies also have one non-standard outlet port with UNF 1/2"-20 Female threads and require a non-standard hose or an adapter
- LP hose standard inlets have UNF 3/8"-24 Male threads to mate with standard first stage low pressure ports
- LP hose standard outlets have UNF 9/16"-18 Female threads to mate with a standard second stage inlet
- Second stage bodies have a standard low-pressure inlet with UNF 9/16"-18 Male threads
- Some second stage bodies have a non-standard low-pressure inlets:
- Commercial diving full face masks may have M16x1 (aka AGA) inlets and require a non-standard hose or an adapter
- Pre-2008 Poseidon brand 2nd stages have inlet fittings unique to their design and require a non-standard hose or an adapter