Here, I'm looking at features that allow divers to switch their gas supply without having to remove their full face mask. Reasons may be problems with your primary supply, but also regular switch-over such as when diving in sidemount configuration. But ... is that possible after all with full face masks that got gas supply integrated by design?
We can find several different technical solutions on the market. Each has its indivual advantages and disadvantages. Basically, we can differentiate them into these four groups:
- switching regulators using a quick connect/release connector system,
- permanently mounted backup reg,
- gas switching block (manifold),
- hose quick connect.
Switching Regs Using Quick/Release Connectors
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| Switching gas made dead simple without removing your full face mask: pull & plug. No hardware reconfiguration download required... |
- easy and quick gas switch even when wearing thick gloves:
- unlock reg (from the outside, you know...),
- remove reg,
- plug in backup reg and make sure it safely locks into place.
- only one reg is connected at a time, and always to the middle connector:
- your breathing flow is kept inside the inner mask. This constructive detail keeps CO2 levels low even in emergency situations.
- this design avoids any asymmetrical weight distribution that otherwise can reduce wearing comfort significantly.
- complete separation of primary and backup gas supply possible:
- this even allows diving with a full face mask in sidemount configuration!
- with suitable connector design it is possible to still directly breathe from an unconnected reg (for instance, Dräger P connector design). This may be very uncomfortable, but still better than no gas at all.
- requires especially prepared regs that have the necessary quick connect/release connectors.
- increased reg length due to the additional quick connect/release connector and because a space-optimized placement becomes impossible.
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| Gas backup solution with Dräger/Apeks (the second black TX100 reg is for the mask) |
The photo to the right just shows one possible configuration with a primary reg (left) and a backup reg (right). The additional yellow backup reg is for helping a buddy or in case there is a severe problem with the full face mask itself.
Both regs are connected to separate first stages to allow for full redundancy.
Important Note: While the OTS Guardian full face mask also features a quick connector this system allows divers only to connect a reg with the mask donned on your face. Unlocking and removing a reg is only possible after you have removed the full face mask from your face. Despite this quick connector system, switching regs with the mask on is impossible, as the unlocking cannot be done without removing the mask first.
My experience: While I'm no tech diver but only an ordinary SCUBA diver I still like to learn more useful things getting handed down from the realm of technical diving. Yet, the topic of full face masks seems to be a slightly controversial topic. Several tech divers were totally baffled when they saw for their first time gas switchover with a Dräger Panorama Nova full face mask. There is almost no knowledge that a suitable system is already available for a long time.
Permanently Mounted Backup Reg
In this configuration, the backup reg is permanently mounted to your full face mask.
- in order to fully separate your gas supply systems you need to take additional measures, such as valves. Otherwise your regs will still be interconnected through your mask itself. You must make sure that you can break such interconnections at any time to avoid dangerous short-cut free flows through both regs.
- asymmetric weight distribution with the main reg in your front and the backup reg on the side of your mask: wearing comfort will be much worse due to the imbalance.
- danger of short-cut free flow through both regs, either due to the available high gas delivery throughput or reg dysfunction. Counter measures:
- blocking valves which allow you to isolate a malfunctioning or free flowing reg. Attention: with blocking valves put upstream before a reg make sure that you have a separate overpressure relief valve installed for each blocking valve or first stage.
- danger of higher CO2 levels when breathing through the backup reg. Even with an inner mask, gas flow is now through the whole inner space of the full face mask. Gas flow is not directed to the primary reg any more.
My opinion: When it comes to the topic of permanently mounted regs, proper information about safe configurations seem to be lacking. Several mask manufacturers and Internet shops mention and advertise such optional dual reg configurations. What they lack to warn their customers about: customers need to make additional changes to their equipment in order to arrive at a safe configuration. Without these additional changes, diving with a dual reg configuration may actually decrease redundancy and may even be dangerous. You must avoid free-flowing and short-cut regs at all time!
As far as I know, there are three full face mask manufacturers offering a fixed-mounted backup reg configuration: Scubapro, Ocean Reef, and Dräger. With Dräger for SCUBA diving I personally would opt for the first solution, using the unique Dräger P connector quick/release system. This has the advantage of always balanced mask weight as well as breathing through the inner mask.Commendable: The only certified fixed-mounted dual reg configuration I'm aware of is available from Dräger: their Panorama Nova Dive full face mask but only in connection with their own Shark first and second stages. Aqualung explicitly points out that simultaneously connecting two Apeks TX100 regs to the Dräger full face mask is not certified and potentially dangerous. See!
Manifold
This variant using a gas switching block can especially be seen in commercial environments. A good description can be found in the manuals of Kirby Morgan for their renowned full face masks. Instead of hose quick release systems, fixed mounted manifold blocks are used to switch in case of surface gas supply problems to the bailout gas supply carried by the diver. The focus here is on ensuring gas supply of the reg (while the reg is permanently fixed to the full face mask). In consequence, this system cannot help in case of malfunction of the reg itself.
- gas supply redundancy (bailout system), but only up to but not including the second stage.
- avoids removing and plugging in gas supply hoses under water and thus avoid water getting into the regs.
- simple and quick gas switch-over.
- doesn't help in case of second stage malfunction.
Hose Quick Connect
First of all, there are two different kinds of hose quick connects ... those that can be disconnected and connected while still under pressure, as well as those that automatically get locked when under pressure. The latter type is used, for instance, by some special operations, such as rescue organizations, police, et cetera. However, in the following we will only deal with quick connectors that can be disconnected and connected while under pressure.
- comparable simple construction (with respect to manifold blocks).
- how is handling when wearing thick gloves?
- connecting under water injects small amounts of water into the reg. In consequence, this demands a reg revision next. This is okay in case of an emergency. However, when these quick connects are used on a regular basis as part of student training, what is the revision status of the connected reg?
- does not cover problems with the second stage fixed to your full face mask. This solution does not completely separate your primary and secondary gas supply system and thus cannot achieve full redundancy. Using this system you can either switch your gas supply or cut off a malfunctioning main reg. However, if your backup gas supply is your buddy, then you need to remove your mask anyway unless your buddy provides a quick connectable buddy hose. This seems to be a rather unusual situation.
