Guide to Gas Mask Rebreathing

You’re probably here because something doesn’t make sense. You have a gas mask, you’ve seen rebreather bags discussed online, and the combination doesn’t seem to work the way you were led to believe it should.

This guide is not a safety manual, and it is not a how-to. It won’t explain how rebreathing is done, what equipment to use, or how to make anything “work.”

However, this will explain how to fix the gasmask.

Due to the nature of the topic, I cannot go into specific detail on a public post on how to fix this issue. However I have the tempalte of the answer below. For speciic detail, happy for you to contact me via the contact me page.

Problem

Rebreathing is the act of breathing in some portion of the air you have already breathed out, rather than only fresh air.

Gas masks are specifically designed to prevent this from happening. Their internal valves and airflow paths are intended to keep inhaled and exhaled air separate. Fresh air is drawn in through one pathway, while exhaled air is expelled through a different one.

Because of this design, exhaled air is actively pushed out of the system rather than retained. As a result, a rebreather bag connected to a typical gas mask may not behave as expected — not because something is broken, but because the mask is doing exactly what it was designed to do.

Solution

Therefore, the goal is to ensure the air goes through the same port. There are many solutions to this question. Below, I will try and suggest a variety of solutions.

Solution 1:

Capture the exhaust port.

The first solution is to capture the exhaust gas with a gas mask tube, then connect the tubes together. This does require a gas mask connector on the exhaust, which is often very rare. Depending on the gas mask, KB3D offers solutions for this, including

• Exocap for the S10 gas mask (this requires zero modification of the S10 gas mask)

• N40 module from the NEXUS gas mask system (compatible with S10, FM12, FMJ08, FMJ05/MF11)

• N40 module for the Russian gas mask.

Once you have captured the exhaust gas, use a Y connector/T connector, 2x gas mask tubes, and a rebreather bag. The tubes are connected to each port on the gas mask, and the other ends of the tubes are connected to the Y/T connector and the bag.

Solution 2:

Block one valve and remove the directionality of the other.

Rather than keeping the directionality of each valve, you can (often easily) remove the rubber umbrella valve from the in-valve and then simply block the exhaust valve (cover with tape, fill with putty (Blu-Tack, etc.)). Therefore, you do not need all the tubes.