Our Dealers have found many cases of the oral nasal inhalation valve (B) and the valve body (A) of the oral nasal mask (C) installed backwards on diver maintained helmets. This is a dangerous practice with no reason or purpose for the incorrect installation.
All oral nasal inhalation valves in all Kirby Morgan® Masks and Helmets must be installed so they open inward to the diver's mouth and nose. (see pictures below) The valves serve to isolate the interior of the oral nasal mask upon exhalation to prevent Carbon Dioxide buildup in the helmet.
In the event of mechanical failure of the demand regulator breathing valve, the diver breathes from the flow provided by turning the steady flow (de-fogger) valve on. If the inhalation valve in the oral nasal is installed wrong, (opening out), the oral nasal mask will be forced against the users mouth and nose when the steady flow valve is opened. The further the steady flow valve is opened the harder the oral nasal will seal against the nose and mouth. This sudden occurrence could cause confusion and panic along with hard breathing.
This can be visually and physically checked by first looking into the oral nasal and making sure that you have the flat, smooth, rubber mushroom valve facing the inside of the oral nasal cavity. The plastic crossbar that holds the center of the rubber mushroom valve should be on the outside of the oral nasal.
Next, the valve is physically tested by putting the mask or helmet on (without face or neck seal) so the face seals on the oral nasal. There should be no resistance when inhaling or exhaling except for the very minor effort to open the mushroom valve, (and the exhaust valve in the regulator). If the oral nasal valve is installed wrong, the oral nasal mask will be drawn up tight against your face when you inhale and you will have major inhalation resistance.
All Kirby Morgan® helmet and mask manuals show the proper way to install this valve. All manuals are on-line at www.KMDSI.com. Please telephone 805-965-8538 for any additional information needed.