Oral Nasal Valve Assembly

The two oral nasal valves, part #510-552, must be installed correctly in order to provide gas flow in the proper direction. The flow through the valves must be from the interior of the helmet into the oral nasal mask. This will allow the diver to breathe the gas from the muffler/free-flow, part #905-027, freely, yet help to reduce the amount of carbon dioxide inside the helmet. If the two valves are not placed properly, this could make it difficult to breathe the gas supplied by the muffler/free-flow, and expose the diver to an excess of carbon dioxide. This could lead to exhaustion and blackout.

Oral nasal valves in Miller helmets must be installed so they open inward to the diver's mouth and nose. 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 muffler/free-flow valve on. If the oral nasal valve in the oral nasal mask is installed wrong (opening out), the oral nasal mask will be forced against the user's mouth and nose when the muffler/free-flow valve is opened. The further the muffler/free-flow valve is opened, the harder the oral nasal mask 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 mask 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 mask. 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 an 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.

If you have any questions about the placement of oral nasal valves in your Miller helmet, contact Miller Diving at www.MillerDiving.com or telephone 805-965-8538 for any additional information needed.