Gregg140 Posted August 7, 2024 #1 Posted August 7, 2024 I have this WWII A-14 oxygen mask that's in really good shape. Looking at the inside it seems as if the two inhalation paths are simply covered with a rubber flap - doesn't seem to be any sort of valve involved there. See the first picture. The second picture is attempting to show what's under the flap. Is that how the exhalation was blocked from the inhalation path? By pressurizing the interior of the mask with your breath and closing off the path with the rubber flap? And is thre no other valve involved? What kind of valve is used for the exhalation path going out of the mask? Thanks
RWW Posted August 8, 2024 #2 Posted August 8, 2024 This is from AAF Manual 55-0-1, Reference Manual for Personal Equipment Officers, 9 December 1946. "Face masks for use with demand regulators are somewhat similar to a gas mask in operation, though not in design. A single outlet valve is the only mechanically operating feature. The valve is simply a circular rubber flap which opens upon exhalation and closes on inhalation. Proper operation of the entire system thus depends upon suction created in the mask and regulator as the user inhales".
Gregg140 Posted August 8, 2024 Author #3 Posted August 8, 2024 Ok so then it seems as if both inhale and exhale valves are simple flaps and opening/closure of the flaps is done by breathing in and out creating pressure differences.. Thanks
RWW Posted August 8, 2024 #4 Posted August 8, 2024 The inhalation valve (the demand valve) is actually in the regulator, not the mask, which is opened by suction when the user inhales. There were two types of regulators, Straight Demand which were used only on portable oxygen units and Diluter-Demand which diluted the oxygen with controlled amounts of atmospheric air for a more economical consumption of the oxygen supply. The flaps I think you are calling the inhalation valves were more like baffles to keep from having a "rush" of oxygen to the user when breathing. The only valve in the mask is the exhalation valve. When the user inhaled, the inhalation valve in the regulator opened to allow oxygen to flow into the mask. This inhalation created a suction in the mask closing the exhalation valve in the mask. When the user exhaled, the reverse happened. The pressure created by exhalation closed the demand valve in the regulator and opened the valve in the mask allowing "used' air to exit the mask.
Gregg140 Posted August 8, 2024 Author #5 Posted August 8, 2024 Ah I see so all the difficult management is in the regulator and not the mask. This suggests that the mask might be usable if all the rubber is in good condition an dyou have a good regulator. I wonder if this mask can be connected to modern regulators.
RWW Posted August 8, 2024 #6 Posted August 8, 2024 That is correct! The regulator was the key to the system. There were a couple of types of male fittings on the end of the mask hose. The first fittings were a prong type which was later replaced with the C-ring connector. The C-ring type connector is still used today, so I believe your mask would connect to a modern-day system.
Gregg140 Posted August 8, 2024 Author #7 Posted August 8, 2024 This is the connector at the other end of the mask - I take it this is the "C" connector you are referring to?
phantomfixer Posted August 11, 2024 #9 Posted August 11, 2024 The A-14 mask will plug into a modern … er late 20th century USAF walk around bottle… and if I recall I remember I plugged the mask into the C-5 crew hose… the hose connector has not changed… over the decades… the CRU-60 is the interface between old school hose connector and 3 pin mask hose
phantomfixer Posted August 11, 2024 #10 Posted August 11, 2024 Even the Raptor uses “old “ style hose connector with a CRU-60 point is, you could don an A-11 (with updated receivers)and A-14 mask and function in a modern jet… with limitations of course
pararaftanr2 Posted August 21, 2024 #11 Posted August 21, 2024 What you are seeing is a baffle, added to late production A-14 masks, to help prevent freezing of the mask from exhaled breath at higher altitudes. Looking at the mask from the front, you will see the set of two black plastic "rivets" used to secure the baffle on the interior. Looking at earlier vintage masks from the front, those "rivets" are not there. This was known as the "8th AF modification" and was done at production, not in the field.
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