Potential Alternate Exhale Valve Design

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    • #3128
      Jason Fischer
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      This is just an idea for a completely different setup of the exhale valve system in an attempt to improve cycle count MTBF. There might be some problems encountered (many of which I’ve tried to outline), or it may be completely infeasible. Also, this would take a little bit of equipment re-arrangement if that is possible.

      The idea is to use a restriction orifice (RO) and a check valve (any type should work). Instead of having the bladder which inflates through the sensing line, the line becomes a full on bypass allowing high pressure air to travel through without going through the lungs. A RO builds a back pressure which is designed to be higher than the lung pressure forcing the check valve closed during the inhalation step. When the solenoid valve closes, air pressure bleeds off and the check valve now allows for air to escape the lungs.

      To have a larger RO size, it is probably desirable to have a fairly significantly higher pressure than what is supplied to the lungs. This would necessitate probably moving the regulator downstream of the solenoid valve to increase the bypass gas pressure. A few potential issue come with this design choice. First there is a potential of high pressure gas to back flow through a leaking check valve which would likely require a second over pressure valve just upstream of the check valve. The second issue is the high pressure gas could result in fairly excessive noise which might be a show stopper.

      General issues with this design include that it will require more air flow with most of that air being wasted to just keep the check valve closed. Second the RO could provide to much restriction for exhalation causing excessive breathing cycle times as the gas pressure attempts to bleed off (this is partially mitigated by the larger RO or higher bypass operating pressure).

    • #3311
      joseph Robinson
      Guest

      I am thinking of a gravity open air pressure closed valve made with a ping pong ball and a 3d Printer. Instead of being a side by side design have it be a over / under design with the T having a ping pong ball in it. when air goes off it will fall allowing the exhale to be unblocked. when pressure air opens it will blow up and seal off the outlet. Would need to have a Custom 3d Printed T with an O-ring to allow a sufficient seal. should not be too challenging.

    • #3500
      Scotty C
      Guest

      I really like that idea, but I think a missing feature of the ping-pong ball would be achieving the plateau pressure. I believe the balloon takes a moment to deflate which holds pressure momentarily before allowing the exhalation.

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