Stan Henning MCCR

Stan Henning CEDU AWARD # 9

For answering the call…
 “If  You Can’t Build A Rebreather, You Shouldn’t Dive A Rebreather.”

 It is with great pleasure that the CEDU Recognize and Present the “Honors of the Association”  Award to the following individual for outstanding achievement in the Design, Construction and Use of HomeBuilt Closed Circuit Rebreathing Apparatuses.

This award was a reason to contact Stan Hessing about his home build rebreather. Stan build a MCCR (manual controlled closed circuit rebreather) completely from off the shelf parts, mainly sewer pipes and car tyres. I am very pleased with his permission to add this unit to my homebuilder section. Thanks Stan!
I also want to thank Dr. Bob of CEDU who helped getting in contact with Stan. His excellent website offers a great source for homebuilders. Check out:
CRESTLINE EXPERIMENTAL DIVING UNIT

I got certified on open circuit in 1974 when I was fifteen years old….
I had to call and irritate the dive instructor Bob Mosbarger daily until he finally consented to let me in the class at my young age.
Back then age was an issue I have never stopped being fascinated with diving and diving equipment in the thirty years that have followed.  So building my rebreather was just the next challenge and  opportunity to grow in the sport. I designed mine specifically for the type of diving I enjoy Forty to fifty feet and with plenty of bottom time.

Except for Mark Monroe’s PPO2 display everything is completely off the shelf and was built or installed with ordinary tools…

The counter lung is an inner tube from a pick up truck tire. The scrubber unit and it’s surrounding case as well as the tank mounts and counter lung enclosure are sewer pipe PVC from the local plumbing store…
You should have seen the look on their faces as I went back over and over again in what seemed to them to be unrelated purchases…LOL!

The hoses from the addition valves to the loop are just BC inflation hoses that are attached to modified BC inflation valves. I used two first stage regulators from open circuit rigs to cut the initial pressure from the tank down to the loop. I went to the local welding supplier and bought two welding respirator masks and took the check valves from them then used more PVC plumbing to manufacture my mouthpiece. I bought the breathing hoses from Pat at Oxycheck.
I was able to get the transfer whips I needed from John at Northeast Scuba. Even though I already had my Nitrox certification I found Vance Harlow’s book …Oxygen Hacker’s Companion to be an awesome source of info. I learned lots of the technical stuff from the various web sites I found  from searching the web and that’s how I found the Crestline Experimental Dive Unit as well. Thanks to CEDU and Dr. Bob for constant encouragement ….

Here is amore technical description of the unit, complemented with some decisions made during the design phase.

I chose to make a back mounted rebreather because I wanted to make it from parts that were all readily available and also convenient…..Using an existing BC gave me the chance to not only use it as a buoyancy compensator but meant that I could use it as a mounting platform for everything from retractors to my PPO2 meter display. Also having it back mounted I can take the thirteen foot tanks out of the holders in just minutes and put in thirty foot tanks….Theoretically.. without changing the way the unit will fit on my body…..Plus, most important….LOL   I wanted it to look cool and in my opinion …..my particular design just looks better worn on the back…..I also spend most of my time when I’m diving on either my stomach or knees…..usually my knees motionless…..Just a habit I guess but I don’t move around a lot during a dive…..I’m usually aiming at something or waiting to aim at something….LOL   So the back mount is just better for the diving I do….     Of course being back mounted I can feel some slight WOB when inhaling on my stomach but no WOB is discernable at all when on my knees…..I’m sure that not only is that due to the counterlung being level with my lungs when I am vertical but also because I made the scrubber unit seven inches in diameter …Not only to lower WOB but to slow the gas passing through the scrubber material…..Hoping to preclude Hypercapnia during heavy work loads…..In fact during the first test I jogged in place and did other exercises for an hour and not only was there no discernable WOB but there turned out to be no need for baffles in the scrubber and after disassembly I found a very nice and even pattern of use in the sofnolime….I originally put a BC over pressure valve in the bottom of the counterlung hoping to be able to purge water by just over pressurizing the loop…..but have yet to get it to work right…..and have…. in fact….. removed it…..     I had some challenges with the actual construction…..I found that just using PVC glue in the conventional manner was a guarantee for leaks…..So I developed a way of gluing…..allowing to dry and gluing again over and over again that …..at least so far…..has provided strength and is water proof……and of course there seemed to be an extended period of time waiting for the glue to outgas.     The actual design of the scrubber unit is a little frustrating when it’s being assembled but having the exhaust go down through the scrubber into the counter lung saves a lot of plumbing and made the unit more stream line and compact…it also…. in my opinion….allows the gas a chance to mix ….at least a little…. from the time it’s added at the tee into the exhaust tube and is forced to travel into the bottom of the counter lung before it travels up into the scrubber material and pass the O2 sensor then into the intake hose….I had hope that this arrangement would provide….at least some….. protection against “Hot spots” in the mixture…     I had originally wanted the addition valves to be mounted…on the BC…..on my chest…..which they are when not wearing a wetsuit but with a wetsuit the BC inflation hoses I used for addition hoses are just a little short and the addition valves end up a little higher than I wanted….I’ll probably fix that later….     To make addition valves I bought BC inflation valves and cut off the oral inflator portion and plugged the hole with a piece of PVC and epoxy it in place….then used the power inflator portion to provide addition gases to the loop….     The O2 sensor is under a screen and just before a filter at the top of the scrubber unit ….I put it there hoping that the closer it was to my mouth the more accurate the reading of what I am actually breathing     After thirty minutes in cold water condensation starts to build up in the mouthpiece and makes a noticeable gurgling sound……something else to improve on later….. Without a weight belt in fresh water the unit is a little to light so I added the two yellow five pound weights you see in the photos and it’s still just a little light….  

Stan; Thank you for your amazing contribution to my website!