In a never ending quest to explore new frontiers, the Crestline Experimental Dive Unit instituted a "RapMod" (Rapid Modification) to a FENZY BC.
With the Swamp Fox ReFabricating a Pendulum Rebreather which he previously made about 30+ years ago, and our very own Dave Sutton constructing and field testing a "bailout BC/CCR" , the CEDU just had to jump into the Pond with a humble offering.
Last Friday (5/25/2001), an old FENZY BC was extracted from a storage bin, dusted off, and had its tube snipped, not tied. Thereafter a "Can of the Finest Scrubber Chemicals" was inserted within that old breathing tube. Thus, our old, warn out buoyancy compensator was transformed into a brand new fully functioning Closed Circuit Rebreather. (Which now has many new lives.)
Our Orange Lazarus Returns to Life. Let the Fenzy Frenzy Begin....
For this project, a simple "can of scrubber" was to be added to the oral inflator of the FENZY. The FENZY has its own compressed air cylinder to inflate the BC, and in a pinch it can be used as an "alternate air source". (Very nice BC.)
Yes it is possible to oxygen clean the FENZY cylinder. However, the addition of the Tried-and-True 31 liter ubiquitous O2 cylinder, for which the CEDU has been noted , was far more simple and had other benefits, as you will see later.
And why a Maxwell House Coffee Can you ask? Because it is "Good to the Last Drop" of course. (Officially, the CEDU does not recommend using a metal scrubber, for a number of reasons including : no thermal insulating ability thus reducing scrubber duration; reactivity with the alkali scrubber chemistry thus leading to corrosion; high magnetic signature thus leading to...you EOD know that one. But it does look colorful against that orange BC, and it was handy. Also, a little residual coffee grounds mixed in with the scrubber can only help in calming the caffeine jitters that kick in towards the end of your dive. [BTY The CEDU is a R&D, T&E, S&F, B&G Organization. The CEDU Does Not Endorse Any product ... but for the right price we can be bought. Call for details.]
The top for the coffee can was made from a 1/2" thick PVC sheet. An O-ring groove was turned, and an O-ring fitted. Threads for a PVC fitting, and Brass Barb fitting were drilled and tapped. The BC hose was connected to the PVC fitting, and Clear tubing to the barb fed the oxygen in. Even though the fit of the O-ring proved to be sufficient to hold the cover on while the system was pressurized, a turn of electrical tape was added for "piece of mind" during the diving operations. Another PVC fitting was added to the bottom of the can where the business end of the breathing hose attached. Internally, the CO2 absorbing chemicals were "sandwiched" between a thin open foam filter and compressed slightly by a thicker one. No rattling was noted in the 1.25 pounds of scrubber used.
The FENZY mouthpiece is a normally closed. A couple of bands of rubber were used to keep the mouthpiece open while diving. The rubber (bicycle tube) bands were fitted with a "tie-tie loop", used as a handle.
(L) Valve in Normal Closed Position (R) "Rubber Bands" holding Valve Open. Tie-Tie used as Handle.
Various versions of the basic design were assembled for testing.
(L) Using Existing Gas Supply Cylinder (R) External/Attached Oxygen Supply
(Manual) Mixed Gas version with PPO2 Sensor and "Wrist Mounted" Display (As Seen...)
Thus, you have many options in configuring your FENZY.
The test dives used the Standard 31 liter oxygen cylinders with Push-To-Add Valve.
(L) First dip in the WHEDU Test Tank. (R) Modified for the Ocean.
The first Pool test was conducted at the Woodland Hills Experimental Dive Unit's Test Tank, (Thank you Keith and Elizabeth), provided proof of design and system integrity, but a couple of items needed to be corrected. The breathing hose was too long, and the can with scrubber exhibited positive buoyancy. The minor annoyances were corrected by: (1) Shortening the Breathing hose, a simple snip and clamp procedure; and (2) adding a restraint to the lower end of the Scrubber Can to keep it from floating up, a simple warp of electrical tape was used. These field expedient corrections worked well.
Now to the Pond.
Dr. Bob with Dive Buddy, Photographer and Wife: Jane.
Last minute coordination was made with Photographer. Dive destination and photo shoot to be conducted in kelp patch adjacent to rocks at La Janelle Park.
(L) A High-Five is always appropriate when one sneaks up on kelp..
(R) You can almost hear the coffee brewing.
(L) A swim-by showing the top of can with fittings.
(R) Sneaking up upon those Wily and Elusive Pismo Clams.
A wonderful day in the Pacific Ocean. Wish you were here....
P.S. And yes, it was "Good to the Last Drop".
More information about Rebreathers/SUBLIME/and the
CEDU can be found starting at Dr.
Bob's The Home Page
"To Swim Is Human, To Dive Is SUBLIME"
And Remember CEDU's Mission
"To Design, Assemble and Use Homemade Dive Gear While Maximally Stroking Our Own Ego's and Maintaining the Merest Semblance of Sobriety for the Benefit of Mankind"