Crestline Experimental Dive Unit



Oxygen cylinder
The oxygen cylinder is placed below absorber canister housing assembly and the 16 pounds of  lead counterbuoyancy  weights.    The 248 litter (optional) aluminum, non-magnetic cylinder has a charging pressure of 2015 psi. (The Standard cylinder is a small  31 liter steel one-use disposable tank.  But why would any real man want one so little?)

Regulator unit
There is no regulator unit.  Instead the FEOR uses a Manual Twist Anti-Clockwise for Initiate Oxygen Addition,........Manually Twist Clockwise for Cease Oxygen Addition assembly unit. (Also know as the On-Off Valve West of the Atlantic.)  This assembly is attached to the neck of the Oxygen Cylinder.

The by-pass valve
There is no by-pass valve.  This feature  was bypassed by the engineers. 

The dosage unit
There is no dosage unit.  As the diver consumes oxygen the counterlung circulating volume reduces to a point where the diver  eventually experiences an inability to take a full breath.  At this time a physiological feedback mechanism is automatically activated and the diver reaches down with a hand
and turns  the on-off valve of the oxygen cylinder  in the On position until the counterlung is again refilled to a comfortable volume for his or her breathing. Now the unit  is ready for another couple of minutes of thought-free, hands-free breathing .   The "dosage" unit operates periodically as long as the diver wishes, or is able to do so. (Dead divers make poor Rebreather divers.)
Note: The Standard FEOR has a Push-to-Add Valve on the left side of the unit for Oxygen addition.
Other custom designs are possible taking into consideration the dexterity and prehensile ability of the individual divers' appendage in question.

FEOR (ExCap) with optional 248 liter aluminum cylinder. 

Standard FEOR with 31  liter steel cylinder. 

Diver Operating the Dosage Unit, 
and becoming "One" with his FEOR. 

Jane above and below the water with her Standard  FEOR. 

Jane Says:   "Get Your Hands Off My FEOR,
               You Want One, You Make Your Own."

The relief valve
There is no relief valve,  just  wee-wee in your wet suit.  (A a little joke son,... just a little joke.)  Though there is no mechanical relief valve, an overpressure condition IS relieved by anatomical means. Various built-in body orifices are utilized by the diver to vent excess gasses that might develop.  The nares portal of the nasopharyngeal apparatus is considered most convenient, most safe and most socially acceptable.  The Ab-Oral (anal) orifice can also be used in certain emergency situations without much long term pathology. The consumption of knockwurst or beans prior to diving facilitates this route of excess gas removal. Warning: This manufacturer does not recommend the tympanic route of  venting excess gas. 
The buoyancy control unit
With this unit the user can select an almost infinite number of settings for more or less buoyancy.  The custom made unit includes counterlungs that are engineered to to provide approximately 3 pounds of positive buoyancy when the counterlung is completely inflated.  This will correspond to a 1.5 liter volume in excess to the individual divers Vital Capacity.  In normal use the divers Tidal Volume set point  can be adjusted resulting in a  change in overall buoyancy. 
The breathing bag
The Dual Horseshoe shaped breathing bags are placed behind the neck, over the shoulder and in front of the divers chest.  This achieves low breathing resistance. Breathing bags are made from puncture resistant material, not unlike the inner tubes found on the front wheels of  Harley Davidson Motorcycles.  Recently an abundant amount of slightly used steel belted radical-radial "breathing bags"  from the Brigstone-Firestone "breathing bag company" have become available for those operations where close quarter hand to hand engagements are anticipated, and maximum puncture resistance is needed. (Warning: do not exceed high speed, overloading, extremely high temperatures and inflation pressures in the 26 psi range while using these specialized breathing bags.)
The absorber unit
The absorber unit consists of an ABS Sewer Pipe. Through extensive engineering and precision machining a Value Added Transformation results in the Highly Effective and Very Expensive  absorber housing. By naturally insulating the CO2 absorbent from the surrounding cold water with this non-metallic low thermal conducting material, the duration time is almost independent of water temperature, though not completely. It gives superior utilization of the CO2 Absorbent and a low breathing resistance via its highly acclaimed Axial Flow Design.
The absorber canister can be prepackaged, stored, and forgotten for a long time, though this practice is highly frowned upon. The unit should be prepared immediately preceding its operation , ensuring that the  oxygen is of adequate quantity and quality, and the CO2 absorbent is of proper moisture content. (May your gas be plentiful, and may your powder be dry.)
When properly placed,  the unidirectional Mushroom valves in the mouthpiece ensures low rebreathing resistance. The Dive-Surface-Valve (DSV), depending upon design,  can be shut off  to prevent leakage of water.  Note: some DSVs require two hands (additional strength)  to operate.  DSV operation testing will be conducted in order to check that the DSV selected is one that the individual user can actually handle. 

The harness is simple and uncomplicated, because it is nonexistent. The whole unit is slipped over the  neck and a simple waist strap with buckles is provided.


Height 12 inches
Width 14.5 inches
Length 25 inches +/-
Weight with oxygen and soda lime  up to 31 pounds*
Cylinder volume:   31 to 248 liters useable*
Cylinder material: Steel or Aluminum*
* Will vary depending upon specific configuration desired.

Under the assumption that the oxygen consumption is 1.0 liters/minute,  simple calculation can determine approximate duration.  (You are big people, I know you can do this.  Remember to take in consideration the liters of gas used to initially inflate the breathing loop and the liters of gas used in primary purging of the system.   Note: Individual experience may vary.) 

The FEOR set has been tested by BOB, JANE, ERICK & JOCKO of the Crestline Experimental Diving Unit (CEDU) 
June 1998, Reports  No. SA4 001 through 007 Manned Evaluation of three  manual closed-circuit oxygen rebreathers. (Robert R Iannello).

All specifications subject to change.

(1)   Please do not confuse Crestline Experimental Dive Units'  FEOR (Field Expedient Oxygen Rebreather) with other very well made oxygen rebreathers such as the   OXYDIVE by Interspiro
(2)   If you cannot make a rebreather, you should not dive a rebreather.
(3)  "To Swim Is Human, To Dive Is SUBLIME"
(4)  Further information about the Crestline Experimental Dive Unit can be found at CEDU Welcome   or Dr. Bob's Rebreather Page.
(5)  Form follows function.  Though much research has gone into the design and construction of the FEOR,  the similarity of the FEOR to other rebreathers is purely coincidental, and should not be considered an endorsement, though plagiarism of webpage design  is completely within my ethics.