Caution: The following report reflects my purely personal experience and can not be interpreted as instructions for oxygen diving. Whether and how you use these experiences must decided the reader!

I now use my pendulum rebreather as an electronically monitored manually controlled CCR by use of dual O2 sensor monitor system built from kits, and separate air tank to supply diluent at depth as necessary. I use a small constant O2 addition valve and add O2 manually when needed. I keep regular scan of PPO2 indicator to maintain safe range. I rarely dive to 30 meters but would with open circuit bailout. I am confident in this unit.

Pendulum Rebreather Advantages:

- Extremely simple and cheap construction - No direction valves - Easy to purge - soda lime containers easy to refill and maintain- Work of breathing is low - Operates well even in cold environments- Very low operating cost compared to other systems

Disadvantages: high dead-space with potential of excessive CO2 so this limits work effort while underwater.

How the Scrubber Works

Test Report on Pendulum Rebreather

The scrubber of pendulum rebreather works as the breathing gas passes to and fro through the absorbent material ( eg. by double use) obviously very effective. With one filling of soda lime of approximately 1.25 Kg, I usually get three low effort dives. The total dive time is usually 3 hours. So far absolutely no problems with CO2 (hypercapnia) have occurred. The high dead space has made no noticeable impact. Scrubber work-time around 3 + hours in warm water and low work effort. Scrubber time will be less with higher effort dives and I will change material after 2 hours in cold water or when working harder.

Soda Lime:

So far, I have utilized DiveSorb without indicator, Sofnolime Molecular with indicator and Drägersorb 800 with indicator. In use, I could detect no difference. The indicator reveals more dive time remaining on material. I am cautious and change scrubber material by schedule.

Breathing bag:

The material has proven to be mechanically very resistant. All adhesive compounds are permanently bonded. The volume is large enough to control the buoyancy, which means I control the buoyancy exclusively with the breathing bag. The loaded sponge cloths suck the condensation and eventual leak water well. Liquid water is after a one hour dive not included.

Respiratory comfort:

Test Report on Pendulum Rebreather

Due to the location from the counter-lung on the breast the inhalation is easier than the exhale resistance. Nevertheless, I feel that the breathing resistance lower than most commercial units. Diving in an upright position with the feet down, after lengthy dives frequently leads to the nose involuntarily releasing gas due to pressure. In normal dive (horizontal fish) position the excess pressure in the system is very low. In direct comparison to other rebreathers (CCRs) it has very easy breathing!

Oxygen Supply

Lately, I use exclusively technical oxygen. Compared with medical (in Germany), I could detect no difference. Is currently being filled by overflow from 300 bar bottles (or with big 200 bar) or from 200 bar bottles in conjunction with my booster.

Handling with PPO2 gauge:

Before I start the dive I suck the breathing bag empty, I exhale deeply, then I fill the breathing bag and breathing further from the closed loop. Only one purging! It will be achieved an oxygen fraction in a loop of about 65-70% . This fraction also changes during the dive not relevant. Of a periodic purging I can renounce. I not use an overpressure valve, I reduce the very light overpressure easily via the mouth or nose as needed. Before I had my O2 sensor system to measure PPO2 I was purging the system several times this has actually proven unnecessary. Oxygen diving with a single purge has proven safe to 8 meters and is now proven by O2 sensor.

Test Report on Pendulum Rebreather

Maximum diving depth:

Aimed after purging factor and personally accepted maximum PPO2. The generally accepted safe limits of 1.6 is reached at 10 to 11m by following the above procedures using pure O2 and without using external diluent from tank. This area is also exploited by me, but the main part of dives is up to about 8m. Leaving more surface air in the system allows greater depth to be achieved. JoJo dives are avoided, because the reduction of gas volume due to blow-off will be replaced by pure O2 when I again go deeper. When I was diving without measurement, I never dived deeper than 7-8 m.

Supplement: Pendelatmer as MCCR

The manual gas mixing on the RGU Regulator with blocked nozzle works well and is very stable. I now use air as a diluent from small separate tank. When I dive down I admix air and the PPO2 values remain constant. The dual display shows PPO2 very stable. The values remain at normal swimming very constant, it is not necessary to constantly to correct. I try not the PPO2 constantly exactly adjust, but try to achieve a range "something" from 1 to 1.3. Of course regular and steady check on the PPO2 is essential for your life! Many dives have been made with this MCCR also used as O2 CCR. So far the Pendelatmer tested up to 30m. All of these dives were without any of the known symptoms of excess CO2 despite pendulum breathing.

Test Report on Pendulum Rebreather

Conclusion:

Fun Device, very well suited for observation or photo dives in German especially for botanically interesting lakes in the area above the thermocline and small river tributaries. I have dived this in the sea with my full dry suit and this was fun and warmer than OC SCUBA. The MCCR works well for a slightly deeper view or to reduce the exposure to oxygen at ordinary O2 depths.

Update January 2007 by O.D.

This rebreather diver has designed an inexpensive constant addition valve that works well, uses a common industrial strength part and was assembled primarily with hand-tools and a small soldering torch. Very impressive innovative work! E.D.

Test Report on Pendulum Rebreather