Rebreather Pro

RebreatherPro Round Table Forum

The NACD recently hosted a Rebreather Summit and Round Table Forum at Camp Kulaqua (Hornsby Spring) in High Springs, Florida.  Facilitated by Rebreather Pro Jill Heinerth, the event was an opportunity to bring manufacturers, instructors, training agencies and divers together for a day of information sharing and stimulating discussion.

Pictured from left: Jill Heinerth, Tom Mount (IANTD), LaMar Hires (DiveRite), Leon Scamahorn (Innerspace), Bruce Partridge (Shearwater Research), Jakub Rahacek (Golem Gear-Hammerhead), Gregg Mikolasek (VR Technology), Brett Hemphill (Armadillo-Kiss), Mike Robertson (Silent Diving), Vince Ferris (NEDU).  (Beth Murphy Photo)

It is rare that so many of the world's elite rebreather community are brought together in this format--and the NACD, with RebreatherPro and Jill Heinerth, managed to host a lively, yet civil discussion on rebreather history, development and the future of CCR diving.  As expected, with so many passionate participants, things occasionally got a bit heated.  However, as, pictured, it seems that the Sunday morning proceedings were being overseen by a much higher authority.

Ask Jill: Diving Gloves

I get many questions from people wondering what type of gloves I like to use for cold water diving. Many rebreathers require dexterity for operation and yet thermal comfort is also important. There are two routes you can take.

Dry Gloves - If you choose them, get a ring system that allows the dry suit wrist seal to stay intact. Therefore, if you flood, it is only a glove flood and not the entire suit. OS Systems is one example of a ring system. There are many others. The sturdiest dry gloves I have seen are made by Helios. They are very abrasion and chemical resistant.

Dexterity in dry gloves is not great since you must wear layers of under-gloves to stay warm. I suggest lava wool and thinsulate under-gloves. Buy plenty, because you will get them wet simply dressing and undressing.

You can enhance warmth with a chemical heat pack placed in between layered glove liners, but don't use them deeper than 25 meters or you will get burned. Never place these directly on your skin or burns will result.

Wet Gloves ? Believe it or not, I find wet gloves to be warmer than dry gloves. Buy a 1mm BodyGlove (or other brand) five-finger glove that has rubber on at least once surface. Usually the rubber is intended to be on the outside and cloth-surface on the inside. Turn the glove inside-out so that the rubber is against your skin. Get dressed wearing these gloves only. Roll back the cuff and overlap it on the outside of the dry suit seal so there is rubber touching rubber. Immediately before getting in the water, put on a gauntlet-style, three-finger mitt on top. Your hands will stay dry and dexterity will be as good as the dry option. I prefer 7mm gauntlets with a Kevlar coating. In my experience, it?s the warmest thing going and I can still operate all my rebreather buttons, clips and valves.
 --Jill Heinerth

Vandenberg Artificial Reef in Florida Keys Greenlighted

KEYS VANDENBERG ARTIFICIAL REEF PROJECT SHOULD MOVE FORWARD

KEY WEST, Fla. -- The State of Florida is poised to contribute up to $1.6 million to satisfy a shipyard lien so a 524-foot decommissioned Air Force missile tracking vessel can be scuttled as an artificial reef off the Florida Keys, Key West officials said Tuesday.

The money to complete the General Hoyt S. Vandenberg project is to come from an Office of Tourism, Trade & Economic Development grant.

But a contract between the state and the city has to be executed and additional details are pending.

A federal judge recently ordered the auction of the ship after a contractor failed to pay Colonna's Shipyard in Norfolk, Va., for cleanup of the vessel.

Key West City Commissioner Bill Verge said efforts are being facilitated between the city, Florida and lending institution officials to persuade the judge to stay the auction while a settlement is reached.

"This has been an incredible effort (to get state funds)," said Key West Mayor Morgan McPherson. "We have to thank (Florida) Gov. (Charlie) Crist and OTTED for coming through during tough economic times."

Verge predicted the Vandenberg would be towed from Colonna's Shipyard in Norfolk, to Key West in December with a scuttling to take place in February 2009.

Coast to Coast AM

Coast to Coast AM, the most popular overnight radio show in America, and perhaps the world, has become a good friend of RebreatherPro.  Twice this year, Coast to Coast featured Jill's photography on the main page of their website. See it here.  And Coast weekend host Ian Punnett interviewed Brad Matsen and Richie Kohler on Saturday's edition. Millions and millions of listeners tuned in as Brad, followed by Richie, recounted the recent Titanic's Last Secret's adventure. You can download the stream here. (there is a fee.) Thanks to Coast to Coast AM for being a supporter of technical diving!

Tech Tip: Rebreather Soda Lime

More than just kitty litter  

Soda lime is a Carbon Dioxide absorbent used for removal of CO2 mainly from breathable gases, in medical, military, safety and recreational applications. Each of these applications has differing parameters for use and therefore slightly different product make-ups. For example, medical gas is moisturized to a degree to aid in patient comfort, therefore soda lime used in anesthesia machines has a low moisture content. Additionally, the granules are lower on a hardness scale. Alternately, the granules of soda lime used in diving have a higher moisture content and hardness. The moisture content is important as a catalyst in the process.

Soda lime itself is not a catalyst; it is an absorbent which converts the carbon dioxide from a gas to a stable solid which is retained within the absorbent canister. It is possible to predict the capacity of a scrubber canister and therefore the life expectancy for a given set of conditions. Variations in the conditions can significantly affect the predicted life expectancy. Flow rate, CO2 concentration, temperature, pressure, humidity etc. are all examples of conditions that affect the life expectancy of soda lime.

Soda lime is contained in a scrubber canister, appropriately sized for the application. The gas is passed through the scrubber and the CO2 is removed by a base catalyzed chemical reaction, converting the CO2 to Calcium Carbonate. Once the soda lime is consumed, CO2 breakthrough will occur and the CO2 level in the exiting gas stream begins to increase.

Particle size and shape are particularly important in terms of the performance of scrubber material in its intended application. Most soda lime grades are now produced with shape that offers a high surface to volume ratio. These carefully engineered shapes ensure maximum CO2 penetration into the particles, by minimizing the distance to the centre of the particle, thereby increasing the CO2 capacity of the product.  The hardness of the material is optimized to offer low-dust content, even after shipping and travel.

Another key factor in performance is the particle size distribution. Particle size has an effect on the speed of reaction, which in turn affects the volume of the reaction zone and the capacity of the scrubber. In general terms, the smaller the particle size, the faster the reaction and the smaller the reaction zone volume. However, the smaller the particle size, the greater the pressure-drop across the scrubber, which may affect work of breathing and other characteristics.

--Jill Heinerth

Are you Tweeting on Twitter?

 We have added a Twitter link in the sidebar. We want to see if Twitter is as popular as Facebook and MySpace. With all the new social media options available, we are testing those where we think we can find technical and rebreather divers. We'll try to post some micro blogs over the next month. If you are on Twitter, give us a tweet.