• Amphibico

About Us
Since 1988, Amphibico has been providing both the recreational and professional diver with high quality and sophisticated underwater imaging equipment. Our dedicated staff, many of them divers, bring forth each day the quality and service that is required to meet Amphibico’s objectives when designing, manufacturing and providing customer support.

Address:
459 Deslauriers
Montreal, QC, ,  H4N 1W2
Country     CANADA
Phone     514-333-8666
Fax     514-333-1339
Web     http://www.amphibico.com/
Email     info@amphibico.com

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• Dive Assure

About Us
DiveAssure offers you the best diving insurance and assistance programs available today – More coverage, higher limits and less fine print than any other program offered in the USA. DiveAssure insurance is PRIMARY – as opposed to all other diving insurance programs. DiveAssure offers you the Diamond – the only comprehensive annual multi-trip dive travel program, specifically designed to meet all your diving & traveling needs through the year!

Address:
Phone     866-898-0921
Fax
Web     www.diveassure.com/new/usa/
Email     info.usa@diveassure.com

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• Dive Rite

About Us
Passion comes in many forms and is applied in many ways. Since 1984 Dive Rite has focused our passion on one thing – building the worlds best dive equipment. So whether your passion is diving beautiful reefs, deep wrecks, extreme caves, or diving them all, we make the gear to take you as far as you want to go. So gear up and hit the water with confidence — Dive It All!

Address:
175 NW Washington St.
Lake City, Florida ,  32055
USA
Phone     386-752-1087
Fax     386-755-0613
Web     http://www.diverite.com/
Email     support@diverite.com

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• Down Under Dive Shop

About Us
Down Under Dive Shop is a full-service PADI training facility, with full rental equipment, air, and nitrox fills. We are located just minutes from the beach and only about 10 minutes from the boat marina. We have a spacious 46-foot Newton dive boat capable of cruising at 18 knots. We dive the Oriskany aircraft carrier wreck and other wrecks and ledges in the area.

Address:
1129 Gulf Shores Parkway
Gulf Shores, Alabama ,  36542
USA
Phone     251-968-3483
Fax
Web     http://www.downunderdiveshop.com/
Email     info@downunderdiveshop.com

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• Hollywood Divers

About Us
HOLLYWOODIVERS offers a vast selection of unique products and diving essentials at competitive prices. HOLLYWOODIVERS has an excellent relationship with our vendors and customers. We shop the competition to sell scuba equipment at the lowest allowable prices for any authorized dealer. HOLLYWOODIVERS’ highly professional staff are scuba instructors themselves, and are totally committed to you, our customer. HOLLYWOODIVERS offers full service on all brand names. HOLLYWOODIVERS invites you to visit our showroom in the heart of the entertainment capital of the world, Hollywood, California.

Address:
3575 Cahuenga Blvd. West 104
Hollywood, CA ,  90068
USA
Phone     323-969-9800
Fax
Web     www.hollywooddivers.com/
Email     Info@Hollywoodivers.com

The following references some of my experiences during my first Closed Circuit Rebreather (CCR) course that I took in January 2006. We used the O2ptima, Dive Rite’s new CCR. My instructor was Mark Derrick, based out of Ft. Lauderdale, Florida. My open circuit (OC) diving background included: Dive master, Cave, Side mount, DPV, and Trimix diver certifications. I had been diving for more than five years and had around 1,000 total logged dives.

If you have not tried CCR diving yet, you may be nervous and/or skeptical. I admit that I was nervous about diving with a CCR. Attributing factors included real-life stories in the text books of carbon dioxide poisoning, oxygen poisoning, caustic cocktails . . . the list seemed to go on and on. The most repeated phrase was how buoyancy control was very different as compared to OC diving – I had also heard that this was especially frustrating for experienced OC divers. For example, I had heard that new CCR divers often pop to the surface because they can’t control their ascent during the last 15 feet. But to be honest with you, I wasn’t too scared about losing my buoyancy (I have been there, and done that on OC). To me, the really creepy stories were the experienced divers perishing for unexplained reasons. After all, I had zero experience at this point – If they perished, I knew I could too. Further, the anticipation of diving a unit so different from what I was used to, added to my jittery nerves. Sure, I had finished the assigned reading and then some, but the text books just did not instill in me the confidence I would’ve hoped for – I felt like I was missing a lot of basic how-to information. The texts left out a lot of unit-specific information and practical real-world stuff that I knew I still needed to learn. I had hoped that once I got my “fins wet,” that I would start to gain the confidence needed to make CCR diving fun.

Day one started with administrative needs, an orientation and academics. After the first few chapters of academics, it was time to set up the unit for the first time. We went over Mark’s assembly sequence and checklist while setting up the unit. He explained to me why the items were present on the list, and why they were in the particular order that they were in. After completely assembling the unit and performing all of the post assembly checks, I was disappointed to learn that we were just going to break it back down and go back to the academics for the remainder of the day and most likely the majority of the following day.

Day two started right where we left off the night before — scrubber theory and protocol. I must admit, I was getting quite tired of the academic portion by now – I just couldn’t wait to get to the pool and try out this piece of equipment that I have been pawing at and setting up for the last day and a half in the classroom. When we finished up the academics late that afternoon, we were off to the pool. Dipping under the surface for the first time, I almost thought that something was broken because I did not hear the normal whooshing sounds of a regulator (CCR’s are very quiet compared to OC diving, which is actually a reason that a lot of divers choose to dive CCR’s). I began to swim around the pool to get a feel for the new extension of my body and sure enough, there was a difference in buoyancy characteristics, and trim. The counter lungs added a new air space that I was not used to, which needed to be considered when changing depths. I also noticed that if I had too much gas in the counter lungs, my trim (attitude in the water column) would vary, giving me more lift on the top half of my body. What stands out in my mind from the pool session was when I completely flooded the unit. I was to recover the loop by flushing all of the water out of the exhalation counter lung’s over pressure valve in the shallow end of the pool. When I tried for the first time, all I got was a big drink of pool water. After a few tips from Mark, I was able to clear the loop successfully. Although it is difficult to flood the Extendair cannister, I managed to do so this day. I also breathed off of the unit for several minutes just after this full flood, only noticing a slight caustic taste on my tongue. That loop recovery drill quelled quite a bit of my caustic cocktail fear. In fact, this is when I started to believe that this CCR was robust and forgiving enough to be used for cave diving.

Days three through six were all reef and wreck dives out of Pompano Beach, FL. Every morning I was to set up the unit from scratch. On some days, Mark also had me set up his unit, so that I could get more repetitions in and become more familiar with the O2ptima. If you have never dived out of South Florida before, let me say what a luxury it was to have the dive sites so close to the dock. This enabled us to get out in the morning for two dives, come in for lunch and go back out in the afternoon for two more dives. After two days, I was really starting to enjoy the O2ptima, because I finally started to trust the unit. I had the new buoyancy figured out – The trick was keeping my hand near the power inflator, because it is necessary to dump and inject gas more often. At dinner on most nights, we went over numerous what-if scenarios specific to CCR diving. We discussed the important factors that cannot be taken for granted in CCR diving such as dive planning, Oxygen, Carbon Dioxide, O2ptima unit-specific equipment (Hammerhead Electronics). He knew that I would be taking the next course, CCR Tech, so we really hammered emergency procedures and methods in which gas supplies could be extended most efficiently. I began to understand how CCR’s inherently give more options to handle out of gas situations, especially while diving with a competent buddy. Most important, we covered a lot of real-world, practical matters that I just did not get from the assigned readings. In summary, without these late dinners, I seriously doubt that I would have been able to get over a lot of my anxieties so quickly.

Class is over, I am certified, and I am hooked! I dived the O2ptima exclusively for six months without a scare. It wasn’t until I went back to open circuit that I actually got a scare – at one of my favorite dive sites, Pott Springs. Due to the nature of the entrance restriction at the headspring, I had to leave my O2ptima at home and just bring some side mount gear. Sixty minutes into the dive, while swimming in the direction that I thought was the way out, I encountered a line arrow pointing toward the opposite direction! At this moment, the first thought that went through my mind was that I wished I had my O2ptima on, which would’ve given me substantially more time to find the exit. This scenario points out the biggest advantage of diving a CCR in an overhead environment — I have more time to handle potentially deadly situations. When looking at several of the most recent cave diving fatalities, I found that many of these deceased were actually trained and certified to cave dive, however still got lost and/or encountered a problem that caused them to run out of gas. Consequently, if I continue cave diving as avidly (more than 100 cave dives per year) and as aggressively as I do, my CCR just might save my life one day. Hopefully these logbook notes have helped sway you into the direction of trying out CCR diving. Do not be scared of the unknown, for the rewards may be too great to pass up.

Finally, I’ll leave you with some logistical information. Typically, it takes me forty-five minutes to set up the O2ptima for two or three days worth of diving (add five minutes before each dive for double-checks). Post dive disassembly and cleaning takes fifteen minutes. If you are interested in investing in an O2ptima yourself, plan to spend around $10,000 (US). This will take care of the purchase of your unit, your training, your start-up consumables, and other miscellaneous additions to your kit that you will end up wanting, such as bailout cylinders and spare parts.

Side mount butt plate

The side mount butt plate attaches to the bottom of the diver’s backplate extending the backplate lower, like a tail. On each side of this tail are attachment points, which are where the bailout tank’s lower connections snap to. The upper connection points for the bail out cylinders are secured utilizing the second piece of the system, the side mount bungee straps. This fifteen-inch heavy duty bungee has a quick link affixed on one end, which is secured to the top hole on the side of the diver’s backplate. A sliding bolt snap is located on the other end, which is threaded underneath the hoses coming off of the first stage, looped around the cylinder neck, and stretched up to the harness shoulder d-ring and clipped off. Shown on the harness’ waist strap are a knife and the O2ptima Secondary handset pocket.

O2ptima fits in Storm Case

The O2ptima fits in a large Hardigg Storm Case assembled or disassembled. There is enough extra space for additional gear, however not too much so as to allow the O2ptima to move around. The case can be locked and is equipped with wheels, three stationary handles and a pull out handle.

Click here.

Choosing a rebreather can be a difficult process. Before investing in a rebreather, there are many things to consider. A more sophisticated rebreather doesn’t mean it’s a better rebreather. Just like you purchased your open circuit gear, you must determine how you plan on using the rebreather. The difference between the available rebreathers on the market today is huge with respect to cost, training time, complexity, testing standards, and usability.

Rebreathers can cost $2,000 to over $10,000, which means that you don’t want to jump right in and buy the first one you see. You need to make sure that the rebreather you purchase meets your needs, operates the way the manufacturer says it does, and is reliable and durable enough to last you many years.

Determining the type of rebreather you need is the most important start. There are oxygen closed-circuit rebreathers, semi-closed circuit rebreathers, and mixed-gas closed-circuit rebreathers to choose from. Understanding the benefits, limitations, costs, and use of each of these will help you to choose the right rebreather that best fits your needs. When looking at these different rebreathers, it’s important to note the cost and training requirements, as well as your objectives and the dive environment you plan on using the rebreather in.

Once you’ve determined the type of rebreather you want to purchase, you must select a particular model or manufacturer. When doing so, it’s important to pay attention to the following: the testing standards, performance standards, certification, future service availability, and if there are spare parts available for the unit. These criteria are important in finding the right rebreather that is safe, works well, and is reliable. The test data is the most common way to find out how the rebreather performs. Several tests are used to define the performance of a rebreather:

·         Work of breathing tests

·         Canister duration time tests

·         Temperature performance tests

·         Gas control tests

·         Reliability tests

·         Computer tests

A “work of breathing” test is used to determine how difficult respiration is through the breathing loop. The movement of gas through the breathing loop is powered by your inhalation and exhalation. The amount of effort is takes you to breathe through the system can impact you significantly while diving, so you don’t want a hard breathing rebreather. The test depicts how easy it is to breathe through the breathing loop at a series of depths and with the rebreather in different positions. A series of graphs depicts its performance. Basically, the easier it is to breathe through the system, the better the rebreather.

The scrubbing agent that removes the CO2 from your exhaled gas resides in a canister on the rebreather. There are different sizes of canisters that manufacturers use on their rebreathers, which means different amounts of scrubbing agent can be used from rebreather to rebreather. The duration a canister lasts is the canister duration. Canister duration is an important factor when deciding on a rebreather. The canister duration time must be enough for the type of diving you plan on doing. When a scrubber fails to remove the CO2 from your exhaled gas, “breakthrough” can occur, meaning that dangerously high levels of CO2 can build up in the breathing loop. When this occurs, the scrubber must be replaced. Canister duration tests are performed at different temperatures and with different diver effort levels. Basically, you must find a rebreather with a canister duration time that meets the needs for the type of diving you have planned. So, the larger the canister doesn’t necessarily mean the better the rebreather.

The scrubbing agent that removes the CO2 from your exhaled gas is affected by temperature. If the ambient temperature causes the scrubber to fall below a critical temperature, the absorbing reaction becomes inefficient and the canister duration time decreases substantially. The scrubber requires a certain temperature to operate properly, so diving in very cold water can affect the operation of the scrubber. Some manufacturers insulate their scrubbers to prevent this from happening. Cold-water performance is an important factor to look at when shopping for a rebreather.

Gas control tests are also important to focus on when shopping for a rebreather. Maintaining a safe and stable oxygen level is very important. A gas control test is used to measure the frequency and amplitude of the fluctuation in the PO2 in the breathing loop. The test variables include: depth changes, respiration rate, and automatic versus manual gas addition. A rebreather that is capable of maintaining a stable PO2 within the breathing loop is an important factor to look for.

The reliability of the rebreather you decide on is extremely important and should be a big factor when doing your research. You don’t want to buy a rebreather that has a lot of problems and fails to operate regularly. Manufacturers should be putting their rebreathers through reliability testing to determine theoretical mean time between failures. Testing is always subject to the individuals conducting the tests and where the tests are performed. Because some manufacturers perform in-house tests and test for different things, comparing test data from manufacturer to manufacturer can be difficult. Understand that a manufacturer wants to show you that their rebreather works the best, so testing results can sometimes be skewed in favor of the manufacturer, not the consumer. Also, because there are no “standards” for performance and protocol testing among rebreather manufacturers, it is difficult to compare and get a complete understanding of how different rebreathers perform. Because of this, it’s important that any rebreather you’re looking at be tested with an outside testing group, such as the U.S. Navy Experimental Diving Unit (NEDU). Currently there are no minimal standards testing in the U.S., although there is in some other areas. In Europe, there is the CE (Conformite Europeene) that tests to performance standards and if the item meets their minimal standards, it receives the CE Mark. However, CE testing may be different than some of the tests mention here, so complete evaluation of all testing data should be performed before deciding on a rebreather.

If you’re looking at mixed-gas closed-circuit rebreathers with built in computers, these computer systems along with the transducers that supply the data to the computer must also be tested and evaluated for performance and reliability. Computer programs supplying display information, decompression information, EADs, etc. must be tested for accuracy and reliability. The transducers that supply computers data must also be tested for longevity and accuracy. You don’t want transducers failing or delivering inaccurate data.

The rebreather market today is in a state of flux. It’s also a very small market that, for the consumer, is in its early beginnings. As a consumer, you should beware of the stability of a manufacturer before making a purchase. Look for a manufacturer with stability, cash flow, a good, long track record, and a commitment to supporting the products they build. You don’t want a here-today, gone-tomorrow company. You’ll need support, replacement parts, and help when something goes wrong with the unit.

Source:

Boxanic, Jeffrey E. Understanding Rebreathers. Flagstaff, AZ: Best Publishing Company, 2002.

click here

Mixed-gas closed-circuit rebreathers (CCR) improve upon SCR designs. CCRs are the most advanced rebreather systems and require the most upkeep and maintenance. They are also the most expensive and complex to operate and require the most extensive training. CCRs offer the best gas economy, reduced decompression obligations, and provide extended depth capabilities.

They operate by injecting oxygen, as needed, into the loop to compensate for your metabolic oxygen consumption rate. To do this, they must monitor the PPO2 in the breathing loop. When the PPO2 drops, additional oxygen is injected to keep the PPO2 constant.

Since the PPO2 within the loop must be monitored at all times, CCRs use an electronic control device and oxygen sensors. CCRs were designed to deliver a gas mixture with a constant PPO2 no matter what the depth, which means you’re always breathing the best possible mix for the depth you’re at.

CCRs also use two gas cylinders — one for oxygen and one for a diluent that is used to dilute the oxygen in the breathing loop so that a constant PPO2 is maintained throughout the dive. The most common diluent is air, but trimix and heliox are also used in CCRs for deep diving. Whatever diluent is used, it must be capable of sustaining life if you would have to use it alone.

The electronics in CCRs are responsible for controlling the addition of oxygen through an electrically operated valve. This valve keeps the PPO2 constant no matter what your metabolic consumption rate or changes in depth. The electronics are either analog or computer-controlled and three redundant oxygen sensors are used to maintain a constant PPO2. In addition to electronic valve, manual addition valves allow you to manually add oxygen or diluent to the breathing loop in case of an emergency. Because maintaining an accurate and safe PPO2 is required throughout a dive, most systems have a display of some sort to notify you what the actual PPO2 is within the breathing loop.

Source:

Boxanic, Jeffrey E. Understanding Rebreathers. Flagstaff, AZ: Best Publishing Company, 2002.

Semi-closed circuit rebreathers (SCR) allow for the use of an inert gas to dilute the oxygen, which allows you to dive deeper. The base gas that is typically used is an EANx (nitrox) gas mix. An SCR is very similar to oxygen closed-circuit rebreathers except for the fact that they must have functionality to accommodate the use the inert gas.

One of these changes is the addition of an over pressure valve, which is used to vent gas from the breathing loop so that it stays at ambient pressure. Also, a metering valve is used to inject the breathing gas into the system. The metering valve’s job is to inject enough gas to make up for your metabolic consumption of oxygen.

There are three different classifications of semi-closed circuit rebreathers:

·         Constant mass flow

·         Respiratory minute volume keyed

·         Constant ratio

A constant mass flow SCR is the simplest and most commonly used type of recreational rebreather. They are simple to set up, operate, and maintain. The system meters a constant flow of EANx into the breathing loop. The gas mix set determines the flow rate. The over pressure valve vents gas from the loop corresponding to the flow rate amount of gas. The mass flow controller is an integral part of a constant mass flow system. If must accurately regulate the flow of gas by mass regardless of your depth. Checking the mass flow controller is part of every pre-dive check.

Oxygen closed-circuit rebreathers are oxygen-only breathing rebreathers and are the most simple design and most inexpensive type of rebreather. Because there is no helium or nitrogen to breathe, there are never any decompression requirements.

Oxygen closed-circuit rebreather systems use a valve to add the oxygen into the breathing loop. The valve is designed to keep the oxygen supply constant, meaning that as you metabolize oxygen or descend deeper, the valve adds oxygen to compensate. With this system, there is no way to vent over pressurized gas (no over pressurization valve), which means that an oxygen closed-circuit rebreather is the only true fully closed-circuit rebreather.

Oxygen closed-circuit rebreathers can be operated with zero bubbles as long as you maintain a certain depth or ascend slowly enough to make up for gas expansion. When using this type of rebreather, you must not ascend faster than your metabolic consumption of oxygen if you want to maintain bubble-free diving or risk pulmonary embolism. If you do ascend to quickly, you have to vent gas from your mask to avoid injury.

Breathing oxygen greater than 20 feet (6 m) deep is risky due to an oxygen partial pressure of 1.6 ATM and CNS oxygen toxicity. This means that an oxygen closed-circuit rebreather must be used at depths shallower than 20 feet (6 m). If you want to maintain the recommended 1.4 ATM, you cannot exceed 13 feet (4 m).

The military is the biggest users of oxygen closed-circuit rebreathers. Combat swimmers use this type of rebreather for shallow water operations requiring complete cover. Recreational use of oxygen closed-circuit rebreathers is very limited and thus is not used very often.

Source:

Boxanic, Jeffrey E. Understanding Rebreathers. Flagstaff, AZ: Best Publishing Company, 2002.<>

Rebreathers are diving systems that recycle your breathing gas. This drastically extends the supply of breathing gas by reusing exhaled gas. There are two types of rebreathers on the market today: closed-circuit rebreathers and semi-closed circuit rebreathers. All rebreathers are similar in design and have several of the same components. Every rebreather must incorporate a variable volume container that is responsible for capturing your exhaled breathing gas. This is typically what is known as a breathing bag or counterlung.

Another shared component of all rebreathers is a scrubber. A scrubber is a device that is responsible for removing the expired carbon dioxide from the breathing gas as it passes through the system. Scrubbers today typically use sodalime, which is a disposable chemical carbon dioxide absorbent.

The counterlung and scrubber make up the breathing loop, which is the path taken by the breathing gas. Other pieces of a rebreather make up the entire breathing loop and include the mouthpiece and breather hoses. Your lungs are also considered part of the breathing loop because they contain the gas during a portion of the recycling process.

The two types of rebreathers, closed-circuit and semi-closed circuit, can be broken into three different types of rebreathers: oxygen closed-circuit rebreathers, semi-closed circuit rebreathers, and mixed-gas closed-circuit rebreathers.

There are a number of training agencies that can instruct you on diving rebreathers, such as IANTD, GUE, TDI, NAUI, and PADI. All instruct on different rebreathers and different levels of diving when using a rebreather. If you want to dive a mixed-gas closed-circuit rebreather in an overhead environment, you’ll need extensive training. If you only want to dive in open water to recreational levels, such as 130 feet maximum, basic or beginner courses on a specific rebreather is what you need.

When looking for a rebreather course, you first need to first decide how and where you want to dive a rebreather. This can help you decide on the type of rebreather you need. Once you decide on a unit or two, you can then research the training required to operate the unit safely and where you need to go get the proper training. If there is a specific training organization that you want to use, you’ll have to contact them to find out exactly what type of training they offer on what rebreather, where they offer it, how long it takes to complete, costs, etc.

Every rebreather on the market today operates a little differently, even though they all perform the same function. Some rebreathers are mechanically operated only, while others use complex computer and sensor systems. This makes training requirements, costs, training time, etc. very different from rebreather to rebreather. Do your research first.