CCR FAQ - rEvo

Prepared by Mark Derrick, CCR Instructor on Staff

How much does a rEvo cost?

A better wording of the question might be 'How much does it cost to switch from an open-circuit diver to a rebreather diver?' The price of the rebreather itself can vary significantly depending on configuration options. Plus there are usually additional equipment purchases depending on what existing gear you have that can be re-purposed. Training, particularly if travel is required, will be a significant cost. I suggest budgeting a total amount of about $15,000.00 minimum.

Which model rEvo should I purchase?

There are both a manually operated version and a hybrid version that also adds oxygen automatically using the Shearwater Research electronic ppO2 setpoint controller. The two versions are further available in a choice of three different sizes. Unless you are exceptionally large physically, I suggest the "rEvo III micro FT" fully automatic hCCR. All rEvo units include a backup ppO2 monitor, however technical divers should strongly consider adding connectivity to support a Shearwater Petrel or NERD backup dive computer. Divers with a long torso and drysuit divers should consider requesting longer hoses on the manual gas addition block.

How long does it take to get a rEvo rebreather?

The rebreather base unit will usually be available for shipment within four to six weeks after receipt of order. Occasionally, demand or logistics will cause brief stock-outs of the base unit but delays beyond 30 days are rare. Accessories and spares are usually available for immediate shipment.

How much does the rEvo rebreather training cost?

There is wide variation in training costs due to a variety of factors, although location (and thus indirectly the costs of instructor insurance) is often a major influence. There is a geographically diverse group of instructors and you might have an instructor in your local area. Typically, the cost ranges from $1500 to $2500 for instruction only, plus out-of-pocket costs. If you prefer to learn about your rebreather at Dive Gear Express in Pompano Beach Florida, training can be organized to accommodate your schedule and rebreather courses run every month.

Can I buy the rebreather without training?

Yes, but you won't be able to dive the rebreather until you are trained. Every rebreather requires formal, model specific, training in order to competently dive with the equipment; ordinary open-circuit training is not adequate. If you are not already certified for the rebreather, per manufacturer requirements you will receive a disabled unit with a critical component necessary for diving shipped to your instructor. If your instructor agrees to accept liability for delivery, we can also ship the entire unit directly to your instructor.

How much does routine maintenance cost?

You should expect annual routine maintenance costs of approximately $350 annually. Basic maintenance is taught during diver training and you will also need to replenish consumables such as sensors, lubricant and disinfectant from the annual maintenance budget. The two first stage regulators should be serviced annually and the entire unit has a required service interval of five years. These services must be performed by an authorized service center.

What consumables do you recommend?

The recommended consumables are: Molecular Products 8-12 mesh loose granular carbon dioxide absorbent, Steramine for sanitizing the breathing loop, Tribolube 71 O2 Compatible Lubricant for O-ring seals, and rEvo brand CR22D galvanic chemistry oxygen sensors. The Shearwater electronics require one AA size and one 9V size consumer grade batteries such as Energizer or Duracell.

How much do the consumables cost?

As with all rebreathers, the major consumable cost is CO2 absorbent. A full six pound absorbent load costs about $25 and can typically can be used for several sport dives. There are other smaller costs such as gas fills and batteries. Keep in mind that for both open-circuit and rebreather divers, consumables costs are usually insignificant in relationship to the investment in the equipment, training and other diving costs such as boat charters and travel.

How long does the absorbent last?

If determining duration by wall clock time only, then the absorbent duration is three hours in water temperatures greater than {59°F | 15°C}. When using the rMS scrubber temperature monitoring system, divers are reporting absorbent duration times of four to six hours. The duration in actual use depends upon many factors related to the individual diver and specific dive conditions. These are observations of what experienced divers are reporting and in no way suggests exceeding manufacturer recommendations or that novices should expect these durations.

How does the rEvo dual scrubber system work?

The rEvo design divides a six pound absorbent load between two self-pack axial flow cassettes that can be cycled in a manner such that once the top cassette has been expended, the bottom cassette is promoted to the top position, the expended cassette is emptied and refilled with fresh absorbent then loaded in the bottom position. This efficiency results in very minimal waste of unused absorbent, unlike other scrubber designs where typically one-third to one-half of every absorbent load is unused yet must be discarded. See rEvo Dual Scrubber Cycling (pdf) for more information.

What about the possibility of a 'caustic cocktail' with the rEvo?

The rEvo is a modern CCR design that also includes several features to minimize risk of water entering the breathing loop. During training you will learn how to setup the unit and check it's integrity using a pre-dive checklist. Once you are trained, inhaling a mixture of CO2 absorbent and water while diving is very unlikely. The 'caustic cocktail' is a concern from an earlier era of rebreather diving that has been overly dramatized, akin to the concern new divers express regarding 'shark attack'.

How available is the absorbent?

In the global economy, absorbents are sold and shipped all over the world. As a result, supply logistics for absorbent is becoming less of an issue. The number of dive shops that stock absorbent is consistently growing, and you can always order on-line to be delivered to your door or directly to your travel destination.

Does the rEvo have a CO2 monitor?

No. CO2 monitoring is a 'bleeding edge' technology that will begin to appear in recreational rebreathers in the next few years but as a practical matter the merits of CO2 monitoring are unproven. You should not confuse a CO2 monitor with a scrubber temperature monitor. When used correctly, the rMS scrubber temperature monitor option for the rEvo will predict scrubber duration well in advance of any CO2 breakthrough caused by exhaustion of absorbent capacity. However, the rMS does not provide any information or warning regarding actual CO2 levels in the breathing loop.

What cylinders should I use?

The rebreather will accept 2L or 3L cylinder sizes using standard 'inline' DIN valves. The rebreather may be configured with steel 17 or 23 cubic foot (2L or 3L) cylinders, and these are the cylinders I generally recommend. Smaller stature divers may prefer the 2L cylinders. Aluminum 13 or 19 cubic foot (2L or 3L) capacity cylinders minimize the total weight, but most divers find they must add weight to adjust their in-water buoyancy and trim. Most wetsuit divers find having the steel cylinders requires little additional weight and trim can usually be made perfect simply by slight adjustments to the harness. Although some divers have used non-DOT carbon fiber cylinders to reduce the total weight, I recommend against this practice for both safety and logistics reasons.

What BC should I use with the rEvo?

The rEvo includes a good quality webbing harness and wing style buoyancy control system that most divers will find meets their needs. The rEvo will accept any wing, harness and backplate system that mounts using 11-inch centers, however using a different wing and harness can change the position of the unit on the divers back and thus may change work of breathing performance. Some divers choose to replace the native harness and wing with a very comfortable Dive Rite TransPac or Nomad system. Technical divers carrying multiple bailout and deco cylinders may require larger wings and should consider redundant bladders.

Does the rEvo support an external PO2 monitor and backup dive computer?

The rEvo offers a upgrade to provide a Shearwater NERD2 full dive computer HUD rather than the LED display or a Shearwater Petrel wrist mount CCR dive computer. The additional dive computer provides independent redundant monitoring of PO2, as well as redundant depth/time and decompression status.

What about a Bail-Out-Valve (BOV) option for the rEvo?

rEvo now offers an optional low weight BOV with single-hand operation and work-of-breathing similar to the rEvo standard DSV. Bail out valves can offer benefits, especially for new CCR divers, but some experienced CCR divers consider them to be counter productive in technical diving by adding complexity and degrading performance. Regardless, divers should always carry off-board bailout.

What is the rEvo maximum dive time and depth?

Rebreathers carry many hours of breathing gas regardless of depth. The rEvo can accept auxiliary outboard plug-in gas as well, so dive time is no longer limited by gas volume. As with most rebreathers, the rEvo diver is typically limited by the duration of the CO2 absorbent, so multi-hour run time dives are routine. As with open-circuit nitrox diving, rebreather divers must also monitor their decompression and oxygen exposure; depending on the dive profile these may also limit the dive time. The rEvo rebreather is suitable for diving at all sport depths and has been qualified to a depth of {330 feet | 100 meters}. Although the rEvo can function well beyond sport depths, as with any rebreather there are numerous additional considerations for deeper diving.

Is the rEvo capable of diving with mixed gases?

Yes, the rEvo can use either nitrox or trimix diluents that may be either hyperoxic, normoxic or hypoxic. Because the rEvo is a fully closed-circuit design, the use of mixed gas diluents is very inexpensive compared to open-circuit. Personally, I recommend and teach rebreather divers to substitute normoxic trimix diluent (21% oxygen, 35% helium) rather than air even within recreational sport limits for the benefits of reduced narcosis, improved work of breathing, and improved scrubber function. However, use of anything other than normoxic diluent or diving outside of recreational sport diving limits requires significant additional diver training.

Does the rebreather take a long time to maintain?

Yes and No. Many rebreather sport divers find they spend noticeably more time on equipment compared to open-circuit because the rebreather diver must always be careful and disciplined about maintenance. However, most experienced rebreather divers will find pre-dive and post-dive maintenance for the rEvo to be fast and easy. If you have been habitually careful with your open-circuit dive equipment and treat your equipment with respect, as an experienced rebreather diver you will spend only slightly more time with your maintenance than you did with open-circuit.

How well does the rEvo rebreather travel?

The rEvo rebreather housing is not easy to separate into component pieces so typically the assembled Micro unit, weighing approximately { 35 lbs | 16 kg} not counting cylinders, is usually packed as a separate piece of luggage. When packed in luggage it is possible to stay under the single bag weight limit of most airlines, and the Micro unit will even fit within the carry-on luggage dimensions of some airlines. Regardless of the brand of rebreather it can be annoying to travel with cylinders because they are carefully examined by security personnel, and occasionally even confiscated. You may prefer to rent cylinders at the destination or ship your cylinders ahead.

How is the rEvo different from other rebreathers?

All of the major rebreather models are good quality units. There is no perfect rebreather; they all have strengths and weaknesses that make each uniquely more or less suited to your needs. Key design features of the rEvo include built-in backmount counterlungs, dual scrubbers, and highly redundant electronics. The rEvo III is a richly featured and proven model from a well established manufacturer. The rEvo is a European design that favors the sport diver with intentions of continuing on to technical diving. As an independent dealer, we stock spares and consumables with online ordering and same day shipping.

Is the rEvo rebreather safe?

No type of rebreather can be said to be categorically safer than another. No rebreather is foolproof, and the fact remains that compared to open circuit there is a disproportionate number of rebreather fatalities, many of which have been attributed to diver error. The quality of training may be the most significant factor affecting rebreather safety. Your safety while diving is controlled by you, not by your rebreather.

Last Updated: Jan-2022

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