The ISC Megalodon CCR or more fondly called “The Meg” is a CCR system that has been embraced by divers of all skill levels around the world. Meg divers dive from 60fsw to over 742 fsw/225 msw. With its versatility of design, it can be configured to meet any level of diving and keep pace with the “Meg divers” skill levels.
Fundamentally the Meg was designed for the most demanding dives with consideration for the diver and their needs. Addressing not only the basic requirements of performance that a true 3rd party tested CCR must undergo, but also the other considerations that is not considered, such as travel concerns and conducting repairs in remote locations.
The design of the Meg meets fundamental design requirements established by the creator Leon Scamahorn, Founder and CEO of InnerSpace Systems Corp, in the USA. InnerSpace Systems is an ISO 9001:2008 registered company and the only one like it in the USA at this time. ISC is a custom CCR manufacturing company that designs systems to meet customer requirements.
To understand the Meg the reader must understand what a well designed CCR should be able to do and we can start with design considerations.
- Robustness: CCR construction consideration for the Meg was that the unit should feel like a piece of military hardware and that the customer can use it without fear of a failure under serious conditions and with minimal maintenance other than the “Pre-Dive Check List” that Meg users are trained to use. The unit should not feel like a toy that the user must baby and fear damaging something that will keep them out of the water especially on a dive trip.
- Redundancy: The Meg electronics supports 2 truly independent electronic oxygen monitoring systems with 2 independent displays telling the diver what they are breathing at all times. A failure of one system will not affect the other as there is no commonality between the 2 systems; this includes the operation of the automatic oxygen injection system. The system brain operates the oxygen injection system independent of the primary display, but the primary display adjusts set points and indicates PO2 and system status for the system brain. The secondary offers only monitoring and the diver’s heads up display (HUD). Each system has its own voting logic for oxygen cell monitoring. The brains of the oxygen injection, primary display and the secondary monitoring system is protected in a soft potted machined enclosure and further protected inside a ¼ inch thick 6061 T-6 anodized aluminum housing and they are independent from the handsets that only display the data to the diver. The brains of the system being isolated from the two displays protects it from failure as the Meg’s electronics can have both displays flood and the oxygen injection system will not be effected nor will the HUD as it will still operate offering the diver all 3 oxygen cell data. ISC does not believe the CCR systems controllers should be in the handsets as this does not provide adequate electronic system redundancy. The electronics system also can display full time to the diver the electrical output of the oxygen sensors, showing real time data to the diver and the diver can actually dive the system that way instead of the displayed PO2. This method does not require system calibration like the displayed PO2 on the displays. The voting logic is another unique system that each redundant electronic system shares. A sensor or sensors can be voted out if outside parameters. The system can actually maintain the oxygen set point off of one good sensor and this is confirmed by the diver using the displayed millivolt (mV) output on the system monitor page on both handsets. The advanced design of the APECS platform allows for customization of the electronics to meet the customer’s needs such as the APECS electronic cards can be swapped to different sides if the diver wants to have the primary display on the right wrist. With that being the simplest modification, the most extreme is to have two independent solenoids operated by two independent oxygen injection systems and displays. The diver can have the ultimate system. The APECS even allows for ISC approved dive computers to be added to the system for onboard decompression monitoring. Other systems such as the manual oxygen injection and diluent injections systems are either lung demand or physical push button and they may be used by the diver at anytime to over ride the electronics if a too high or too low oxygen condition exists. Other gases may be used or plugged into the breathing loop if the diver runs out of primary gases.
- Reliability: CCR systems can be subjected to very demanding conditions in the field and by the diver. This takes the best of materials to withstand punishment dished out by the conditions. The materials that the Meg uses is a 6060 T-6 anodized aluminum the same material that aluminum SCUBA cylinders are made from and the plastic the Meg uses is machined copolymer acetyl. All materials are not just provided by just any provider but called out on the specs for the building of the Meg and only the best materials are used. The diver does not wish to have their CCR system “fall apart” underwater or during a vacation thus costing them their trip and fun. The CCR you dive should be tough enough to be used in a reasonable fashion with moments of high demand, and availability of high levels of care for the unit is not an option at this time. You also want the unit to perform consistently the same as if it was new out of the box years later other than the regular wear and tear of solid use.
- Recoverability: The CCR diver has many issues to address during a dive and one of the worse is a system flood that would contribute to a “Caustic Cocktail” to the diver. This event must be avoided with systems in place to protect the diver from this major event. The Meg has many water trapping and water and gas expelling design features. The first one is water expulsion from the exhaust side counter lung. If the diver loses their Dive/Surface Valve (DSV) from their mouth then water will move to the exhaust counter lung and the Meg diver can expel the water from the exhalation counter lung thus preventing water from moving to the scrubber canister area. The Meg also has a water trap inside the gas plenum canister that houses the CO2 scrubber canister and traps water from moving to the diver. The breathing hose assembly also has two water traps that move the water from any point in the loop to the counter lungs thus insuring the diver does not breathe in a caustic mix. The Oxygen sensors are also between the diver and scrubber canister, this allows the O2 sensors to act like a water sensor if a caustic solution is moving to the inhale side of the breathing loop giving the diver a early detection to transition off of the breathing loop and on to a alternate breathing system (ABS). The Meg may also be fitted with a water tolerant CO2 canister that will prevent any water touching the CO2 absorbent material at all. This is a bit of overkill as the breathing loop design will itself protect the diver and give an obvious indication of potential flood giving the diver time to bail out to another system. CCR systems that do not have an over the shoulder counter lung design or do not have adequate water trapping or water expulsion system are prone to give the diver a caustic cocktail with little or no warning.
- Regulation: Rebreather’s that are marketed in Europe must fall into the EN 14143 standard. As of yet, the Meg is not rated, but ISC is expected to have the Meg rated by the end of the 2010. CCR systems must be held up to a standard and EN 14143:2003 or the new 14143:2010, is a place to start and promotes quality of the CCR system, the other standard or “guidelines is the U.S. Navy 01-94 Unmanned test methods in which the Meg has successfully passed and beat the U.S. Navy MK-16 in performance. The Meg even passed tests that are not yet written. The Megs performance was so good that 01-94 will be rewritten. The Megalodon and the APECS 2.5/2.7 has been 3rd party tested by the U.S. Navy, the HSE lab, ANSTI, and Dive lab. No other CCR manufacturer can say that.
- Repair: The Meg is designed to be easily repaired by not only the factory but by the customer that has been trained by ISC to do all major repairs. ISC provides the opportunity for all customers to participate in the training an actually build their own Meg and demystify the CCR itself. Major film crews use the Meg as they can repair the unit on the spot if it was damaged during an action shoot. The Meg component design lets you replace components without having to ship it back to the factory or be charged for a major overhaul or replacement of the electronics head assembly as other designs allow, for something simple such as a failed solenoid that may be potted and unreachable for replacement. In the event of a major repair of the Meg, ISC has repair techs in Europe and Asia that can repair and test the system as if it was sent back to ISC.
- Remote travel: The Meg packs easily into the overhead so the diver may carry the Meg with them and observe the inspection agent scrutinizing the Meg if necessary, this is better than having an agent look at it and damage the unit before it goes under the airplane. The Meg may also use any size cylinders and you may use any size that you want at your dive destination or you may plumb into your out board cylinders instead of using two back mounted cylinders.
- Product Improvement: ISC applies the same design considerations into all of its products to give the diver the best buy for the money with extremely high quality. ISC wants all of our customers to enjoy all our CCR systems. All ISC systems are upgradable to the latest electronics and other new subsystems as ISC product improvement develops.
- Survivability: Taking the above design into account an example of complete systematic failures induced by number unrealistic fictional factors, the reader can understand what the Meg/APECS system can do in such a extreme situation. The Meg can have the following failures and the diver can complete the dive mission without harm.
The situation is a diver is at 330 fsw/100 msw at a water temperature of 28°F/-2.22°C on a saturation dive using a 8lb/3.62kg radial scrubber and he has used 3 of the 5 hours with two remaining. His work effort is equivalent to a 1.35 lpm Co2 Combat swim pace.
- Primary and automatic injection system failure. Diver can inject oxygen manually.
- Flooded Secondary handset, secondary battery below 4.8 volts. HUD is operational displaying single operating sensor and alarming on the two bad sensors.
- Two oxygen sensor failures, but one sensor is still operational. Set point can still be maintained.
- Leaking KOH from sensors into exhaust side of breathing loop not inhales side.
- 1/3rd of exhale counter lung was removed leading to a partial breathing loop flood, but loop is still functional as is scrubber. No fear of caustic cocktail due to water traps.
- Loss of onboard gases. Diver plugs into external sources.
- Loss of ADV and isolator.
Looking at the Meg and its design, the Meg diver may use a variety of subsystems that will meet their needs for a desired dive. The Meg may be used with a variety of CO2 scrubber systems, cylinders, back plates, BC’s, and harnesses. The diver may also elect to buy the Meg from ISC under a variety of configurations and save themselves’ money if they already own various components. The Meg is a diver’s diver rebreather and it truly sets the standard for quality and functionality in the diver’s kit.