MX Series - mCCR Rebreather
Quick Overview
MX HH Explorer mCCR Rebreather
Purpose: OpenOceanDiving/ Wreck Diving
Manufacturer: Custom HH Rebreather Designed by UTD
BackGas Bailout/Dilute:Single Isolated manifold on twin40's/6L or bigger
HH CO2 Canister: Std Length Canister with 7.8lbradial scrubber
Water Trap: Yes
Breathing Loop: Bail Out Valve (BOV)
HamerHead (HH) Head andElectronics
O2 Sensors: 3 Teledyne R22D
Counter Lung: Back Mounted
Off Board O2 :
- Recreational Dives-6cft/170l no Bailout needed
- Technical Dives -40cf/1132Lfor Supply and Bailout 2nd stage on O2 supply has an on/off isolator
- Trimix Dives - 40cf/1132 ofO2 and Nitrox 50 Supply and Bailout (For divesbelow 160/48m -240’/)72m):
PPO2 Monitoring Handsets with LCD:
- Primary PPO2 Handset with LCD Display
- Secondary PPO2 Handset with LCD (Left Side) and Heads Up Display(HUD)
Gas Injection System:
- Left side Oxygen Addition block with QC6 Female wet pluggable
- Righ tside Diluent Addition block with isolator shutoff and QC6 Female wet pluggable
- O2 and other deco bottle has male QC6 Hot Swappable
MX HH Expedition mCCR Rebreather
Purpose:Cave/Extreme Multilevel Diving
Manufacturer: CustomHH Rebreather Designed by UTD
BackGas Bailout/Dilute: Dual Isolated Manifold forTwin80's/11L or larger tanks & a Stage Gas Diluent (Optionalforlong dives) : 80cf/ 2200L
HH CO2 Canister: Long Canister with 7.8lb radial
Water Trap: Yes
Breathing Loop: Bail Out Valve (BOV)
HamerHead(HH) Head and Electronics
O2 Sensors: 3 Teledyne R22D
Counter Lung: Back Mounted
Off Board O2 :
- Recreational Dives-6cft/170l no Bailout needed
- Technical Dives -40cf/1132Lfor Supply and Bailout 2nd stage on O2 supply has a withIsolatoron/off
- TrimixDives - 40cf/1132 ofO2 and Nitrox 50 Supply and Bailout (For divesbelow 160/48m -240’/)72m):
PPO2 MonitoringHandsetswith LCD:
- PrimaryPPO2 Handset is aFischer Cable for alt manufacturers computer andPPO2meter
- Secondary PPO2 HandsetwithLCD (Left Side) and Heads UpDisplay(HUD)
GasInjectionSystem:
- LeftsideOxygen Addition block with QC6 Femalewetpluggable
- Rightside Diluent Additionblock with isolator shutoff and QC6 Femalewetpluggable
- O2andother deco bottle has male QC6 HotSwappable
MX KISS Expedition mCCR Rebreather
Purpose: Ocean/Cave/ExtremeMultilevel Diving
Manufacturer: CustomKISS Rebreather Designed by UTD
BackGas Bailout/Dilute: Dual Isolated Manifold forTwin80's/11L or larger tanks & a Stage Gas Diluent (Optionalfor long dives) : 80cf/ 2200L
KISS CO2 Canister: Canister with 5.5lb C0-Axial
Water Trap: Yes
Breathing Loop: Bail Out Valve (BOV)
KISS Headand Shearwater Electronics
O2 Sensors: 3 AI R22D
Counter Lung: Back Mounted
Off Board O2 :
- Recreational Dives-6cft/170l no Bailout needed
- Technical Dives -40cf/1132Lfor Supply and Bailout 2nd stage on O2 supply has a withIsolatoron/off
- TrimixDives - 40cf/1132 ofO2 and Nitrox 50 Supply and Bailout (For divesbelow 160/48m -240’/)72m):
PPO2 MonitoringHandsetswith LCD:
- Primary PPO2 Shearwater Handset is a hard wiredOLED PPO2 meter (Predator with no Deco Software)with integrated Depth and Time and DiveLogging
- Secondary PPO2 ShearwaterHeads Up Display(HUD)
GasInjection System:
- LeftsideOxygen Addition block with QC6 Femalewetpluggable
- Rightside Diluent Additionblock with isolator shutoff and QC6 Female wetpluggable
- O2 andother deco bottle has male QC6 HotSwappable
For more Images of the MX KISS Rebreather Configuration Click Here
Introduction
Welcome tothe MXSeries Manual Closed Circuit Rebreather (mCCR). This document isintended to cover the various details of the MX Series rebreatherconfiguration and its individual components. In order to completelycomprehend the concept and design behind UTD’s MX series rebreatherconfiguration, one must first understand the 10 covenants of UTDwith our roots in the DIR/Hogarthian configuration and divingphilosophy. Following that we will discuss the overall designphilosophy and how it integrates into diving within a mixedconfiguration UTD team, finally covering the A to Z’s of the MXSeries configuration.
10 CovenantsofUTD
1. Minimalist approach -Onlytake what you need and is necessary for the dive.
2.Holistic - All componentsof the system are thought out, work together and have a solidreason behind their use and placement.
3.Standardized mixes - Allgases provide the desired PPO2 at the target average depth of thedive and the deco, as well as keep the equivalent narcosis depth of100’/30m or less. NO DEEP AIR.
4.Streamlined and accessibleequipment configuration - All components should be stowed away yetconvenient to access. This reduces drag and entanglement hazardsyet allows easy use and re-stowing.
5. Gasmanagement - Enough gas to bring your buddy and yourself, in anemergency, to the next available gas source, whether it be thesurface, a deco bottle, or stage bottle.
6.Consistent yet modularequipment configuration - An equipment configuration that is notonly minimal in approach, but consistent, modular and scalablewithin the team for all types of diving and divingenvironments.
7.Thinking Team - No teammember should ever turn off their brain andrely on another personor piece of equipment to make the “sole”decisions - NO “trust me”dives.
8.Unified Team approach -the team is your backup - gas, equipmentandbrain.
9.Theproper training and experience for the dive - One should taketheappropriate classes to ensure consistent protocols and skillsforthe dives, and must understand the potential hazards. Thiswillensure the correct starting point tobuildexperience.
10.Situational awareness -Manage the environment, equipment and teamgiving equal attention toeach. Never become fixated or inflexible.Keep your head up, eyesopen and brain on.
Background &DesignPhilosophy
The MX series is a"true" mCCR rebreather, in that nothing adds gas to the loop withoutthe diver's input. It is the next generation of rebreathers designedby UTD to incorporate the best of both UTD/DIR and CCR worlds;it takes the advantages and simplicity of the mCCR world andthe advantages and consistent configuration from the UTD/DIR world.To understand the configuration one must understand that weare integrating (merging) two full diving systems – UTD/DIR andmCCR diving. We then dive the mCCR as the primary system andcapitalizeon its advantages while preserving the safety and gasmanagement philosophy inherent to the UTD/DIR philosophy as thebailout or secondary system. In both cases we use Ratio Deco asthe decompression strategy. We use rock bottom in thebackgas/diluent filled with standardized gases and we usestandardized decompression gases for the open circuit bailoutduring decompression. We average our PPO2 of the mCCR at 1.0 orhigher, ultimately shooting for a constant PPO2 of 1.2 on theshorter dives and driving down from there as the dives becomelonger. This will allow some variance when utilizing RatioDeco.
Ultimately we keep the divingand training philosophy of UTD and incorporate the skill set fromUTD open circuit diving. This makes it consistent with previoustraining, philosophy, skill set and ultimately compatible with otherUTD/DIR mCCR rebreathers divers, along with otherUTD/DIR SemiClosed Rebreather divers and other UTD/DIR OpenCircuitDivers.
The acronym mCCR standsfor manual closed circuit rebreather. With the MX series we aretruly a manual gas addition system – no Constant Oxygen PressureInjectionSystem (COPIS), or leaky valve. We evolved to this absolute manual system as we felt thatan electronic gas addition system, such as solenoids controlledby electronics, did not fit with our philosophy. As far as a COPISor leaky valve "style" O2 addition system, we found that becauseofthe wide variety of metabolic rates during the different workloads of a typical dive and because of the constant depth changes adiver encounters, using a fixed flow rate of O2 to compensate forPPO2 drop in the loop was not advantageous. Keeping the desiredPPO2 value throughout the various stages of a dive requires anequal amount of monitoring and adjustments with or without the COPISor leaky valve. The inability of the COPIS or leaky valveto accurately add enough O2 to compensate for metabolism ordepth changes, as well as the depth restriction of unit, theconstant buoyancy changes it creates, the risk of O2 spiking atdepth, the false sense of security to the diver in that one maythink it is a "safety net," which it in reality it’s not, and theincreased task loading it potential creates when off the loop allout weighed any benefits a diver may perceive they are receiving.Constant awareness and manual adjustments to the PPO2 from the diverare still required at ALL times and therefore, following theUTD/DIR principle of only taking what you need and eliminatingunnecessary risk, we eliminated the COPIS/Leaky Valve fromour configuration.
The way we configureour system, is to use standardized bottom mixes as bailout and diland at max depth this has a PPO2 of 1.2. Therefore a traditional"dilflush" if an O2 spike is created by the COPIS or leaky valveis difficult. By eliminating this constant bleeding of O2 intothe system, it is much easier to manage the system and reduces ourriskof O2 spikes. Essentially, we need to add very little O2 atmax diving depth to compensate for PPO2 drop, as the Diluent we addis generally above 1.0. On a typical dive the changes in depthand inconsistencies in the diver interface (clearing a mask)requires that the diver add additional gas to the loop. That gasis generally Diluent which is within the correct PPO2 range (atmax depth) therefore requiring very littleO2 addition.
The argument that theCOPIS or leaky valve is safer as it is a "safety net" is trulyinvalid in our opinion as this so called "Safety Net" is can neveraccurately predict you O2 needs and therefore by definition it isreally not a"safety net" but a false sense ofsecurity.
The beauty and design ofthe MX series configuration is just how well each component isthoughtout. Each and every piece of equipment has a purpose (if nottwo), place and backup. For example, if you O2 injector was tofail closed, you would simply plug the O2 into the diluent injector.Or if you were to lose your right post and could not add diluentvia the injector, you can simply add diluent from the BOV. Allaspects and bailout modes have being deliberately thought out tobe holistic, consistent and compatible, down to the reason wewear standardized UTD/DIR mixes on our back (bailout/diluent) anddecobottles in standard OC UTD/DIR configuration. This isimportant because it serves a dual purpose: Number 1, if the PPO2handsets orO2 sensors are faulty, wet or damaged and theelectronics system have failed, the MX Series can then be used in anidentical fashion to the UTD/DIR PSCR’s or Passive Semi ClosedCircuit Rebreathers manner. It will extend your bailout backgas anddeco gases to an 8 to 1 ratio while exiting in that emergency.Number 2 if the rebreather is flooded or unusable, one could justsimply bailout to full Open circuit and go home. So the backgas anddeco gases serve us to do PSCR or OC bailout if needed. As I saidevery piece of equipment has a purpose , place andbackup.
FieldTesting
***********Iwant to be clear that this was only a test and not how we dive. Wedo not recommend you dive the unit like this. This was only a test.******************************
I was doing a series of testswith this idea and wanted to find out the PPO2 drop in 5 minuteincrements without adding any additional O2 or Diluent. Just simplygo to a specific depth and set the PPO2 to 1.0 or 1.2 or 1.4 andthen just stay either stationary at that depth or kick lightly oreven work hard. The idea was to simulate what would happen, assuminga constant depth, if the diver was to be distracted and did not addO2 or adjust PPO2. How much would the PPO2 drop and how long wouldit take to become hypoxic?
So in my test I found that ifI am stationary, the PPO2 will drop 0.2 every five minutes,for light work load I found a PPO2 drop of 0.25, a heavy work loada drop of 0.3. If I am at a constant depth and the PPO2 is set at1.0 or above and I become distracted and am working hard we wouldget this:
1.0. @.0mins
0.7. @5mins
0.4. @10mins
0.1 @ 15 mins orpotential hypoxia
The interesting part isthat I was unable to sustain a workload for 5 minutes to get it todrop more than 0.35. What I found was that after 5 minutes,without adding any additional O2 or Diluent, the breathing loopvolume had become so diminished due to the O2 metabolism that itbecome very difficult to breath, and by 7 minutes into the test itwas impossible to breathe and by 8 minutes I had to bailout toopencircuit because I could not breath the loop. In other words,I would run out of loop volume before significant or dangerouslevels of PPO2 drop. This volume depletion is essentially an "alarm"of sorts that warns the diver that additional gas is needed. AddingO2 would both return the loop volume and the PPO2. Keep in mind wedo dive standardized gases on the diluent side, and thesestandards gases average a PPO2 o 1.2 at depth, so if the diversimply added dil at depth the PPO2 would still be very close to 1.0or above.Hence the advantage of using standardized mixesasdiluent.
DivingMixedTeams
The first rebreather tobe introduced to the DIR community was the Halcyon pSCRRebreather,which we affectionately termed "the fridge,” and thenlater, around 2001, we started using the pSCR - RB80. Now, almost 8years later,we have moved to fully closed circuit systems or mCCR(manual closed circuit rebreather) which we called the MC90 Series when usingthe“copis” or leaky valve and the new MX Series without “copis”or leaky valve.
But regardless of whichunit we dive, we have stuck to the core principles of UTD/DIR-consistency within the team (and community) of bailout volumeand logistics, standardized gases for bottom gas and deco,Ratio Decompression strategies, matched equipment configuration,skill procedures for out-of-gas and valve failures, andso on.
The rebreathers (pscr's,and the mccr - mc/mx configurations) are simply a classicDIR/UTD technical configuration (a set of doubles and deco bottlesas needed) wrapped around the rebreather which syphons off atiny amount of the OC gas for use in the CCR but leaves the majorityofthe OC gas for bailout. Keep in mind that both the pSCR andthem CCR add gas (either O2 or Dil) manually - there is nothing onthe system that adds any gas without you wanting to. Meaning thereis no solenoid, no electronicsor other things that could unintentionally add gas withoutyour knowledge. It is simply a CO2 canister, counter lung, breatherloop and so on with O2 sensors to measure the PPO2. As a side note:UTD does require an O2 sensor on all rebreatherconfigurations including any pSCR system such as the RB80 or RB2000and others.
So here are a few things thatare important for an OC buddy when diving in the mixed team withpscr and/mccr diver. These apply specifically when diving with adiver using the MC or MX fully closed systems :
1. It's important that aRB diver is always moving around slightly so you know they arealive, as there won't be bubbles to confirmbreathing.
2. In emergencies, suchasCO2 hits, valve failures or out of gas situations, the RBdiver immediately bails out from the CC to OC by simply flipping theBOV to open circuit. This happens by moving the lever on thebailout valve to the down position, which opens the "necklace"regulator on the bail out valve (BOV). Now the bailed out RB diveris on the backup reg on the left post, just like a standard set ofdoubles, and both divers in a mixed team are on open circuit. Thebackgas is a UTD standard gas and is always breathable at any pointin the dive. This bailout procedure eliminates the need for the CCdiver to monitor the rebreather while dealing with the emergency.The CC diver can now give full and undivided attention to theemergency. As we carry ample bailout this is not consideredproblematic from agas management perspective and because thebailout valve is simple and easy to access it and will be easy toreturn to CC once the emergency is dealt with. We propagate themessage of "when indoubt, bailout."
A side tangent : Themessage propagated in other circles of the ccr diving world ofstaying on the rebreather at all costs while dealing with anemergency is massively problematic, as the CC diver can potentiallystop monitoring the rebreather while dealing with the emergencyand therefore may create a very dangerous situation. Even ifthe electronics are only there as a backup they too could fail asthey are not in use at all times.
The reason this messageof staying on the CC while dealing with emergencies was propagatedis because number one, many ccr divers do not personallycarry sufficient bailout volumes to handle an emergency in OC mode(they try to divide the bailout for one person between team membersor just simply go alpinistic style - no bailout at all) andsecondly because their bailout configuration is so massivelyconvoluted and/or difficult to donate or restore to it's originalstate that once deployed and the emergency is dealt with, returningto CC canbe a massive pain in the butt, so they simply just try tostay on the unit while dealing with the emergency.
An example I have seenis carrying the bailout in a stage bottle which forces one to selecta bottle, pull the regulator from the stage bottle bungee,remember to turn it on and then bailout to deal with the emergency,then once dealt with try to return the regulator to it'soriginal position. It reminds me of the "pre" DIR days when we wouldstuff the long hose into a bungee and would have to pull it out ofthe bungee to donate, then it was such a hassle to return tothe bungee. So we would not bother practicing s-drills because itwas too much trouble to put the long hose away. Hence theHogarthian system was born to simply wrap the long hose back aroundyour neck,which has now become the standard method of UTD/DIR longhose configuration.
But, back tomixedteams:
3. If an OC teammateneeds gas, the CC diver switches to OC by moving the lever on thebailout valve, unclips the long hose, lifts the loop out of theway,donates the long hose, and stays on OPEN CIRCUIT. Now bothdivers are on OC, problems can be sorted out, then the RB diver cango back to CC. We put the CC diver on open circuit during anemergency so there is no need to manage the rebreather andthe PPO2.
4. If an OOG diver grabsthe regulator off the O2 bottle in an emergency, the regulator hasan isolator at the second stage, so essentially the gun is notloaded- although the bottle is on and feeding the RB, the secondstage is off, so it takes two steps to breathe pure O2. There's anoverpressure relief valve on the O2 first stage so the second stagecan be isolated safely. At recreational depths, there often won't bea second stage on the O2 bottle, since the only time it would beused is for emergency O2 deco.
5. Cautions that OC divers ina mixed team should know about:
Prevent the systemfrom flooding by not taking the loop out of the mouth unless the BOVis set for open circuit.
Floods make the righeavy,but the wing should provide enough lift to bring the diver tothe surface in neutral buoyancy. A small amount of water in theloop can easily be cleared.
PPO2: There are twohandsets and a head-up display. The handsets are clipped to the hipd-rings of the diver, again in the DIR/UTD thought process, rightprimary and left backup. The units are always monitoring the PPO2,however the display may turn off in power save mode - pressing anybutton on the handset will turn on the display. Both handsetsdisplay the individual PPO2's from each of the three sensors on themainscreen. Each handset is independent of the other so if theprimary or secondary were to fail you would havetheother.
The head up display, orHUD,is connected to the primary handset so the diver canconveniently read the PPO2, since the displays are clipped to thehip d-rings.The HUD simply flashes an LED light with threedifferent colors.green good, red not so good and amber almost good:). They flash a sequence for each sensor (so a cycle of three setsof flashes). So for the PPO2 of 1.0 is one amber flash per sensor-flash-pause-flash-pause-flash-pause, then a longish pausedbetween the set. There is one additional flash of green light forevery tenth higher, and one additional flash of red lights forevery tenth lower.
So PPO2 of 1.2 is twogreen flashes, two green flashes, two green flashes, pause, thentwo green flashes, etc.
PPO2 of .7 is threered flashes, three red, three red, pause, etc.
PPO2 of .5 or lessis constant red flashing.
PPO2 of 1.5 or higheris constant green flashing.
6.Injector failures:
Dil injectorsticks open...isolate the injector using the omni swivel isolator atthe injector hose...this stops the flow of dil into the unit butleaves the right post open to donate. If isolated, dil gets added tothe system by taking a breath from OC and blowing it intothe loop.
O2 injectorsticks open...shut down the O2 bottle. Feather the valve to injectO2 or plug O2 into the diluent side, isolate diluent as above anduse Diluent injector to add O2 to the system while using abovemethod of cc to oc to add dil when needed.
That's about it. There isno solenoid to fail, three O2 sensors all workinginparallel...it's actually pretty simple.
Lets take a look atsome video’s of the configuration.
The A to Z of UTD’s MX HH Series mCCR Rebreather -ClickHere todownloadPDF
A. Manifolded DiluentSupply & Bailout Back Gas.
B. Right Post
C. Left Post
D. Exploration Manifoldw/ Isolator
E. Offboard O2 and/or Bailout Deco Tank
F. CCR Loopw/ built in water trap
G. Bailout Open Circuit Valve or BOV
H. O2 Injection block and Inlet with female QC6
I. Split Back Mounted Counter Lungs -Inhalation/Exhalation(right/left)
J. Over Pressure Valve (OPV) on the Exhalation Counter lung
K. Diluent gas addition block with female QC6
L. Adjustable position Heads Up Display (HUD)
M. Primary PPO2Monitoring system with LCD Handset.
N. Secondary PPO2 Monitoring system with LCD Handset
O. Open Circuit Bailout on a 7ft/2m Long Hose for donatingto Buddy.
P. Isolator Shutofffor the Diluent Feed
Q. O2 second stage regulator Isolator shutoff
R. Head and O2 sensors
S. Diluent feed - Connected to right post
T. BOV/OC2nd stage feed - Connected to the Left post
U. Radial CO2cartridge, spacer/water trap and Canister
V. SPG forDiluent/Bailout backgas
W. SPG forO2 Supply/Bailout Deco
X. Over Pressure for O2 first stage
Y. Exploration tankbands
Z. Standard UTD/DIR backplate, harness and wing
For more Images of the MX KISS Rebreather Configuration Click Here
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