Quick question about KISS Classic

[reefrat]

This sounds like a great unit but I've read several references to the "Work Of Breathing" not being so good due to the back mounted position of the counter lungs, especially compared to the over the shoulder type.
This makes sense to me but my question is- how much of an issue is it?

Being currently an OC user I regard the WOB of a regulator as a critical performance indicator right behind relaibility and safety. A regulator that dosen't breath well would be generally regarded as low performance and would not sell well regardless of how reliable it was!

So, is the WOB with a KISS classic an annoyance?
Is it a potential safety issue if you find yourself having to swim against a current for any distance at depth?

PS. I'll try not to ask too many inane questions over the next few months as I try to get a handle on the whole CCR thing- thanks in advance for you help!

 

[Warren_L]

While I do not own a KISS nor have I dove one before, I can partly answer some of your questions. I dive an Evolution myself, which has the shoulder mounted lungs, which are at the same depth as my lungs when diving. I find the WOB not to be an issue, in fact I didn't really notice it when I first started diving the unit when I switched over from open circuit.

But with back mounted lungs, you may have some difference in WOB between your inhale and exhale due to the different depths of your lungs and counter lungs. With your lungs lower, inhalation may be a bit more difficult than exhalation, which may be a bit easier due to the slight pressure differences. As you exhale, the higher pressure on your lungs and lower pressure on the counterlungs may make the gas flow a bit easier than when inhaling, which draws gas from the counterlungs down towards your lungs. Remember that in a CCR loop, you have to physically push the gas through the loop, which requires work. The other factor to consider also which may affect WOB is the scrubber canister design and the type of scrubber you use, and how you've packed the scrubber, so WOB is not solely determined by the position of the counterlungs. Radial and axial canisters are probably the more common types, each with their advantages and disadvantages. Higher mesh scrubber (smaller granules) can absorb more CO2 but can increase WOB, and of course how you pack it. Improperly packed scrubber can increase WOB also. Much to consider.

That said, however, I know several KISS divers and they all love their units, and have no issues with WOB.

 

[caveseeker7]

Jack Kellon wrote a good article on Work of Breathing, but I can't find it online.
Kevin Gurr also covers the subject in his Rebreather Fundamentals
http://www.ccrb.co.uk/rebreatherfundamentals.html

No doubt o-t-s counterlung placement means you're off to a good start. But any restriction of the gas flow through the loop will increase the WOB. That's where the different scrubber designs come in. Radial scrubbers, at least large ones (6 lbs +) can really make a difference, as do annular axial ones (similar properties). But loop diameter, flow path, number and flexibility of check valves, additional membranes, valves and the like will factor into it.

Never dove a Classic Kiss, just the Sport Kiss, but on that unit it's not an issue as long as you're not vertical in the water column. Waiting at the surface breathing on the loop is exhausting unless you stay at an angle. I usually just don't breath off the loop there. Once in a swimming position the unit breathes quite nicely.

From feedback by people that have used both Jetsams, the vertical position is less of an issue (hydrostatic WOB) while the overall WOB is higher. Judging by the amount of units in use it can't be an issue, though, once you find the best position.

 

[Mr.X]

Ditto with Caveseeker on the KISS. Overall, it is not a huge effort, but if you are going to do some heavy duty work where you might end up panting I would consider models with the least amount of resistance. The article mentioned by Caveseeker discusses something called the "Centroid" which is an "ideal" geometric position of counterlungs over the divers "sweet" spot - center of lung action??? The article is sitting somewhere in my library? Quite informative from a conceptual perspective and I need to pull it out as I have forgotten some of the tenets.

From a practical perspective it's all related to variables in RB design, your physiology and the work you intend to do. I do not have any issues with the Classic, but I certainly would not use it as my main unit if I were going to do some deep, hard work where task loading is a definitive possibility. I would liken the resistance in the unit (in the hortizontal position) to breathing off a newly refurbished Mistral double hose reg. Not bad at all. Not great when you are in odd positions though! Same with OTS. Try using them upside down!


X

p.s. the easiest breather for me was a prototype Meg with soft mushroom valves and neoprene CL's. Prism was also a nice breather.

 

[caveseeker7]

Not great when you are in odd positions though! Same with OTS. Try using them upside down!

Prism was also a nice breather.

Yes they are. Pretty good even upside down.
http://www.steammachines.com/images/040529-PrsmInstrTr/040530SB-SBesierInvert.jpg

 

[reefrat]

Based on everything I've read so far I'm leaning toward a MCCR unit with a HUD.

The only factory unit that may be available is the Meg Copis- but this is an elusive option. I couldn't find any information at all on it on the ISC website.

Alternatively a KISS Classic with an aftermarket HUD fitted.

I do like the Topaz in the ECCR's. One of the few times I've dived with a CCR buddy was a guy using a Prism on the wreck of the Swan in Western Australia a few years ago.
Can't remember his name now but at the time he had just set a world record (I was told by someone else later) for cave penetration in the Cocklebiddy caves.
It was certainly interesting following him through the bowels of the wreck- you could tell he knew what he was doing in tight spaces and that prism looked good!

 

[ScottB]

Reefrat,

I have no association with ISC other than that I just ordered a COPIS Meg and I will be taking my MOD I course for it in Playa Del Carmen with Ron Micjan from the 25th of January to the 3rd of February..

Ron Micjan made the first COPIS Meg.. there is an article he wrote about it over at Rebreather World.. http://www.rebreatherworld.com/megalodon-rebreather-articles/6256-copis-megalodon.html

The September Price list has the Copis priced out at 6169 USD complete with backplate, Hogarth harness, hoses, aluminum cylinders, valves, hp guages, 1st stages, ADV, mixed gas bypass, dust caps, sensors.

A diluent isolator valve to shut down gas flow to the ADV is $45.

O-Ring kit is $35, Deluxe O-ring Kit is $85.

A replacement Long and Short breathing hose pair is $45.

Neoprene Counterlungs instead of the Cordura nylon is $330.

A head only Calibration kit is $60..

The ISC HUD listed in the price list... is not for the COPIS.. as the HUD electronics are in the Apecs hardware.. I am told they are working on an independent HUD.

Take care,

Scott

 

[caveseeker7]

Based on everything I've read so far I'm leaning toward a MCCR unit with a HUD.

That's a good decision, I believe. Either Jetsam or ISC unit should serve you well as far as build quality, customer service etc is concerned. The one thing I really miss on my Sport Kiss is a HUD like the PRISM has. Great tool to monitor the unit.

The only factory unit that may be available is the Meg Copis- but this is an elusive option. I couldn't find any information at all on it on the ISC website.

ISC isn't particulary good about updating their website. But the COPIS are out and just a phone call to ISC away. Never had problems getting someone on the phone there. Having had a chance to look at the COPIS and talk with Leon about it in Birmingham recently I must say I was impressed. I for one like it better than the APECS version (to which you can upgrade if you ever feel the need to go eCCR).
Took a couple of pictures for my NEC report if you want to check them out (link below).

Alternatively a KISS Classic with an aftermarket HUD fitted.

At said show there was also an aftermarket HUD on a Sport Kiss, as well as the prototype of DeltaP Technologies Rebreather Monitor. Have a look at the NEC 2006 Show Report. Two more options are the Shearwater GF dive computer which will add integrated deco as well as an optional HUD. The latter, like the Meg, uses the Smithers Code to actually signal the pO2 value, but uses three LEDs to do so simultaniously rather than the Meg's single LED moving through sensors sequentially.

Last but not least, Sub Sea Systems in Australia offers a pO2 monitor with optional HUD that signals below/on/above setpoint rather than the actual value, much like the PRISM's does.

For my personal taste, the Shearwater GF for primary monitoring/deco calculation with a Sub Sea Systems monitor with HUD as secondary would be a perfect, albeit expensive, option.

One of the few times I've dived with a CCR buddy was a guy using a Prism on the wreck of the Swan in Western Australia a few years ago.
Can't remember his name now but at the time he had just set a world record (I was told by someone else later) for cave penetration in the Cocklebiddy caves.

That would be Craig or Karl.

 

[Henry]

Just a heads up that both the KISS sport as well as the classic is going to have the wetplug box eventually. I believe it is going to be 3 or 4 ports. Either KISS will be able to be shipped with the VR3 triple display pendant (one comes stock), HUD and a VR3 cable to plug in to a VR3 (for real time PO2).

Kim is just working on them now so it's just a matter of time.

Side note, as a KISS diver, I don't find the WOB to be an issue at all. I've pulled on the loop pretty hard in current and have not had any issues at all.