Can someone look over my numbers for cost of consumables on KISS mCCR and SCR?
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PfcAJ
Contributor
I just threw up a littleSo you recommend an Explorer?
Lol.
They’re cheap at least. Complete and total junk. But cheap.
They’re cheap at least. Complete and total junk. But cheap.
Agreed, but I wouldn't give up my CCR at double the opening investment. IMO, it's the only way to dive.
Absolutely.
I love mine. I don't dive very deep, I never spent a lot on helium, but it has really revitalized my interest in diving.
KevinNM
Contributor
If you are diving a CCR and paying those kind of rates you should talk to airgas, matheson and praxair about buying or renting a big tank from them. A 120 cubic foot argon fill at my local Matheson shop is $35, and argon is lot more expensive for them to produce than oxygen. Unless you use a booster you won’t be able to use a lot of it, though how much depends on your requirement for pressure. It may still be both cheaper and more convenient. But rental and fill rates vary widely (I’ve seen prices for a 340 cubic foot tank oxygen fill range from $19 to $55), as do policies on filling customer owned tanks. That’s why you should talk to all 3.
We did the math before we bought, and compared to OC at nitrox depths you basically break even on the direct costs and won't ever recover the acquisition costs. However, you will save significant money on the direct costs compared to OC when you're diving at trimix depths on CCR. In the 300 or so hours since we've pretty much verified our initial estimates.
I estimate a little more for O2 use then Tom, not so much for cost projection but for dive planning. My leaky valve flows at 0.8 lpm, but I plan for 1.25 lpm as that's what it has averaged out to over time with dil flushes in multi level cave diving, increased PPO2 for deco and O2 flushing at 20' to verify the cells are still functioning as advertised.
Over the last 3 years I've paid between $99 and $145 for a 44 pound keg of sorb, and the last couple I bought were $130 per keg, but hourly sorb costs are something of a grey area because scrubber life is itself a huge grey area as most of the published scrubber life estimates are predicated on cold water and extremely conservative O2 metabolization rates in the 3 lpm range.
The scrubber design comes into play as well. I have the normal length scrubber in my Sidekick and it holds about 5.4 pounds of 4-8 mesh and about 5.7 pounds of 8-12 mesh (but we pack very tightly and those numbers are a bit more than the KISS numbers). We slowly pushed that out to 6.5 hours (6 hours swimming about 30 minutes of deco) with 8-12 mesh, and that's as far as I want to push it in warm water and nitrox depths. In cold water (anything below 65 degrees) I scale it way back to about 3 hours to account for the less efficient reactions that occur at colder scrubber temps. At normoxic trimix depths I scale it back to around 4 hours in warm water, given the increased volume of gas getting pushed through the scrubber and the reduced dwell time in the scrubber for the reactions to occur. I also scale the planned duration back about 20% with 4-8 mesh, which is sometimes less expensive.
KISS makes a slightly larger scrubber (about an inch longer) that would hold more sorb, but the problem is that you'll end up using more sorb every time you pack, so you end up wasting more sorb on the shorter dives. If we start needing more time on deeper dives, we might buy a larger scrubber can to use just on those dives.
Many of the CCR divers I know generally save sorb across diving days if they have only partially used a scrubber, even though I am not aware of any manufacturer or cert agency that actually recommends this. Not surprisingly the details differ widely on how it's done. I know one diver that just leaves the sorb out in the open air over night. I dry the scrubber can and water trap, and then store it in a dry bag to keep the moisture content constant. After encountering several other divers who did it, I did store sorb with just an hour or two on it from weekend to the following weekend a couple times, but I did that in no deco OW conditions where bailout to the surface was an option. I also take care to ensure the sorb hasn't been flooded, etc and take care to ensure it isn't dropped subjected to excessive vibrations, in order to avoid the potential for channeling. I don't recommend the practice however as there are a lot of variables involved, you're pretty much your own crash test dummy, and it's not something I'd consider at all diving in a cave or soft overhead environment.
(Many of the Spirit and Sidewinder divers change out half the scrubber after a short dive on the basis that the first scrubber in line theoretically takes out most or all of the CO2 and the second scrubber does very little or nothing. Personally, I would not try that on a deep dive or a hard working dive where high mass flow through the scrubber and reduced dwell time may result in the second scrubber doing half the work.)
In some cases however even saving partially used sorb over night isn't practical. For example, if I arrive in N FL on a Friday afternoon and get in a 1.5 to 2.0 hour warm up dive, I've now only got 4 to 4.5 hours left on the scrubber (shallow, warm water conditions). That puts me right on the edge of my comfort zone if I do a single 4 hour dive the next day. If I do a pair of 3 hour dives, I'm now forced to re-pack between dives 1 and 2 - and I've created the same potential problem for Sunday's dive(s). It's quite often just not worth it - sorb is cheap compared to dying, and repacking often just makes things a lot easier and avoids the need to track scrubber use and dive conditions from day to day.
All in all I probably average 4 hours on 5.7 pounds of pounds of scrubber, so 1.4 pounds per hour, 31 hours per keg - or about $4.70 per hour at $145 per keg.
Now, there are other costs that do or can occur. Sensors run around ($90 each and even with just 3 that's still a $360 start up cost (since it's nice to have a spare). I tend to replace my sensors annually, including the spare which is almost always used during the year, and I've averaged around $200 per year, due to getting good deals on sensors at DEMA.
We live in an area of NC where getting a 3000 psi fill of O2 is a challenge and where getting O2 at all could sometimes be a problem. I ended up searching for a good deal on a Haskel AG-30 (which was still around $1000 once everything was said and done, doing the rebuild and O2 cleaning myself). I also got decent deals on a pair of K bottles filled with O2 and a T bottle for helium - but again that ended up being another $500 total. It will pay for itself - eventually - largely because the local dive shop charges $1 per cubic foot for O2, when they have it.
Consequently, your hourly costs will depend on the unit you have, the dives you do, how much you pay for sensors and how you choose to manage the sorb duration. I strongly recommend you stay with the recommended duration and slowly push that out very slowly over time, in controlled, open water conditions and while keeping good data on work load, water temp, O2 use on the dive, etc.
I estimate a little more for O2 use then Tom, not so much for cost projection but for dive planning. My leaky valve flows at 0.8 lpm, but I plan for 1.25 lpm as that's what it has averaged out to over time with dil flushes in multi level cave diving, increased PPO2 for deco and O2 flushing at 20' to verify the cells are still functioning as advertised.
Over the last 3 years I've paid between $99 and $145 for a 44 pound keg of sorb, and the last couple I bought were $130 per keg, but hourly sorb costs are something of a grey area because scrubber life is itself a huge grey area as most of the published scrubber life estimates are predicated on cold water and extremely conservative O2 metabolization rates in the 3 lpm range.
The scrubber design comes into play as well. I have the normal length scrubber in my Sidekick and it holds about 5.4 pounds of 4-8 mesh and about 5.7 pounds of 8-12 mesh (but we pack very tightly and those numbers are a bit more than the KISS numbers). We slowly pushed that out to 6.5 hours (6 hours swimming about 30 minutes of deco) with 8-12 mesh, and that's as far as I want to push it in warm water and nitrox depths. In cold water (anything below 65 degrees) I scale it way back to about 3 hours to account for the less efficient reactions that occur at colder scrubber temps. At normoxic trimix depths I scale it back to around 4 hours in warm water, given the increased volume of gas getting pushed through the scrubber and the reduced dwell time in the scrubber for the reactions to occur. I also scale the planned duration back about 20% with 4-8 mesh, which is sometimes less expensive.
KISS makes a slightly larger scrubber (about an inch longer) that would hold more sorb, but the problem is that you'll end up using more sorb every time you pack, so you end up wasting more sorb on the shorter dives. If we start needing more time on deeper dives, we might buy a larger scrubber can to use just on those dives.
Many of the CCR divers I know generally save sorb across diving days if they have only partially used a scrubber, even though I am not aware of any manufacturer or cert agency that actually recommends this. Not surprisingly the details differ widely on how it's done. I know one diver that just leaves the sorb out in the open air over night. I dry the scrubber can and water trap, and then store it in a dry bag to keep the moisture content constant. After encountering several other divers who did it, I did store sorb with just an hour or two on it from weekend to the following weekend a couple times, but I did that in no deco OW conditions where bailout to the surface was an option. I also take care to ensure the sorb hasn't been flooded, etc and take care to ensure it isn't dropped subjected to excessive vibrations, in order to avoid the potential for channeling. I don't recommend the practice however as there are a lot of variables involved, you're pretty much your own crash test dummy, and it's not something I'd consider at all diving in a cave or soft overhead environment.
(Many of the Spirit and Sidewinder divers change out half the scrubber after a short dive on the basis that the first scrubber in line theoretically takes out most or all of the CO2 and the second scrubber does very little or nothing. Personally, I would not try that on a deep dive or a hard working dive where high mass flow through the scrubber and reduced dwell time may result in the second scrubber doing half the work.)
In some cases however even saving partially used sorb over night isn't practical. For example, if I arrive in N FL on a Friday afternoon and get in a 1.5 to 2.0 hour warm up dive, I've now only got 4 to 4.5 hours left on the scrubber (shallow, warm water conditions). That puts me right on the edge of my comfort zone if I do a single 4 hour dive the next day. If I do a pair of 3 hour dives, I'm now forced to re-pack between dives 1 and 2 - and I've created the same potential problem for Sunday's dive(s). It's quite often just not worth it - sorb is cheap compared to dying, and repacking often just makes things a lot easier and avoids the need to track scrubber use and dive conditions from day to day.
All in all I probably average 4 hours on 5.7 pounds of pounds of scrubber, so 1.4 pounds per hour, 31 hours per keg - or about $4.70 per hour at $145 per keg.
Now, there are other costs that do or can occur. Sensors run around ($90 each and even with just 3 that's still a $360 start up cost (since it's nice to have a spare). I tend to replace my sensors annually, including the spare which is almost always used during the year, and I've averaged around $200 per year, due to getting good deals on sensors at DEMA.
We live in an area of NC where getting a 3000 psi fill of O2 is a challenge and where getting O2 at all could sometimes be a problem. I ended up searching for a good deal on a Haskel AG-30 (which was still around $1000 once everything was said and done, doing the rebuild and O2 cleaning myself). I also got decent deals on a pair of K bottles filled with O2 and a T bottle for helium - but again that ended up being another $500 total. It will pay for itself - eventually - largely because the local dive shop charges $1 per cubic foot for O2, when they have it.
Consequently, your hourly costs will depend on the unit you have, the dives you do, how much you pay for sensors and how you choose to manage the sorb duration. I strongly recommend you stay with the recommended duration and slowly push that out very slowly over time, in controlled, open water conditions and while keeping good data on work load, water temp, O2 use on the dive, etc.
I think there are some shallower dives where a CCR makes sense from a safety standpoint. Yeah, I can't believe I wrote that either.
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I think that @doctormike was saying you only have a financial ROI on a CCR when diving helium, i.e. it will only save you enough money to pay for itself. Sounded like he was also implying that there are other reasons that it would make sense to use them, just not financial sense.
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