[mempilot]

Quote: (Originally Posted by silent running)

Hi mp, the lower WOB of a typical radial due to the shorter grain boundary is reason enough to have one. The manufacturer of the Prism certainly doesn't regard a radial scrubber as bling, it's standard equipment and integral to the system design.

I respect that not all axial flow scrubbers are created equal, but the WOB on the Meg Ax is excellent, and from those that I know that go back and forth between the Ax and Rad, it has nothing to do with WOB reasons as they don't perceive the difference or advantage. It is simply a quantity thing. For some of them, it's a bling bling thing as in "I may need it some day."

I don't recall there being an axial flow scrubber for the prism since as you say, it is a integral part of the design. This does not take away the fact that other rebreathers have excellent functionality on a well designed axial scrubber that is more than sufficient for 90% of divers. Besides, we aren't talking about the Prism anyway.

Quote: (Originally Posted by silent running)

As for duration, some of us dive many days in a row in far away places where we must bring our own sorb. The increased duration which comes from a good radial allows for more diving with less travel weight and less hassel. Just returned from 2 weeks of diving in Indonesia changing sorb every other day-50 hrs from 6 fills, 1 20 kg container, even had 1 fill left over. My axial Meg diving buddy had to bring 50% more sorb, paid more in excess baggage charges and sometimes had to change his scrubber in the middle of the dive day. I'd bet he'll have a radial before his next overseas trip...

This is one of those perfect examples for why someone would utilize a radial flow scrubber, but this is still a low percentage group and for the majority of divers, they just end up tossing a lot of unused sorb or storing it for long periods of time in the dive locker to maximize the scrubber when a fresh load of litter is sitting right next to the stored scrubber. I find this odd and a bit questionable.


I totally agree with you that there are reasons for the radial scrubber, and that it is a great OEM option, or in the case of the Meg up until recently, an aftermarket add-on. That is why the Meg community has been able to provide Golem with a nice revenue stream for not only the radial, but also the BOV. While my opinion about BOVs is that it should be standard, whether 3rd party or OEM, the radial scrubber is a dive/diver specific add-on. I akin it to 4-wheel drive being standard on most SUV's. Sure, you might utilize it one day, but most of the time it just cost you more gas and maintenance.

BTW, my posts above were more picking fun at the arguments and debate and not really a dig against the HH or Golem. A good friend and dive buddy has the HH and I am impressed like hell over it. I also have a Golem BOV on my Meg, and while my buddy keeps his radial parked most of time, I will probably look at one someday when there is a ligit reason to put 7lbs of litter in the tube.

[mempilot]

Quote: (Originally Posted by RichClark)

I think these two reasons are often understated (particularly) the first when people discuss Radials. I think that most people simply consider a radial as extra scrubber time that's not required for the dive.... Right tool for the job and all that!

With that said, I dive a KISS, so don't have the luxury of choice.

Cheers

Rich

Possibly; however, the CIS Lunar radial has a substantially poorer WOB over not only other radials, but in many opinions, the axial flow as well. This is more than likely a result of the membrane, which is another thing that one must decide, do I really need this?

For some the answer is yes, and they are willing to deal with the negative consequences of utilizing one benefit while creating a deficiency somewhere else.

This is true for the standard axial vs radial debate as well. If the WOB on the axial is exceptional to the point where the WOB is only improved slightly, the the big difference comes down to duration. With WOB set aside at this point, the diver has to look at the dives they do and whether or not they really need the duration. Dive longer than 5 hours in one dive and the answer is yes.

How about the traveling weekend diver as example given above in another post? Doing 9 hours of diving over a weekend on many dives: Easier to pack a radial once than an axial twice? OK. I'll buy that with a grain of salt.

But what happens when there is a minor flood and the scrubber is compromised? The alleviation of toting more sorb to repack just cost the weekend. I'd rather have a 20lb jug sitting there either way, radial or axial, just in case the unit needs repacked for some reason.

So, duration for one dive and I'd say absolutely. Duration for multiple dives and I'd say your pushing your luck for a possible disappointment. WOB, well if that is an issue then absolutely. I don't think it is on the Meg Ax, but that can be subjective. So, for some yes. For all, well I'd guess most will just throw out a bunch of unused sorb. Not a big deal, but why carry it if you don't need it?

[lof]

Quote: (Originally Posted by mempilot)

I'm sorry. I couldn't resist. Which came first, the chicken or the egg? LOL.

Actually it was an Inspiration, guys were diving Twinspirations long before HH or Meg.

[mempilot]

Quote: (Originally Posted by lof)

Actually it was an Inspiration, guys were diving Twinspirations long before HH or Meg.

Well, that was neccessary on even the shallowest and shortest of dives, wasn't it?

[Steve]

Quote: (Originally Posted by mempilot)

I'm sorry. I couldn't resist. Which came first, the chicken or the egg? LOL.

Neither

http://www.rebreatherworld.com/megal...multi-meg.html

[silent running]

Quote: (Originally Posted by mempilot)

I respect that not all axial flow scrubbers are created equal, but the WOB on the Meg Ax is excellent, and from those that I know that go back and forth between the Ax and Rad, it has nothing to do with WOB reasons as they don't perceive the difference or advantage. It is simply a quantity thing. For some of them, it's a bling bling thing as in "I may need it some day."

Well mp, no offence, but I wouldn't call the ISC posted Meg axial 2.50 j/l an excellent WOB figure. Going by ISC's own info, the radial breathes significantly easier. At low RMVs perceived WOB may not be noticeable, but down deep or working hard, or god forbid, working hard down deep, the difference is magnified and would be quite noticeable. IIRC, Cedric Verdier, remarked that he would not have attempted the dive on the Yamishiro with the axial in his Meg. WOB is not a matter of comfort or a bunch of mere dry numbers, it's very, very important.

Anything which can be done to lessen the possibility of retaining CO2 on a CCR should be, IMHO. Unless of course, you're absolutely sure you'll never, ever find yourself working hard or diving beyond recreational limits on CCR.

[mempilot]

Cederic's work is a might cry from what 90% of Rebreather divers out there are doing. We often site these types of dives to justify enhancements to our units, but very few ever do them. For those that do, I wouldn't hesitate to agree that the radial is needed. The BOV is a different story. The BOV serves a huge purpose, even in 10 feet of water.

As for WOB:

CIS rad: 2.57
Meg axial: 2.5
Ext Air: 2.28
Meg rad: 2.22
Prism rad: 2.07

(note: I owned one of the ExtendAir adapters for my Meg. It sucked, big time. I don't trust these numbers, and for CO2 retention, it would have been the worst due to the design. MicroPore confirmed this with me at DEMA.)

The test data shows the Meg Axial and the Meg Radial only .27 apart. EN14143 states that 2.75 is the limit. The Meg Rad is .52 below the limit. The Meg Axial is .25 below the limit. The difference between the axial and rad is only .27, and that is hardly perceptable to the diver.

The radial in question wasn't really the ISC unit anyway. It was comparing the Golem radial to the Meg axial, as the Meg radial has not been available until just recently. If I recall correctly, the Golem radial did not fair any different than the axial scrubber in WOB. In my mind, this eliminated WOB from the decision tree and left duration. Since the duration of the radial goes beyond what most divers (I admit there are dives that require it), even those of us that do technical dives on our RBs, need. I'm not saying don't get one if you want it, but I personally don't see $1k+ enhancement out the unit unless you are pushing 5+ hour dives. If the WOB on the Golem were significantly better than the axial, then I'd be next in line to buy one or the ISC radial at that.

I'll state it again: I really like the HH CCR. I just find it silly to say it is leaps and bounds ahead of the Meg when many of the critical components were designed for the Meg in the first place. Many of the design features that you see in the HH came from the Meg or RBs similar to the Meg. This is not a dig. It is a testament to what works. I think of the Meg as a bare bones Keep It Simple type Rebreather that can be optioned out to whatever configuration the diver wants or needs. I see the HH as a unit that takes the best (in most cases) of those options and makes them standard fare.

I think if you took a Shearwater equipped Meg with an ISC radial scrubber and a Golem BOV, you would have a very serious contender against the HH CCR. The differences would be minor and defendable from both courts.

[Claudio]

I would like to have your opinions about the comparison Megalodon CCR / HH CCR, especially after the publication on the Innerspace website of the comparative tests.
- WOB withof radial ISC / radial Golem
- duration of canisters (radial ISC / radial Golem)
- reliability of thge electronics (APECS 2.5/ HH delrin)
I am very doubtful whether these tests, or some, are truly significant ..

Thanks
Claudio

[diverreb]

Quote: (Originally Posted by mempilot)

Cederic's work is a might cry from what 90% of
I think if you took a Shearwater equipped Meg with an ISC radial scrubber and a Golem BOV, you would have a very serious contender against the HH CCR. The differences would be minor and defendable from both courts.

What about the costs? It seems like the HH comes standard with all the bells & whistles. With the Meg you end up paying quite a bit more.

Also does the Meg come with the option to add a constant flow orifice?

Richie

[mempilot]

Quote: (Originally Posted by diverreb)

What about the costs? It seems like the HH comes standard with all the bells & whistles. With the Meg you end up paying quite a bit more.

Also does the Meg come with the option to add a constant flow orifice?

Richie

Agreed. Merit and price are two different things. To add the BOV to the Meg, you would have to pay retail. I would sincerely doubt that is the case when pricing the HH, as it is packaged in ($500 credit or something like that if you already own one and choose to use it). As for the radial, same thing. I'm guessing a radial equipped Meg from the hatchery would be 'packaged'. The electronics would be the big factor.

I'm sure that ISC will have a major readjustment of pricing when the Apecs3 is complete and can be packaged with the new scrubber. If an OEM BOV was packaged as well without the need to buy one MSRP, then I doubt the price difference between the HH and the Meg would be significant.

At this point, a constant orfice is the only difference then. Well, you have the COPISII for that. Two flavors, and I'm guessing since ISC has done a wonderful job of keeping the two units compatible, that a hybrid is easy to work out.

All in all, this dream Meg doesn't exist today from the factory. So, for someone buying the unit today, they would have to take that into consideration. Either the unit grows with them, or they go for it all up front. Then the real issue comes down to whether or not they want HH electronics, and that is a major question. Me personally, if I was switching over from a HammerMeg or Optima, I would probably be all over the HH right now. If I had a Shearwater Meg, not a chance. Remember too, that many 1st generation Meg owners have already put 5 plus years of depreciation on their units. To do a $3000 electronics conversion is not as big a deal in the pocket book as someone starting from scratch with a new unit. In many cases, they have already added a BOV and/or a radial.