Making the leap: help choosing first rb

[NAND]

I brought it up because Delrin, aka “plastic bottle” , seems like a better material choice for a scrubber housing than say aluminum. The heat transfer rates are several orders of magnitude different.

Actually, you can not build a scrubber using aluminium. The reason is, that small amounts of NaOH within the sorbent will in presence of water protonize same to NaAlO2 and H2- with other words- it wont be there for long... Neither would be you under certain circumstances mixing H2 and O2

In my opinion POM (more precisely POM-C) is a fairly good choice- given the requirement of form stability and high PH it offers a good cost-benefit ratio.

Why are you concerned about the thermal conductivity per se?

If this was a major concern in material choice GFRPs offer much better thermal insulation capabilities at higher strenghts and durability. This has however noch much advantage as the scrubber itself is usually sufficiently insulated by an air layer.

 

[Dusty123]

"Yeah, really like comparing apples and hammers. I bashed that POS for years before all the innovations.

WOB sucked, electronics sucked, nonpackable scrubber sucked, etc, etc, etc. The FX was total crap.

And as much as I hate the revo, I’d rather dive it than the FX with Hammerhead Electronics"



Well its the same kind of thing if you compare a steel mini to a titanium micro, all these things evolve.

That advantage of delrin despite being pricey (just pass on to end user) you can machine it at ludicrous speed.

 

[Superlyte27]

I had 4 REVO’s before I bought my first optima. I’m very familiar with all of the options

I was one of the few people that didn’t have broken RMS

 

[broncobowsher]

And the RMS has evolved as well. It is now bordering on being "robust".
I don't think I have heard of any spontaneous failures in the latest design. But that has only been a couple of years.

 

[LandonL]

lol, Do you have any clue how many Optimas are sold nationwide and worldwide?

Has anyone ever shown reliable numbers for this? Would be interesting to know.

If we are going on strictly the number of units sold, I think the AP probably holds the crown there. I have been diving an AP Evolution for about 8 years now. I did at one point buy an Optima to try out, but unfortunately wasn't a huge fan.

 

[lostsheep]

Why are you concerned about the thermal conductivity per se?

Scrubbers do better in warmer environments. It seems as though you would not want material with a high thermal conductivity for the housing of a scrubber. I was defending the choice of delrin / acetal in this application because of the "plastic bottle" comment. Plastic carries an inferior connotation with many people and I disagree with that paradigm. There is no perfect material choice for anything and every design decision involves trade-offs.

Aluminum ~ 167 W/m-K
Acetal ~ 0.390 W/m-K

Both numbers pulled from MATWEB

 

[Superlyte27]

Has anyone ever shown reliable numbers for this? Would be interesting to know.

If we are going on strictly the number of units sold, I think the AP probably holds the crown there. I have been diving an AP Evolution for about 8 years now. I did at one point buy an Optima to try out, but unfortunately wasn't a huge fan.

I know the number. Not sure it’s supposed to be public knowledge.

 

[rsingler]

Scrubbers do better in warmer environments. It seems as though you would not want material with a high thermal conductivity for the housing of a scrubber. I was defending the choice of delrin / acetal in this application because of the "plastic bottle" comment. Plastic carries an inferior connotation with many people and I disagree with that paradigm. There is no perfect material choice for anything and every design decision involves trade-offs.

Aluminum ~ 167 W/m-K
Acetal ~ 0.390 W/m-K

Both numbers pulled from MATWEB

If that was all there was to it, how do the JJ divers with Aluminum cans do all those cold water dives? I think air provides great insulation, and how it is routed to the scrubber is probably equally as important as the thermal conductivity of the can.

 

[tbone1004]

If that was all there was to it, how do the JJ divers with Aluminum cans do all those cold water dives? I think air provides great insulation, and how it is routed to the scrubber is probably equally as important as the thermal conductivity of the can.

and the SF2 which is carbon fiber which is highly conductive.

@lostsheep remember that in most designs the canister is not in direct contact with the scrubber. There is usually an air barrier between them and too hot is not necessarily good either. In "normal" water temps, most loops get quite hot. My Meg has an aluminum canister and if the water is over about 75 I have to dil flush every 20 or so minutes to cool the loop off because it gets uncomfortable to breathe.

 

[lostsheep]

If that was all there was to it, how do the JJ divers with Aluminum cans do all those cold water dives? I think air provides great insulation, and how it is routed to the scrubber is probably equally as important as the thermal conductivity of the can.

In no way shape or form is that "all there is to it" , I never intended to claim or otherwise insinuate that it was.