Question What's wrong with a two-bottle cascade?

[GetDownScuba]

Looking at springing for an Oceanus E1 compressor and see it's rated for a max two-bottle system. Just wondering what is the disadvantage in this? I'm an instructor and fill probably 200-300 63/80s in season.
Thanks in advance.

 

[rjack321]

Bauer doesnt want you running an Oceanus all day to refill a 3+ bottle bank. That said the Oceanus can probably handle the quasi-continuous running, Bauer is just pretty conservative about what they will warranty.

 

[GetDownScuba]

Thanks. What I’m wondering is whether it’s worthwhile just to run a cascade with only one high pressure and one low pressure bottle.

 

[PR_SMITH]

Thanks. What I’m wondering is whether it’s worthwhile just to run a cascade with only one high pressure and one low pressure bottle.

It will make your time actually doing fills faster than having no cascades, but overall the time is the same, when you factor in bank refill times.

 

[rx7diver]

Looking at springing for an Oceanus E1 compressor and see it's rated for a max two-bottle system. Just wondering what is the disadvantage in this? I'm an instructor and fill probably 200-300 63/80s in season.
Thanks in advance.

One concern: You can't empty the cascade bottles enough before you have to run the compressor again--either to top up your scuba cylinders or to begin refilling your cascade bottles.

You would be a bit better off, though, if you are using old-school PST 72's (71.2 cu ft @2,475 psig = 2,250 + 10%) rather than Luxfer Al 80's (77.4 cu ft @ 3,000 psig).

rx7diver

 

[rjack321]

Thanks. What I’m wondering is whether it’s worthwhile just to run a cascade with only one high pressure and one low pressure bottle.

How many 80s are you trying to refill pronto, like say you bring home X 80s on Saturday afternoon, how many need refilling before you go out again on Sunday?

Only 2 bank bottles wont help you that much. You could have many more though and just not refill them all in one go. Say you dive on weekends, and use up nearly all of your bank capacity refilling 8x 80s (which would be a bank of probably 6 to 8) on Saturday night then dive again on Sunday. You could refill the bank plus those 8x 80s over the next 4 nights before diving again the next Saturday.

 

[GetDownScuba]

I've got 24 tanks, which is enough to run a 4-student class w/out having to refill. I'd have a few days between classes before having to fill the 80s again. Are you saying I'd need 6-8 bank bottles?

 

[rjack321]

I've got 24 tanks, which is enough to run a 4-student class w/out having to refill. I'd have a few days between classes before having to fill the 80s again. Are you saying I'd need 6-8 bank bottles?

depending on the pressure, yes you'll need ALOT of bank bottles to refill 24x al80s to 3000psi.

 

[GetDownScuba]

I was contemplating a two-bottle system, say 400cf each, so figured between the two, they could fill (from 500 psi) 8-10 tanks. Then, I could refill the banks from the Oceanus and do another 8-10 AL80s in a day or two. Admittedly, pressure physics and math are neither in my wheelhouse or my bilge.

 

[Wookie]

I've got 24 tanks, which is enough to run a 4-student class w/out having to refill. I'd have a few days between classes before having to fill the 80s again. Are you saying I'd need 6-8 bank bottles?

With an 8 bottle 4500 psi cascade arranged in 4 banks of 2 each, you will fill the first 6 80’s at once, but that’s it. You can fill 8 80’s one at a time. Assume the compressor isn’t running. That’s based on practical experience, not calculating volumes and pressures.