Best tank for dive boats?

[Ulfhedinn]

Since they tend to hot fill and are use to AL80 wouldn't you get the best "possible" gain from a LP say PST95 or 104?

I am use to a 130 so the bigger tank is no issue but just kicking over ideas since I'm land locked today.

 

[Still Kicking]

A 130 is essentially a rerated 104 so both tanks will contain the same amount of air at the same pressure. Don't overthink it.

 

[Manatee Diver]

A 130 is essentially a rerated 104 so both tanks will contain the same amount of air at the same pressure. Don't overthink it.

They aren't exactly the same. A HP130 would have a tank factor of 3.7 while a LP104 would have a tank factor of 3.9. So the 104 would get you a very small amount of air more.

But since we are talking about under fills off of compressors setup to fill AL80s that is only a 6cuft difference at 3,000psi. So I would prefer the HP130 as while you get less gas you won't have a helpful tank filler going "This is only rated to 2,400psi."

OTOH in cave country the choice is the LP10X in doubles, "God's tanks" as the bankmount mafia calls them. But we largely ignore service pressure on modern steel tanks.

 

[Still Kicking]

And buying a duplicate of what is *essentially* the same tank in the hope of getting 6 cf more gas doesn't seem like a great investment to me. But if it's important to you, go for it.

 

[Manatee Diver]

Duplicate... I'm long past duplicate... quadplicate maybe.

 

[Ulfhedinn]

Thanks Guys! Just wanna dive and I an trapped inland... So my mind wanders to what if.

Plus I am cleaning and vis'n the last of my tanks.

 

[Bob DBF]

Depends on the boat compressor and how much time they have to fill. If it's a 3000# compressor and they are doing hot fills you are better off with an LP tank for a good fill. I picked up an LP 95 on a good deal, and use that, although I like other tanks better. Most times they hit about 3k hot regardless of the tank, or they just liked me

If it was a long transit to a new site, or overnight, they would top off before the dive. It still wouldn't fill an HP 100 properly.

 

[lexvil]

LP 85, it looks like an aluminum 80 so it will most often get the 3200 hot fill and you end up with a better fill.

 

[Still Kicking]

LP 85, it looks like an aluminum 80 so it will most often get the 3200 hot fill and you end up with a better fill.

So is a LP85 accidentally filled to 3200 better than a HP100 or 130 legitimately filled to 3200? Don't forget 3200 hot turns to about 2800 pretty quick after you jump in.

At least with HP you can ensure you have more gas for your first, deepest dive.

 

[Manatee Diver]

So is a LP85 accidentally filled to 3200 better than a HP100 or 130 legitimately filled to 3200? Don't forget 3200 hot turns to about 2800 pretty quick after you jump in.

At least with HP you can ensure you have more gas for your first, deepest dive.

Tank factors help comparisons, they are how many cubic feet you get per 100psi, I keep this list in my notes for dive planning, this is just the singles and we just plan LP10X doubles at 8 as there are so at least 4 different LP10X tanks. Also all numbers are rounded down for conservatism.

AL40 1.3
LP50 1.8
AL80 2.5
LP85 3.2
HP100 2.9
LP95 3.5
HP117 3.3
LP104 3.9
HP130 3.7
LP108 4.0
HP133 3.8

HP120 3.4 - There is no similar LP tank.

If you have an easy source for overfills LP tanks would be better. If you don't, HP tanks are the better option IMO.