Bigger tanks and dive ops

[diveborg]

Can someone explain the differences between using high pressure or low pressure tanks? Are there advantages or disadvantages to either? Does using one or the other impact other areas of the dive?

Thanks

HP tanks have a higher PSI when they are full. An 80 cf. HP tank is full at 3500 PSI if they are Pressed Steel brand. At this high of pressure, you will almost always find a DIN valve on the tank. The benefit is that the tank has a smaller overall size than a LP tank.

LP tanks reach their rated capacity at a lower pressure. An 80 cf is full at 2400 psi. These tanks will have a yoke valve. They have to be a bit larger in size in order to hold the same cubic feet of air as a HP tank.

The benefit of a steel tank is that is stays negatively buoyant even when near empty, unlike the usual aluminum tank that becomes 2-4 lbs positively buoyant at the end of the dive.

I personally have LP 80 tanks at home and really like them.

 

[Jim Baldwin]

Junko,

There at three dive operators that I have used in Cozumel that use steel tanks in their normal course of business.

Aldora

They use High Pressure Pressed Steel Tanks. These tanks require the use of DIN adapter and must be filled to 3500 psi in order to get a full fill. Any pressure less than that and you are not getting what you paid for. If a 120 cu. ft. is filled to 3000 instead
of 3500 you get 103 cu. ft. instead of 120.
I found this was the case when I dove with Aldora on two seperate dive trips.
These tanks are 7.25 inches in diameter and are heavier than aluminum and negative at the end of the dive.

Liquid Blue

Uses the new E series tanks from Pressued Steel. They are rated at 3445 psi and come with the screw out disc that allows the use of DIN or yoke regulators.
These tanks also have to be filled to 3445 in order to get the actual rated volume. In June I dove with Liquid Blue for three days and found that the tanks were filled to 3000 to 3100. These tanks are also 7.25 in diameter and are also negative at the end of the dive.

Living Underwater

Uses Pressed Steel low pressure 95 and 120 cu. ft. tanks that come standard with a yoke valve. They are full at 2400 psi. Anything over that and you are getting more cu. ft. Dove with them Nov. 19-25. Made 12 dives in 6 days. Each tank I used had between 2700 to 3000 psi.

These tanks are 8 inches in diameter and weigh about 50 lbs when full. They take a little getting used to. I don't use any weight when I dive with the 95 or 120.

I have used Living Underwater on my last five trips but am not opposed to diving with Liquid Blue or Aldora.

These are the only three operators that I know of that use steel tanks and advertise the big tanks along with computer diving.

Many of the other operators will offer 100 alum. or 95 lp tanks at about $10 extra per tank on a two tank dive. By the time I do this which when I started diving in Cozumel I did. Then I'm paying more than if I'm diving with one of these other operators who specialize in longer, deeper profiles with less people.

I dive with Pressed Steel High Pressure 100 and 120's and have several Al 80's rigged as stage and deco bottles all rigged with DIN fittings. I just use a DIN adapter when I use tanks equipped with a yoke valve.

Hope this helps to answer your question about the tank size/volume and the dive ops.

Jim
Louisiana

 

[Christi]

Junko,

There at three dive operators that I have used in Cozumel that use steel tanks in their normal course of business.

Aldora

They use High Pressure Pressed Steel Tanks. These tanks require the use of DIN adapter and must be filled to 3500 psi in order to get a full fill. Any pressure less than that and you are not getting what you paid for. If a 120 cu. ft. is filled to 3000 instead
of 3500 you get 103 cu. ft. instead of 120.
I found this was the case when I dove with Aldora on two seperate dive trips.
These tanks are 7.25 inches in diameter and are heavier than aluminum and negative at the end of the dive.

Liquid Blue

Uses the new E series tanks from Pressued Steel. They are rated at 3445 psi and come with the screw out disc that allows the use of DIN or yoke regulators.
These tanks also have to be filled to 3445 in order to get the actual rated volume. In June I dove with Liquid Blue for three days and found that the tanks were filled to 3000 to 3100. These tanks are also 7.25 in diameter and are also negative at the end of the dive.

Living Underwater

Uses Pressed Steel low pressure 95 and 120 cu. ft. tanks that come standard with a yoke valve. They are full at 2400 psi. Anything over that and you are getting more cu. ft. Dove with them Nov. 19-25. Made 12 dives in 6 days. Each tank I used had between 2700 to 3000 psi.

These tanks are 8 inches in diameter and weigh about 50 lbs when full. They take a little getting used to. I don't use any weight when I dive with the 95 or 120.

I have used Living Underwater on my last five trips but am not opposed to diving with Liquid Blue or Aldora.

These are the only three operators that I know of that use steel tanks and advertise the big tanks along with computer diving.

Many of the other operators will offer 100 alum. or 95 lp tanks at about $10 extra per tank on a two tank dive. By the time I do this which when I started diving in Cozumel I did. Then I'm paying more than if I'm diving with one of these other operators who specialize in longer, deeper profiles with less people.

I dive with Pressed Steel High Pressure 100 and 120's and have several Al 80's rigged as stage and deco bottles all rigged with DIN fittings. I just use a DIN adapter when I use tanks equipped with a yoke valve.

Hope this helps to answer your question about the tank size/volume and the dive ops.

Jim
Louisiana

Jim,

For what it's worth, none of the three above operators fill their own tanks, so short fills are not to cheat the customers or to save money. Providing short fills serves no purpose to the operators. We all get our fills from the same place.

Second, I don't know ANY operators that charge $10 extra per tank for an AL 100. $3 per tank is the max additional charge I have seen. Nitrox fills are a standard $10 per fill, but not the AL 100's. I give them to divers with less efficient air management at no additional charge when available. Otherwise, we still average an hour or more on AL 80's...don't need the big heavy tanks to get a longer than average bottom time. Computers are also provided to those who don't have them.

 

[diveborg]

Liquid Blue

Uses the new E series tanks from Pressued Steel. They are rated at 3445 psi and come with the screw out disc that allows the use of DIN or yoke regulators.
These tanks also have to be filled to 3445 in order to get the actual rated volume. In June I dove with Liquid Blue for three days and found that the tanks were filled to 3000 to 3100. These tanks are also 7.25 in diameter and are also negative at the end of the dive.

While I haven't gone out with Liquid Blue yet, I did read on their web site, and I quote: "Liquid Blue Divers features PST low-pressure steel tanks (100 c.f. and 120 c.f.), ". In my experience, Pressed Steel LP tanks are rated at 2400psi with a 10% over-fill rating. At least mine are. Is their web information incorrect, or have they gotten different tanks? I'll be diving with them in 8 days, so I'll find out for myself.

In any case, I prefer the steel tank over the AL tank and having a large tank is just an added bonus.