what kind of tank?
- Thread starter platvis
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scubasean
Contributor
I'm not sure what 3000lBAR means....Aren't they either measured in liters or cu. ft. (at a given pressure[BAR or PSI])?
But maybe I'll learn something.
But maybe I'll learn something.
Wrapped tanks are now available for Scuba and are lighter but are also very expensive at about $400 each. I am also not sure how widely available they are yet.
One thing to consider however is that a lighter tank often does not really save any weight. You need to be neutrally bouyant in the water and a light tank will require more lead on your weight belt. So in effect, your ready-to-go-diving weight will be basically the same with a lighter and more bouyant tank.
The only way to get around this is by designing the tank to use a very high service pressure in the 4000-5000 psi range to minimize the tank's displacement while allowing adequate air volume. This has it's downside though as it can cause problems in getting them filled. Many LDS's charge more for filling to this extreme pressure and many cannot give you a complete fill at all.
Another thing to consider is that with any wrapped tank, if you put a nick or gouge in the side, you can plan on throwing it away as the nick leads to water infiltration and delamination of the overwrap. I am not sure on these tanks, but many wrapped/composite tanks also have a limited lifespan of 10 to 15 yrs.
If you really need something close to 105 cu ft or 3000 liters I would go with a steel tank. They are comparatively heavy but also have good bouyancy characteristics and you will be able to pull some of the lead off your weight belt. They are also half the price and extremely durable.
If you really need to save weight, using a smaller tank may be a more viable option unless you really need the extra air.
One thing to consider however is that a lighter tank often does not really save any weight. You need to be neutrally bouyant in the water and a light tank will require more lead on your weight belt. So in effect, your ready-to-go-diving weight will be basically the same with a lighter and more bouyant tank.
The only way to get around this is by designing the tank to use a very high service pressure in the 4000-5000 psi range to minimize the tank's displacement while allowing adequate air volume. This has it's downside though as it can cause problems in getting them filled. Many LDS's charge more for filling to this extreme pressure and many cannot give you a complete fill at all.
Another thing to consider is that with any wrapped tank, if you put a nick or gouge in the side, you can plan on throwing it away as the nick leads to water infiltration and delamination of the overwrap. I am not sure on these tanks, but many wrapped/composite tanks also have a limited lifespan of 10 to 15 yrs.
If you really need something close to 105 cu ft or 3000 liters I would go with a steel tank. They are comparatively heavy but also have good bouyancy characteristics and you will be able to pull some of the lead off your weight belt. They are also half the price and extremely durable.
If you really need to save weight, using a smaller tank may be a more viable option unless you really need the extra air.
DIR Tec Diver
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If you dive with a wetsuit then aluminum tanks.
If you dive with a dry suit then steel tanks.
You get the tank size depending on your dive and your calculations of your SAC rate and rock bottom. Then you know exactly the air pressure needed to dive the depth and time required as well as ensuring you have enough gas to donate to an out of air diver.
If you dive with a dry suit then steel tanks.
You get the tank size depending on your dive and your calculations of your SAC rate and rock bottom. Then you know exactly the air pressure needed to dive the depth and time required as well as ensuring you have enough gas to donate to an out of air diver.
That's a "blanket statement" that can be easily taken "too literally". Two things are important: Be neutral at 15' with minimal (300psi) gas in your tanks and be able to swim up your rig w/ no air in your BC/wing from depth with everything full (dropping weight if required).
Arnaud
Contributor
Platvis, beyond the debate steel vs. aluminum, there are certain differences between the States (where most board members are located) and Europe when it comes to tanks. The size (not talking about the measurement unit) and the brands are different and the max. pressure usually is too.
If you dive mostly in cold water with a thick exposure suit (dry or wet), no doubt you'd want a steel tank. But that's usually what's available in Europe. As for the choice of the actual tank, you're probably better off asking the LDS' that are available in your area. Tanks are not really convenient to mail order...
Also, the size of a tank should be based on your gas needs, your buddy's needs, and your own size. Bigger is not necessarily better depending on the type of diving you'r doing.
Finally, my understanding of European measurements is that tanks are described by the amount of water they (theoretically) contain. A 15l tank will contain 15l of air at the surface (1 bar). At 200 bars, the same tank will contain 3000 liters of air.
If you dive mostly in cold water with a thick exposure suit (dry or wet), no doubt you'd want a steel tank. But that's usually what's available in Europe. As for the choice of the actual tank, you're probably better off asking the LDS' that are available in your area. Tanks are not really convenient to mail order...
Also, the size of a tank should be based on your gas needs, your buddy's needs, and your own size. Bigger is not necessarily better depending on the type of diving you'r doing.
Finally, my understanding of European measurements is that tanks are described by the amount of water they (theoretically) contain. A 15l tank will contain 15l of air at the surface (1 bar). At 200 bars, the same tank will contain 3000 liters of air.
thanks for the advice guys
further info
We dive mostly in the Eastern Schelde Delta (a marine reserve in the south of the Netherlands) in water with a temperature between 4 and 21°C with a neoprene suit with a thickness between 7 and 12 mm. The total weight of all the dive gear on the body is around 35 kg.
So you'll understand that a 25 kg tank on the back is backkilling especially for my girlfriend.
Karel
further info
We dive mostly in the Eastern Schelde Delta (a marine reserve in the south of the Netherlands) in water with a temperature between 4 and 21°C with a neoprene suit with a thickness between 7 and 12 mm. The total weight of all the dive gear on the body is around 35 kg.
So you'll understand that a 25 kg tank on the back is backkilling especially for my girlfriend.
Karel
Arnaud
Contributor
The weight doesn't matter. What matters is the buoyancy characteristics of the tank. More negative buoyancy means you'll need less lead on your waist... If you have a tank that's very buoyant (Aluminum), and you wear 7 to 12 mil. of neoprene, you'll need to carry a whole lot more lead than with a good steel.
Also, your girlfriend's SAC is likely to be less than yours. So she will likely need a smaller tank than you for the same bottom time.
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