Using a HP 120 instead of a HP 80?

[nereas]

Hi to all! I'm very new to scuba and have most of the gear that I need but was wondering about tanks. I did all of my training and check-out dives with an 80cf tank and was thinking about buying my own 120cf tank. What are the pro's & con's on this?
Thanks,
Steve

Most people buy steel tanks because they last a lifetime if cared for properly, whereas aluminum tanks degrade and finally will not pass a hydro eventually.

Modern steel tanks are high pressured, which means a smaller tank can carry more cubic volume of air, nitrox, or trimix. Therefore it makes little sense these days to buy low pressure tanks. There are a few exceptions, but generally HP tanks are preferred to LP.

As for whether to buy an HP 80 or and HP 120, or anything in between, it all depends on what you plan to do with the tanks.

HP 80s work fine for me for single tank diving. Smaller people might be better off with a smaller tank, however, and bigger people with a bigger.

You need to decide what size is best for you, especially if you are a beach diver. Because beach divers pay the price dearly for having a tank too big on their backs every time the walk down or back up the beach when diving.

 

[nereas]

I use a steel HP120 with my single wing because it allows me to trim out really well. I'm five foot nine and it's not too long of a bottle for me.

People often use this exact same rationale for LP 85s.

You should be able to center your tank on your back to trim-out properly with any tank size, and not be fixated on one particular type tank or another.

 

[Colliam7]

I'm very new to scuba ...I did all of my training and check-out dives with an 80cf tank and was thinking about buying my own 120cf tank.

In a separate, long-running thread involving ‘Most regretted gear purchases’, an item high on the ‘regretted’ list was AL80 tanks, in the context of having bought AL instead of steel, and usually in the context of an 80 instead of something / anything bigger. Putting aside the AL issue, part of the reasoning simply involved gas supply – if you are a newer diver you may be a bit more of an ‘air hog’ and get a little frustrated by having to turn dives a bit earlier than more experienced divers with lower SAC rates; or, if you are diving deeper, and using therefore use air more rapidly, a bigger tank gives you a chance to enjoy the dive a little longer, while remaining well within your NDL (I have not had the experience on east coast boat charters of being told to limit my dive time, other than to to stay within NDL and to re-board with no less than 500 psi). Personally, I prefer HP steel tanks for singles diving and like the 120. Yes, the 120 is a bit heavy (and the shore diving comment merits specific attention), and a bit long. But, since I usually like to dive a bit deeper on rec dives (100 –130 ft) off the NC coast, I like having more gas. Why carry only 80 if I can carry 120? As jbres1 said, more bottom time and less lead on your belt (or in your BC). In fact, I will buy HP130s next for single tanks, having doubled up my 120s. I have not had the problem of a heavy tank rolling me over.

Having a tank that holds more gas than you have allowable bottom time is no advantage. This will cost you money filling partially full tanks.

At least in the shops I use in NC, a 3442 psi with 1500 psi remaining will cost no more to fill than a 3442 psi with 500 psi remaining. Yes, the cost / fill for a 120 can be slightly higher in some shops than for an 80, but it is a trivial difference. In fact, you just may be able to squeeze an extra (short, shallow) dive out of a larger tank between fills.

 

[beester]

Where I live (Belgium)... double valved steel HP 120 cf (actually here they are 119 cf) tanks are the norm for males.

Most dives done here are shore dives. In my opinion a normal guy should not have any issues with carrying a steel 120cf tank for any length of time (we sometimes have to walk fully equipped on a dike for up to half a mile, crossing barbed wire and then climb down the dike over oyster embedded slippery rock).

Big pro's for a steel 120 cf tank are:

-reduce the lead weight you carry (the volume vs weight of a steel tank is negative (filled) to neutral)
-quality of steel vs aluminium... we have guys in my club who still dive tanks from the 70's (those were low pressure steel tanks btw).
-big amount of gas...more then enough for a normal person to do 100 or 120 feet wreck dives. The average person diving to 60 feet for an hour will come up with almost 50% of gas in tank left. So big margin for errors or if you want... gas for a shallow 2nd dive.

Filling for us is not an issue.. we can fill for free at the club... next most filling stations will only charge what you fill... not depending on tank volume.

Negative
-because of the bigger volume of the tank it could be less stable on your back while diving (also depending on bcd). Some people like double 80cfs more because of the better stability.

 

[Randy43068]

People often use this exact same rationale for LP 85s.

You should be able to center your tank on your back to trim-out properly with any tank size, and not be fixated on one particular type tank or another.

Maybe... the 120 fits my DIR hose lengths the best and allows me almost perfect trim. I could give two ****s what tank someone else uses, I was just saying why I like the 120 for my body type and configuration. Using the steel 120 allows me to use less led on my belt, too.

 

[MNJoe]

I had the opportunity to dive a HP 120 stl tank a few months ago. I was somewhat nervous about all the cons against a large tank. I am 5' 10", 185lbs, I did not notice any cons against the larger tank, although I will say I was boat diving, so I did not have to carry it. The extra air was great!!!

MNJoe

 

[Randy43068]

Where I live (Belgium)... double valved steel HP 120 cf (actually here they are 119 cf) tanks are the norm for males.

Most dives done here are shore dives. In my opinion a normal guy should not have any issues with carrying a steel 120cf tank for any length of time (we sometimes have to walk fully equipped on a dike for up to half a mile, crossing barbed wire and then climb down the dike over oyster embedded slippery rock).

Big pro's for a steel 120 cf tank are:

-reduce the lead weight you carry (the volume vs weight of a steel tank is negative (filled) to neutral)
-quality of steel vs aluminium... we have guys in my club who still dive tanks from the 70's (those were low pressure steel tanks btw).
-big amount of gas...more then enough for a normal person to do 100 or 120 feet wreck dives. The average person diving to 60 feet for an hour will come up with almost 50% of gas in tank left. So big margin for errors or if you want... gas for a shallow 2nd dive.

Filling for us is not an issue.. we can fill for free at the club... next most filling stations will only charge what you fill... not depending on tank volume.

Negative
-because of the bigger volume of the tank it could be less stable on your back while diving (also depending on bcd). Some people like double 80cfs more because of the better stability.

Try not to confuses the masses. The 120 is a different animal than the 119. If it's PST you're talking about. The 119 is 8 inches, where the 120 is the seven and a quarter one. (diameter)

 

[SteveTW]

Thank you all for your input. And I did read all the posts. Like I said, I'm new to diving and I've been told that my breathing will get better with time (more dives) but I think I'll be looking into a HP120 for my first tank.

I hope you guys don't argue over this. We're all different and are use to different gear.
Thanks, Steve

 

[diver_pirate]

I use the X7-119 Its almost identical height and diameter to the AL80. Warm water to 60 ft the 80 is fine. Cool water and wrecks the 119 reduces weight on your hips. the 119 is 4 pounds lighter than the 120 but costs $50 more. I thought it was worth it.

Also, if you only have one what do you do for the second dive?
DP

 

[rawls]

Let me give you some wisdom...
If you buy the 120's with H-valves that also have yolk adapters, they will come...All of the friends you didn't even know you had will want to use them....
Two of my "friends"...one, a fellow instructor, the other a DM are going to the Cooper River this weekend. My buddy the DM approached me first and asked if he could use them...then my buddy instructor heard him and said....I was going to use them. They are going to use one apiece...In the end...after my first buddy asked if he could use them and the bickering began, neither of them asked me again and the DM buddy didn't even wait for my reply....True story...

I actually love my Worthington 120's. I am 6'4 and can trim out great with them...that is when I get to use them...