Neutral AL80's Question

[JKSteger]

I'm looking to purchase a couple of tanks and have been looking at the Luxfer S80N tanks. They are supposed to be neutrally bouyant when empty...actually +.05 pounds.

They cost about $25.00 more than the standard AL80. I'm wondering which I should get the regular AL80 or the S80N (Neutral). The only tank I've ever used is rental AL80's. So this will be my first tank purchase.

If I did get the S80N what has been your experience on getting a full fill? I noticed that a full fill is actually 3300psi compared to the 3000psi that a regular AL80 has. When I searched thru the past posts I noticed that alot of times you had to point out the 3300psi on the tank to the shop doing the fill but I wanted to know if even after you point that out do they actually fill to 3300 or just take it to 3000psi anyway?

Also a stupid question here...when getting your tank refilled, how long does that actually take. I'm asking because all I've used have been the dive shop rentals and if I need a fill and take it back to the dive shop (think shore dives) for more air they just "swap" it out with another tank that is ready to go and has air already in it. What should I expect when needing to get my tank filled at say a station that is located at a popular shore dive site. (think Jetties, Lake or quary).

Thanks,
Jeremy

 

[Hoosier]

1. Depending on the station, they mostly fill between 3200 psi and 3300 psi.
2. Depending on the capacity of compressor they have, the air station usually fills up your tank within 7 min.

I'm looking to purchase a couple of tanks and have been looking at the Luxfer S80N tanks. They are supposed to be neutrally bouyant when empty...actually +.05 pounds.

They cost about $25.00 more than the standard AL80. I'm wondering which I should get the regular AL80 or the S80N (Neutral). The only tank I've ever used is rental AL80's. So this will be my first tank purchase.

If I did get the S80N what has been your experience on getting a full fill? I noticed that a full fill is actually 3300psi compared to the 3000psi that a regular AL80 has. When I searched thru the past posts I noticed that alot of times you had to point out the 3300psi on the tank to the shop doing the fill but I wanted to know if even after you point that out do they actually fill to 3300 or just take it to 3000psi anyway?

Also a stupid question here...when getting your tank refilled, how long does that actually take. I'm asking because all I've used have been the dive shop rentals and if I need a fill and take it back to the dive shop (think shore dives) for more air they just "swap" it out with another tank that is ready to go and has air already in it. What should I expect when needing to get my tank filled at say a station that is located at a popular shore dive site. (think Jetties, Lake or quary).

Thanks,
Jeremy

 

[Doc Intrepid]

1. Depending on the station, they mostly fill between 3200 psi and 3300 psi.
2. Depending on the capacity of compressor they have, the air station usually fills up your tank within 7 min.

1. Depending on the station, the number of whips they have off the banks, the number of bottles currently full in their banks, how hot their compressor is, how hot the ambient temperature is that day, and how busy their tank monkey is at pushing tanks out the door, they mostly fill between 3200 psi and 3300 psi as 'hot fills' which then cool down to around 3000 if all the other things are in your favor and you were not evil in a former lifetime.

2. Depending on how busy it is, how many divers/instructors/classes are currently in the shop, how long the line is, whether anyone remembered to bring the tank monkey lunch that day, whether s/he has any help in physically moving tanks around inside the fill station, and what other chaos is going on in the shop at the same time, your tank will be filled in 7 minutes AFTER the whip has been attached to your valve, which might be an hour or two after you dropped your tank off to be filled at the fill station.

There are pros and cons to owning your own tanks. One of the disadvantages is that you can't simply drop off a shop empty and immediately grab a full shop rental tank!

The Luxfer 80 neutrals are nice tanks. I just bought two of them. I like them. But I can fill them myself, very slowly, to 3400 psi or so, so that I get a good fill each time. (There will nearly always be some cooling down of the contents, with a resulting drop in psi gauge.)

In order for shops to fill your Luxfer neutral 80 tanks to 3300, particularly given that your tanks are seldom likely to be the ONLY tanks in line to be filled, they will need to fill to slightly higher than 3300. This means that the governor on the system needs to be set as high as 3500 psi. Depending on whether they fill many steel tanks or not, it may or may not be. If they have to turn it up, and they're real busy, they might not always give you the extra gas. If this doesn't matter to you, have at it. You certainly ought to bring to the person's attention that you want him/her to fill it so its at 3300 psi after it cools.

But my suggestion is that you sit down and write out your answer to the question: "why do I think I need neutral aluminum 80s?" If you have some excellent rationale, then the potential problems involved in getting a good fill likely won't matter to you. But if there isn't any real good reason for you to need that specific tank, then you might be happier in the long run with the standard Luxfer aluminum 80s. (And, by the way, if you haven't taken a look at steel tanks, you may want to do so prior to buying any tanks. Steels offer better bouyancy characteristics than the neutrals, together with more flexible fill options as well. Just a thought.)

Best of luck with your tank purchase.

Doc

 

[JKSteger]

Thanks for the advise and answers. I was looking at the steel tanks but they are rather pricey...but the few extra $$$ should be well spent over the course of 20 or 30 years of tank use.
I saw on another thread that a couple where trying to decide on the neutral 80's or regular 80's and decided that since everywhere they go dive, the local dive shop pushes out AL80's by the masses and since they were used to diving with AL80's already and had adjusted for the bouyancy characteristics of AL80 and that they might not get the full 3300psi fill on the neutral tanks they decided to stick with the AL80's and look into getting some steel tanks a little later on.
I think I will ponder on this a while longer before making a purchase...it's not like the rental tanks are going away anytime soon...so I can take my time.

Thanks to all,
Jeremy

 

[matt_unique]

I'm looking to purchase a couple of tanks and have been looking at the Luxfer S80N tanks. They are supposed to be neutrally bouyant when empty...actually +.05 pounds.

They cost about $25.00 more than the standard AL80. I'm wondering which I should get the regular AL80 or the S80N (Neutral). The only tank I've ever used is rental AL80's. So this will be my first tank purchase.

If I did get the S80N what has been your experience on getting a full fill? I noticed that a full fill is actually 3300psi compared to the 3000psi that a regular AL80 has. When I searched thru the past posts I noticed that alot of times you had to point out the 3300psi on the tank to the shop doing the fill but I wanted to know if even after you point that out do they actually fill to 3300 or just take it to 3000psi anyway?

Also a stupid question here...when getting your tank refilled, how long does that actually take. I'm asking because all I've used have been the dive shop rentals and if I need a fill and take it back to the dive shop (think shore dives) for more air they just "swap" it out with another tank that is ready to go and has air already in it. What should I expect when needing to get my tank filled at say a station that is located at a popular shore dive site. (think Jetties, Lake or quary).

Thanks,
Jeremy

Alum 80's are allowed a 10% overfill (thus the 3300psi) as you know. The slower (cooler) the fill the less it will cool and decrease in pressure by the time you use it. You can leave the shop with 3300 and the following day open your valve and find 2900 psi for example. The best is a nice slow fill, 10 minutes for example. Then 10 minutes to let it cool, then a slow top off. I always hang around and watch the fill whenever possible. I sometimes ask them for a slower fill. In fact I make sure I blast a little air out of the valve before they connect the whip and lower it into the water tank (if the shop has one). Sometimes the shop will let me do my own fill depending upon who is working.

A neutral 80 would certainly allow you to carry a little less weight. A regular alum 80 has a 6 pound swing from full to empty.

Steels are great but very pricey in comparison to alum's. If I had extra money I would get some but the (double) alum 80's I use are just fine.

--Matt

 

[The Kraken]

Jer,
Next time we gather up at the mud puddle I'll let you try my E7-80 and E8-119 to see what ya think.

The K

 

[oxyhacker]

The extra 300 psi isn't an overfill - the neutral 80s are a whole different animal, built and rated for the higher pressure.

Also, the swing from full to empty is totally a function of the weight of the air in a tank, so your statement that "a regular alum 80 has a 6 lb swing" while true is a little misleading because it suggest that other 80's might not. Any 80, be it 3000 psi, 3300 psi, alu, steel or composite, will have the same swing.

If one looks at the specs for the neutral 80s, one will notice that they are 4 pounds heavier than a standard alu, just about the same amount as they are less buoyant by. So while you may use a little less lead, you'll still be lugging the same total weight around. Strap a 4lb weight to a standard 80 and it becomes functionally identical to a N80.

The other thing is, with any tank which has an oddball pressure like the N80, one is much more likely to get short fills. Most shops will just look at it and say "Oh, an aluminum tank, that's 3000 psi".

Seeing as how the regular 80s are the standard and that most of the tanks you will ever rent are regular 80s, and that the N80s are more expensive and more likely to get a short fill, it makes more sense to me to get used to the standard 80s unless you got some really good reason for needing a slightly shorter tank.

Alum 80's are allowed a 10% overfill (thus the 3300psi) as you know. SNIP
A neutral 80 would certainly allow you to carry a little less weight. A regular alum 80 has a 6 pound swing from full to empty.

--Matt

 

[JKSteger]

Jer,

Next time we gather up at the mud puddle I'll let you try my E7-80 and E8-119 to see what ya think.

The K

Thanks for the offer and I will take you up on that one. Also want to try out a BP/W setup too. ...So if you have a setup I can "demo" at the ole mud puddle that would be great.
<BTW, first order of business is getting a semi-dry suit for Lanier, Jocassee, etc. It's just too cold in the 5mm.>

Jeremy

 

[Hoosier]

After trying out whatever you want, if you think that you will eventually go to BP/W and double tank setup, just go ahead from the begining stage. Otherwise, you have to pay extra cost for your gear upgrade. Many divers took the same path as paying additional cost later on. Yes, I am one of them.

 

[scubaPT]

Jeremy,
I'm not sure how much a neutral 80 costs, but you can get a new Faber LP95 for 190.00 off ebay, with shipping to Griffin you are looking at about 215.00. You will get more air than an 80 which gives you more bottom time.
I took about 8 pounds off my belt with the 95

Allen