When to buy tanks?

[inquis]

if they were both to be overfilled the same percentage (for lack of a better term) then the 100 will still hold more than the 85

Nobody considers percentage overfill but instead considers raw fill pressure. This in spite of the fact the hydrostatic testing (every 5 years) is effectively a percentage overfill. The sooner you accept the weirdness the better.

For example, why doesn't an LP85 have 85 cuft at rated pressure? Why in the world is HP rated pressure 3442 psi? (Talk about a weird number, and it's not any nicer in metric units.) Why is an LP tank's (approximate) capacity quoted at the "plus rating" -- 10% higher than standard -- which may go away when you get it hydro tested. (Not all facilities will/can do that test, so if it loses that rating, its service pressure is then 2400... and "rated" capacity of your LP85 is only 74 cuft.) The list goes on. Welcome to the madness!

 

[Wibble]

Also… when looking at tanks, they have an LP and a HP in the steel fabers. Why would I want one vs the other?

That's what I meant about the massively confusing US system of tank choices!

 

[rob.mwpropane]

I didn't see where anyone asked op his size? Height and weight? If you're a 6'2" 250 or 5'6" 175 I would think it would change people's suggestions.

Figure out your SAC, figure out your wife's SAC, and go from there. You might be matched with a 100 and an 80 or maybe 120 and 100. What size is your wife? Steel HP 100's (as someone else mentioned) are usually a good starting point...maybe 120 if you're a bigger guy and an air hog.

A shame you're in FL, I have steel 80, 85, 100, 120, double 85, double 100 you could borrow to see what you like... but I'm 1000 miles away, lol.

 

[rongoodman]

What is a “good deal” on steel 100s these days? And if I’m going to use for nitrox should I just wait til I’m ready to fill with nitrox so I’m not switching back and forth

XS Scuba Faber High Pressure Steel Tank

If you are not using steel cylinders, try to use one and you will soon realize what you have been missing. Faber can offer you the most comprehensive range of cylinders for scuba diving. No other manuf

www.scuba.com

 

[Marie13]

I always go to DGX for tanks.

 

[Fishhy]

What is a “good deal” on steel 100s these days? And if I’m going to use for nitrox should I just wait til I’m ready to fill with nitrox so I’m not switching back and forth

I recently (last 5 months) adopted three orphaned Worthington HP100s (used obviously since Worthington is no longer).
I went with them because of their buoyancy characteristics and the fact they are galvanized (if you're diving in Florida all the time like me you probably don't want painted unless you're always diving springs/caves).
With new hydro, the price I saw was $150 (not a typical deal), $250 (pretty average), $275 (post covid new average). If it's out of hydro, be careful buying used.
Make sure it has some pressure in it or you may have rust inside.
Also, take off the boot and check for pitting/rust
Personally, if I was to look for another galvanized hp100, I'd not want to pay more than about $200 out of hydro.
It may take some time searching facebook marketplace / craigslist, but it's possible. If you don't want to bother with all that, check out divers-supply and get a Faber HP100 hot dipped, they've gone up in the past 6 months as well (was $348+tax, now 400 + tax)

Good luck!

 

[Tracy]

For example, why doesn't an LP85 have 85 cuft at rated pressure? Why in the world is HP rated pressure 3442 psi? (Talk about a weird number, and it's not any nicer in metric units.) Why is an LP tank's (approximate) capacity quoted at the "plus rating" -- 10% higher than standard -- which may go away when you get it hydro tested. (Not all facilities will/can do that test, so if it loses that rating, its service pressure is then 2400... and "rated" capacity of your LP85 is only 74 cuft.) The list goes on. Welcome to the madness!

Is this redundant or are you actually asking?

 

[broncobowsher]

Don't expect HPs to really be overfilled. Most compressors are not going much above what a HP is filled to anyway.

Europe has some 300 bar cylinders and fills, about 4500 PSI. They just don't exist in the states. The cylinders of the compressors to fill them. Hard to get a shop to buy a 300 bar compressor when there are no customers that will use that. Hard to sell a 300 bar tank when you can't get a fill for it anywhere. When the 3000 PSI AL80 came out shops were with compressors that couldn't fill them, it was common for a 3000 PSI fill to cost more than the regular 2250 PSI fill.

There are other issues with 300 bar fills, DIN tank connections that are a little different, 1st stage regulators that cant take the pressure, not backwards compatible with old yoke connections, etc.

 

[Marie13]

@thomasj1107

Just buy the 100s. I read reports here on SB that you can’t be sure of overfills on LPs tanks in FL outside of cave country. I have to drive an hour each way in the Chicago area to get 3000 psi fills on my LP85s. I got the 85s even with the difficulty of getting 3000 fills due to diving SM and 85s hitting the sweet spot as the ideal tanks for that.

 

[Wibble]

Don't expect HPs to really be overfilled. Most compressors are not going much above what a HP is filled to anyway.

Europe has some 300 bar cylinders and fills, about 4500 PSI. They just don't exist in the states. The cylinders of the compressors to fill them. Hard to get a shop to buy a 300 bar compressor when there are no customers that will use that. Hard to sell a 300 bar tank when you can't get a fill for it anywhere. When the 3000 PSI AL80 came out shops were with compressors that couldn't fill them, it was common for a 3000 PSI fill to cost more than the regular 2250 PSI fill.

There are other issues with 300 bar fills, DIN tank connections that are a little different, 1st stage regulators that cant take the pressure, not backwards compatible with old yoke connections, etc.

Also 300 bar fills are harder as they need time to cool before topping off.

In the few months I had a 300 bar 12 litre I don't think I ever managed to get a full fill.