However, they have a pair of tanks for sale. I've bought a couple of used AL80s before, but not steel. They're both 3AA, so chrome-molybdenum steel. One dated 2/72, the other 1/75. I know one is a Dacor. Other than that, I have no idea of the history on them, other than the last visual appears to have been done in 88. Exterior wise, they look to be in good shape.
Is there anything else I should be looking for? Pop the valves and look inside? I can get the whole kit for $75; wish he'd part with just the tanks.
ETA: Looks like the working pressure on both is 2250; perhaps one of you can decipher just what that would mean. I'm still a little new at buying/inspecting tanks. Look to be the same size as my AL 80s, what would that make them?
Those are probably LP72s, which were widely used from 1965 until aluminum cylinders became popular in the late 1970s. The diameter should be slightly smaller than an AL80, 6.9" rather than 7.25". If they have a vinyl coating, the thickness of the coating is enough to make the diameter measure out closer to 7".
I have 11 of them and find them useful for a wide variety of things. They're like an AL80 only neutrally buoyant.
Dacor didn't manufacture cylinders, they resold them, as did US Divers and others. The three manufacturers were PST, Norris, and Walter Kidde. PST Cylinders are marked "PST" somewhere (Or the PST logo), Norris have the N-in-a-diamond device and a serial number starting with H, and Kidde have a serial number starting with K.
Here are the things to watch:
1) Serious internal corrosion makes them unusable. You can look inside, but there will nearly always be some flash rust and often some mild pitting, and it takes an experienced eye (and ideally, the right tools) to determine whether it's bad enough to matter.
2) Be sure they have a standard valve thread. There are some tapered thread LP72s and some with an M18 thread. In general those cylinders aren't worth the extra hassle.
3) Either replace the entire valve or the burst disc after they pass hydro, especially if they have a flush-mount axial-outlet burst disc, as these are not safe -- see my recent A&I thread on this. After overhauling a lot of valves I've reached the point where I just replace them.
4) Make sure you can get them filled. I don't have any trouble with fills here, but some people in Florida report that none of their local dive shops will fill them.
5) Make sure your hydro shop will + rate them unless you have a place that will fill them to 2475 PSI without the + rating (or unless you're willing to settle for short fills). One local hydro shop here will + rate PST cylinders only, one will + rate PST and Norris but not Kidde, and there are some hydro shops out of my area that will + rate Kidde.
6) Some of these have an interior epoxy liner. If present typically they have to be removed by tumbling or shot blasting although if they are in great shape and you don't plan to use Nitrox you can leave them. Be sure you have a shop that will shot blast or tumble out the liner at a reasonable rate. I get mine shot blasted for $20 or so, but I'm told the liners can be tumbled out pretty quickly using a few pounds of sheet metal screws as the media.
7) Some were galvanized, some painted, some have a vinyl coating either over the galvanizing or over the plain steel. Any will work although I prefer the galvanized ones for ease of maintenance. The vinyl coating can be removed in various ways if necessary. I use a heat gun and a knife. Painted cylinders can be sandblasted and repainted but this adds to the cost.
I typically pay $40 for a used LP72 and figure I'll have $100 in it on average by the time I allow for a few that don't fail hydro, and add the cost of hydro, shot blast, and a valve. I usually only go through all this with cylinders that are galvanized, that I can get + rated, and that have a standard neck thread. I figure it's worth it, and I prefer them to aluminum cylinders.
