Aluminum 80CF Scuba Diving Tank with Combo Valve

This is a Cyl-Tec aluminum 80 cubic foot scuba cylinder with a combo valve, rated to 3000 psi (207 bar) and certified DOT/TC. It is the standard size of recreational diving, sold as new stock and shipped empty.

Who this suits

Divers who are tired of renting. Cyl-Tec lists it for beginner and experienced divers alike, and that is fair: an aluminum 80 is what you learned on, what the boat hands you, and what every fill station on the planet knows how to fill.

The combo valve widens that further. It takes DIN and K-type (yoke) connections, so it fits the rental regulator you borrow at home and the DIN first stage you might buy later, with no adapter and no second valve.

Skip it if you routinely end dives low on gas from an 80. Buying the same cylinder you keep running dry does not fix the problem; a bigger cylinder or better gas management does. Skip it too if you want a technical or mixed-gas setup, because this is a single recreational cylinder at 3000 psi and nothing more.

80 cubic feet at 3000 psi, and 29.75 inches of it

Eighty cubic feet is the number the whole recreational world is built around. Dive tables, air-consumption rules of thumb, boat racks and BCD bands all assume it, so an 80 is the cylinder you never have to think about.

3000 psi is the working pressure, and it is a ceiling rather than a target. A shop that fills to that number gives you the full 80 cubic feet; anything above it is not extra dive time, it is a cylinder outside its rating.

With the valve fitted the cylinder stands 29.75 inches. That is the measurement to check against a tank rack or a hard travel case before you commit, because it includes the valve rather than stopping at the shoulder.

The buoyancy swing is 5.7 lbs, and it decides your weighting

Cyl-Tec gives both ends in salt water: 1.9 lbs negative full, 3.8 lbs positive empty. That is a 5.7 lb change between the giant stride and the safety stop.

The consequence is simple. Weight yourself so you can hold a stop at the end of the dive, not so you sink comfortably at the start. Get that backwards and the end of every dive turns into a fight with a cylinder that wants to go up.

Both figures are stated for salt water. Fresh water is less dense, so in a lake or a quarry the cylinder sits more negative at both ends of the dive and you will want less lead than you use in the sea.

What arrives, and what you do next

The listing is new stock, and the cylinder ships empty because federal law requires an unfilled shipment. So the first stop after the courier is a fill station, not the water.

DOT/TC certification is what makes that trip straightforward: the shop is looking for a cylinder certified to the US Department of Transportation and Transport Canada standards, and this one is. Beyond the first fill, expect the same routine as any cylinder, a current visual inspection sticker and a hydrostatic test in date, or the shop will turn you away at the counter.

The bottom line

A plain, correctly specified aluminum 80 with the one valve that fits everything. If you dive a handful of times a year and rent, the sums take a while to work; if you dive most weekends, this stops being an expense and starts being infrastructure.

The one diver it is wrong for is the one who already finishes an 80 too soon. Everyone else is buying the cylinder the sport was standardized on, and paying attention to two things: the buoyancy swing when you set your weights, and a fill and an inspection before its first dive.

Specifications