gasses -- compressed gas cylinder and tank information

Disposable propane cylinder threads are usually 7/16th UNEF. In addition there is an automatic valve in the fitting activated by a pin inside the female fitting. Simply screwing a hose with a 7/16th UNEF fitting will not allow you to use the bottle. The fitting with both the threads and pin are called Type 1 or QCC-1 fittings. Don't expect even sales people to know this.

Medium cylinders use Acme threads Large cylinders (>40 pounds) use NO, I think this may be wrong. My notes are unclear. Double cheek and correct 1"-20 UNEF threads (called POL threads)

• Outlet threads: 1"-20 UNEF
• Inlet threads: 0.880-14 NGO-LH-EXT

1-5/16" Female Acme Inlet

1/4" male NPT

CGA

Compressed Gas Association

CGA870

post valve fitting often used in O2 for human use (medical, supplemental).

CGA540

valve fitting used for O2 regulators in welding

CGA300

valve fitting used for acetylene regulators in welding.

Propane 1 pound disposable threads

1"-20 UNEF threads? Need to check this.

Propane 40 pound tanks

POL

Welding O2 vs. Medical grade O2

Most compressed gas suppliers will have a large dewar bottle of O2 that they use to bill both medical grade and industrial grade O2 tanks. It's most likely safe to breath from industrial grade O2 tanks, but the supplier does not have to promise that. Medical grade O2 tanks are also designed and made differently and have different standards and requirements for inspection. Medical grade also often requires a dive license or doctor's prescription to purchase. It may seem silly, but don't argue with the gas man. The rules are complex not just to annoy you. It's a simple matter to attach a medical fitting to an industrial tank. Bring that setup to be filled and you may be refused. You can buy or make an adapter... In my case, I wanted to use medical tanks for industrial applications. The gas supplier may be more tolerant of this. You can find a greater variety of sized and weights for small medical thanks. The smallest common industrial tanks for 20 cubic foot steel, which are not huge, but are still 15 pounds. While you may find a gas supplier to fill your bottle they may simply not want to. It's as much effort for them to fill a 20 cubic foot tank as a 125 cubic foot tank. It's not so bad if you lease a thank and simply exchange them. They fill a big batch of the little tanks all at once. But you can't do an exchange with a weirdo, custom bottle. They would have to fill it while your wait. A saner approach would be to lease a big bottle of oxygen. Take it home and use it to transfill your little bottles. You can find transfill adapters for this purpose.

In practice, it's no less expensive for a gas supplier to store and supply industrial grade O2 than medical grade O2. In reality they may charge you more for medical grade O2. Don't argue with them. If you're so smart then just guy industrial tanks and breath that.