Your using scuba tanks. Use a scuba regulator. The first stage pressure is about 150 psi and could be adjusted if you need to, which you probably don't. They are made from plated brass. Stainless is often not suitable in salt water.
Compositepro,
Just curious, how do you know he's using scuba tanks? Good point about the stainless, at 3,000 psig I'd be nervous about Chloride Stress Cracking in sea water.
Yes i am using scuba tanks, good guess! I looked at scuba regulators, but need something with 1/4" connection, was hoping to find something more "industrial"
The most popular scuba tanks are aluminum, since they form an aluminum oxide coating which prevents further corrosion; internal inspections are still legally required every year, hydro every 5; and are more buoyant than steel tanks. The disadvantage as a diver is that they shift from neg to pos byoyancy as they become depleted, but that does make finding them after they fall off the boat much easier, as well as those unfortunate divers that run out of air. Tanks are marked 3AA or 3AL. 3AA is the marking for chrome-molybdenum "Stainless" steel, of which both 304 and 316 are used. I'm sure you've figured out that 3AL means aluminum.
By industrial, I take it you mean cheaper? Most scuba equipment is more expensive and have a more flashy finish than their industrial grade counterparts.
Instead of SCUBA tanks the issue is more like the regulators for low volume gas. Many companies make gas regulators suitable for the pressure drop.
My billet example was 3000 psig brine from cavern development for injection into a disposal well with unknown drop. The valve was made by Cor-Val (Now T3 Energy) but Fisher sells Cavitrol trim for simila valve applications. Masoneilan, Valtek and others can also do this. Several cavitation control trims can handle such drop with a clean fluid.
I don't see where 316 is a problem, given adequate inspection and maintenance, on the other hand, a cheap valve, maybe. Cheap is a rather subjective term, not to mention that cheap and offshore, especially submerged and controllable, don't go together well.
Try TESCOM, they make gas regulators for high purity gasses, go to really high pressures, and have stainless as well as some exotic metals. however, I am not sure they have enough flow!!
