SCUBA adapter doesn't tell you tank pressure

[wahoowad]

Forgive me, I'm attempting the absorb all the tank info and am comparing setup costs for SCUBA vs. SCBA vs. industrial tanks. It occurred to me most the setups I see do not seem to have a gauge to show tank pressure, only pressure of the hose side to the gun. How do most of you know the remaining charge in your scuba tank? DO you just rely on how mnay charges you think you have made and then watch to see when you get less than a full charge? If so, crap, my memory ain't that good!

[preez]

Easy, once tank pressure drops below 3000 psi ( assuming that's what you fill to) it won't go any higher than actual pressure in the tank eg.: if you only have 2800 psi in the tank, with the gun hooked up it won't go any higher. Or you can get a blind cap for your hose and open the tank, the pressure gage will show the actual pressure.

Chris

[wahoowad]

Or you can get a blind cap for your hose and open the tank, the pressure gage will show the actual pressure.  Chris

Ahhhh, another new nugget of info to add to the mix. Thanks!

[kiwi]

Unless the tank adapter has a pressure reducer the pressure is the same
in the tank ,  hose & guns air tube.

[wahoowad]

Really? I was under the impression the pressure was less due to a couple different factors....limited opening of the main tank valve, small diameter hose acting as a restrictor of sorts and of course the lower pressure of the gun reservoir as it fills. Otherwise a 3500 psi SCUBA tank would instantly over pressurize a 3000 psi gun reservoir.

[preez]

Not so. You don't open SCUBA tank valve wide. You're suppose to  fill gradually and slowly. If you fill fast you could over pressurize, heat up your guns cylinder (it can get warm while filling) and get untrue reading from your gage, as the air is "unsettled" in the system.  Fill slow, bleed fast.

[kiwi]

wahoowad - 5/8/2010  10:52 PM

Really? I was under the impression the pressure was less due to a couple different factors....limited opening of the main tank valve, small diameter hose acting as a restrictor of sorts and of course the lower pressure of the gun reservoir as it fills. Otherwise a 3500 psi SCUBA tank would instantly over pressurize a 3000 psi gun reservoir.

The size of any opening/hole the air flows though
only alters the fill speed not the pressure..
If the tank you are useing has a higher fil pressure
than the gun then you will over pressureize the gun...
then a presure re-ducer will be needed...
But you can control the pressure with the tank valve
I can get to with in 100psi by useing the tank valve...

Pete

[chugcatsts01]

You need a 'dead head' gauge if you want to do it right. By right I mean often and safely. I bought a quality oil filled guage with DIN to K-Valve adapter for 85 dollars. It has an easy vent feature and can check any scuba tank. I have a 106 CF luxfer with 4350 PSI capacity. Ilive in a divers mecca but no one can get it to 4350. All the local dive shops are just about out of business bcause of the cost of fuel and slumping economy. The cheapest Marina in the area charges $4.00 a gallon for 89 unleaded. The closest 4500 PSI fill is 30 miles away at Tackle Shack, I get my air lines valves and fitting on line.
Halfbreed

[wahoowad]

I have a 106 CF luxfer with 4350 PSI capacity.

I was very close to buying that Luxfer - my dive shop would have put 3900 in it. In the end I found a used 120 for sale and decided the extra 10 fill sin the luxfer wasn't worth the extra 250 dollars in cost. Now I can take my time and look for a second used tank and eventually get a cascade system going.

I'll pick up a deadhead somewhere. Anybody know where I can get one cheap?

[chugcatsts01]

I have been hanging out in dive shops for 30 years. I did not find any good tanks over 100CF when I was shopping [yes I checked all the usual suspects].  The 120 is much bigger and heavier and a new one was $390.00 shipped. In Florida no dive shop is going to give a 3900 PSI fill in a tank rated for 3450/3300. I have have four aluminum 80's. I replaced the freshly hydroed tanks k-valves with retrofit new DIN vales [$39.00 ea]. The burst disks are good for 5250 psi. Tacke Shack wil fill the Luxfer 106 AL to 4500 PSI. Compressed Air Products in Tampa does the hydroes. I have seen the prossess, it gets a 15,000 PSI overfill and the girth or sides are checked with a go-no go guage. I lived on Big Pine Key for a year and a half. The local dive shop fills 2,000 tanks a night on busy weekends and the owner said in twenty years he never saw anything worse than a blown disk or seeping valve o-ring 'ON TANKS THAT WERE MAINTAINED EVEN POORLY.  I have a 'tank balancing rig' that alows me to transfer air from tank to tank. Call Northeast Scuba Supply 919 Trooper Rd. Norristown PA 19403. Their phone # is 610-631-2288. They dont publish an e-mail address. They have 'Dead Head' gauges even cheaper and they look it. Hope that helps you. Shoot straight and keep your air dry.
Halfbreed II

[tat2dman]

Just get a foster male and a quarter inch cap,will be cheaper and acomplish the same thing.........just my .02 :)

[chugcatsts01]

I have done that in the past, but I use my tanks for filling tires, powering small air tools and blow guns. Those tanks are handy to use inplace of heavy air compressors and the CFM isn't too demanding.
Halfbreed II

[kp4att]

To know how much air is in the scuba tank ..... you have to buy an scuba pressure gauge.

/Gerald

[wahoowad]

kp4att - 5/25/2010  12:06 PM  To know how much air is in the scuba tank ..... you have to buy an scuba pressure gauge.  /Gerald

I am confused. Someone above said all you have to do is put a deadhead fitting on the end of the fill gauge and use the fill adapter to tell you pressure?

[kp4att]

is the same!!!

/Gerald