Nitrox Membranes

[pescador775]

You can't insert a membrane between the first and second. The second stg will not like being fed mix at atmospheric pressure. The NITROX stick is ridiculously easy to build. Just buy a piece of 2" PVC pipe, some caps and other small fittings and you're in business. The idea is to interfere with the flow of air and O2 to cause mixing. The Hacker way is to make up some "simple" baffles. I use wads of stainless steel spun ribbon (abrasive pad called a "steel sponge" , no 725 made by Gottschalk). Use screws to keep the pads from moving, although it is a tight fit anyway.The intake is just a Coltri remote intake with 1/2" npt available from Compressed Air specialties. Drill and tap the cap and screw in the intake filter. Install a foam sponge under the four abrasive pads to trap any possible metal particles. This is packing foam or upholstery foam.
Pesky

 

[StSomewhere]

For Continuous blending you need a means to control / meter the O2 entering the mixer, and a means to measure the percentage O2.

But for either continuous blending or partial pressure wouldn't I still need a source of better-than-Grade-E air?

 

[cool_hardware52]

But for either continuous blending or partial pressure wouldn't I still need a source of better-than-Grade-E air?

One the huge benefits of continuous blending is that Modified grade E air is not necessary, and O2 clean cylinders are not required.

Why you ask? Because you never have Pure High Pressure O2 in contact with anything after it leaves the O2 supply cylinder and regulator.

The O2 is delivered into the Mixing stick at very low pressure, barely above ambient. The resultant mix leaving the compressor 40% or less, often no more than 32%.

When partial pressure blending Pure O2 is decanted into the scuba cylinder. This puts Pure High Pressure O2 in contact with the fill whip, scuba valve, and tank.

The downside of continuous blending is the risk of fire or explosion in the compressor, and the risk that oil or Hydrocarbons may flash and produce toxics including CO. This "flashing" can occur without the operator being aware of it.

All things considered, for the owner and user of the scuba cylinders, continuous blending is a lot less work, no O2 cleaning for 40% and less.


Tobin

 

[san diego diver]

well
, i've finally built the blending stick,i used the oxy hackers handbook (great stuff !!) and bought the O2 analyzer and sensor from OXYCHEQ it cost 340.00 but it was complete with everything i needed for that part of the system. after i put it together i went to the welding supply store that sells aviation grade O2 and they wouldn't sell it to me until i have an interview with the owner this afternoon to see if i understand the dangers of O2 !!! WHATEVER !! I guess they are concerned about liabilaty because one of our local tec divers was using thier gas when he died on the Youkon.
(even though he died because of entangelment issues,) i will let the thread know how this interview goes later !!