24$ o2 pp blending whip idea

[northernone]

Good day,

Looking for some experienced advice on a project. Building a portable, compact and inexpensive whip to do partial pressure blending for nitrox.

The concept is using my o2 cleaned first stage and HP port to deliver a metered flow from the cga 540 with a check valve on route.

Using my analyzer over the course of a few mixes I can determine the flow rate of the hp port and then simple do timed fills for my blends. There by eliminating the flow valve and pressure guage while still having a degree of accuracy.

New parts list:
-CGA 540 brass nut/tailpipe to male 1/4"
-1/4" female to Male JIC Thread 7/16-20 In

Regulator parts (o2 cleaned):
-Hp hose standard JIC Thread 7/16-20 In (spg removed)
-1st stage
- 2nd stage regulator and lp hose (as whip bleed valve)

I'm hoping this will be more accurate (with practice) compared to blind blending, but either way I'm willing to adjust my dive plan to match my analyzer gas anyway.

What haven't I thought about?

Cheers,
Cameron

 

[Peter69_56]

Is your issue metering the flow? I am a bit confused as to how you are trying to do this?

I have a standard whip for cylinder to cylinder transfer

For PP blending I have a medical cylinder with medical attachment, a HP needle valve at other end a NRV, DIN attachment with bleed valve. All basic but all Oxygen clean and 200 BAR rated. Needle valve is SS. All fittings SS or brass

Sorry just re-read your post clearly its cost?

 

[northernone]

Good day!

Thanks for having a go at my ramblings post. Sounds like you've put together a functional whip.

I'm looking to build this pp blending whip using mainly parts I already have. You are right about the metering of the flow being my main issue.


With your setup is there a gauge involved and also is your hp needle valve opened and closed each fill or left permanently cracked open as a restriction and you use the tank valve to start the flow?

Cheers,
Cameron

 

[tbone1004]

first stage HP ports only flow about 3.5cfm. That is a LONG time to transfill anything.
http://www.piranhadivemfg.com/item/Din-Cylinder-Transfill-Hose--1046

That is what you really want, and it's not all that expensive. If you're PP blending, it's a lot easier than dealing with a first stage. I can't imagine that it's good for the regulator to have O2 going out of that small of an orifice after it goes around lord knows how many bends.

 

[Peter69_56]

I actually have 2 needle valves and 2 gauges (bit of overkill on valves).

I have the tank valve but turn that on, next valve is needle valve to throttle, down the pipe to second valve (full open unless i check tank pressure first) then pressure gauge and fill tank. I open and close the throttle valve each time no prob.

 

[Peter69_56]

I would say though that my hose is oxygen hose and not just a HP hose. The piranah dive hose has steel fittings (as I have one). I dont use it for PP blending, just transfill. My rig is all oxygen hose, SS or brass. Also I can quick disconnect/connect my oxygen booster pump to this setup for boosting if required.

 

[northernone]

The bends can be dangerous above water too! Good reminder, I was concerned the 1st stage would heat up the o2 too much.

Sounds like a good build. And thanks for the heads up on the transfer whip too! It certainly addresses my need for a portable inexpensive solution. Somewhat less satisfying without the DIY component but gets the job done when I'm at a remote site.