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Preflight testing of oxygen systems (and MH O2D2 failures)

Dan wrote:

Since it is more convenient than removing the tubing, I was wondering if there is any wrongdoing by using this method… any takers?

On and off with closed supply works because test will bleed the pressure.

LDZA LDVA, Croatia

Thanks Emir, yes it works pretty good this way, and is easier to do than fiddling with the Festo fitting and release ring…
Still, in the manual it say to disconnect the line after use to release the pressure, so maybe this ON/OFF method ain’t the best?

Dan
ain't the Destination, but the Journey
LSZF, Switzerland

I have never done this.

The regulator valve is normally shut, and indeed shuts when the batteries go flat, too. But it leaks a little bit and after some hours the pressure will be gone. The 1st stage reg delivers about 20psi so when you shut off the main cylinder valve, the pressure will be gone soon.

Otherwise, you can bleed the pressure just by closing the cylinder valve, taking a few sniffs, until the pressure is gone, then switching off the O2D2.

I would definitely not pull the tube out; those fittings are not designed for a frequent disconnect. Well, those going into the 1st stage reg would be ok to pop out, but why? It just knackers the seals.

Administrator
Shoreham EGKA, United Kingdom

Yes, maybe closing the valve and taking sniffs is another good method (less wear on the switch), I’ll try that.

For the checklist lovers, the manual (2019-08-02), page 12 states (my bold):

OXYGEN SYSTEM POST-FLIGHT
1. Turn off the EDS unit.
2. Close the oxygen cylinder valve (leaving the regulator pressurized when not in use can shorten service life).
3. Bleed the regulator and EDS inlet line (see BLEEDING THE REGULATOR, page 8).
4. Stow cannulas/facemasks/tubing to prevent contamination (see STORING THE EDS, page 20).

and page 8 (my bold):

BLEEDING THE REGULATOR
Bleed the regulator between uses. Leaving the regulator pressurized when not in use will shorten its service life.
1. Make sure the oxygen cylinder valve is closed.
2. Remove the regulator outlet tubing from the EDS inlet fitting. Merely removing the tubing from the regulator outlet
fitting of an XCP or FPR type regulator will not actually bleed the regulator as the check-valves incorporated into the CPC outlet fittings will retain pressure in the regulator (also applies to the 6mm Split-Kit, see CONNECTING TO YOUR REGULATOR, p. 16). You may hear the gas escaping as you do this.

Dan
ain't the Destination, but the Journey
LSZF, Switzerland
24 Posts
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