[w ripley]

With my Meg I used a Meg O2 Calibration Kit, which was fast and didn't use much O2 in the process. Because the HH's head is similar in design, I made a similar O2 Calibration Kit for it.

The way it works is to allow O2 to enter in one side of the O2 sensor cavity inside the HH's head and to reduce the exit flow of the O2 on the other side of the head. Then, while the sensors are awash in O2, you calibrate your handsets. The nice thing is that you don't need to fill your loop, canister, or counterlungs in the process, just the O2 sensor cavity.

My cost was under $5.00 USD, and the Meg's kit lists for $63.00.

The first picture shows an exploded view of a Gilmour garden hose quick disconnect set with washers and one extra male disconnect end piece. Everything came from Lowes. I removed the washers just in case they would be a fuel source for the O2. I also bought a duplicate set of everything and cut it in half, just to make sure there was no rubber or other fuel source inside. There was just the plastic that everything is made of and two metal springs inside.

Next, in the second photo, I found an old oxygen analyzer that no longer works and pirated the connection hose which had a brass hose fitting on one end. I figured the hose would be O2 safe, as would a piece of clear plastic hose. You do need some way to connect this hose to your O2 supply hose, but it doesn't have to be fancy. Also, you don't really need a flow restrictor as you can control the volume of O2 thru the hose by opening or closing your first stage valve. Nothing was done other than to insert the connection hose into the end of the one male quick disconnect fitting.

In the following photos I put a piece of "white" tape around the "exhale" fitting on the HH's head and around the bottom fitting of the head where it goes into the scrubber, to make seeing everything hopefully a little easier.

I tied a piece of string between the two final pieces of the kit so that I could keep them together and, more importantly, so that I would have something to remind me to remove the fitting on the exit side, before attaching the head to the scrubber. Wrong place to have a reduced-flow fitting. The Meg gets around this by using a "cap" vs. a "plug" on the exit side.

Hope this is helpful. It really works.

Regards,

Bill

[w ripley]

Correction: The post should read as "inhale" side, not "exhale" side.

Sorry,

Bill

[Deepdiver]

Bill,

What a great idea, thanks for that I will be doing the same thing when I get mine....

[w ripley]

Nick:

Thanks for the comment. It's all in the way you like to calibrate your unit. I like doing it this way and appreciate Kevin and Jakub setting everything up so that a hose part from Lowes would fit perfectly.

Glad to see you've finally decided on the HH. Mrs. T should feel better with you taking it to Mount Gambier.

There is also a nice DIVA mod that I will pass on to you in a PM.

Regards,

Bill

[Deepdiver]

Bill,

Thanks I will look forward to that.

[Skipbreather]

Hmmmmm. Gives me an idea. Of course, I'd have to get my hands on an HH lid for a few days...........

[mdsourou]

I bet you ge an idea of this Ken . You always get ideas
Very expensive calibration kit Bill

[smokey]

Whats the HUD mods share the news pls,

Slight mod some electrical tape around the stem makes it easier to see.

[MarcLaukien]

Here is my calibration kit. It consists of the following:

• 1/4-Inch NPT to BC inflator. You can get this for example from Rebreather Express.
• Brass Flow-control Orifice With Pipe Thread, 1/4" Male X Female, 0.016" Orifice Diameter (McMaster 2712T489).
• Brass Double-barbed Vacuum Tube Fitting, Adapter For 1/4" Tube Id X 1/4" Nptf Female Pipe (McMaster 44555K125)
• Viton Rubber Tubing, Soft, 1/4" Id, 3/8" Od, 1/16" Wall, Black (McMaster 5119K43). You could probably also use a cheaper tubing, since it's low pressure O2.
• Tapered Push-in Round Rubber Plug, Solid, Size 9, Fits 1-25/32" Large End Id (McMaster 9545K22).
• Sullivan Fuel Elbow Large, from Tower Hobbies. You can of course use something else instead, like a simple brass tubing. I just happened to have one of these in my workshop. Drill a hole into the rubber plug, and push the elbow or tubing through the hole. Make sure to clean the plug properly, so that no rubber residue gets into your canister.
• You also need Teflon tape for the seals, and some cable ties to secure the hose.

I simply plug the calibration "tool" into the O2 manual diluent addition hose, and the rubber plug into the inhale side of the canister (because the inhale side is closer to the sensors). I leave the exhale side open. With the scrubber already in the canister, it will take a few seconds until the O2 reading is stable. It doesn't take more than about 0.6 to 0.7 cf to calibrate.

[Shaunzxr]

Out of interest how often do you calibrate your sets
Thanks

Quote: (Originally Posted by MarcLaukien)

Here is my calibration kit. It consists of the following:

• 1/4-Inch NPT to BC inflator. You can get this for example from Rebreather Express.
• Brass Flow-control Orifice With Pipe Thread, 1/4" Male X Female, 0.016" Orifice Diameter (McMaster 2712T489).
• Brass Double-barbed Vacuum Tube Fitting, Adapter For 1/4" Tube Id X 1/4" Nptf Female Pipe (McMaster 44555K125)
• Viton Rubber Tubing, Soft, 1/4" Id, 3/8" Od, 1/16" Wall, Black (McMaster 5119K43). You could probably also use a cheaper tubing, since it's low pressure O2.
• Tapered Push-in Round Rubber Plug, Solid, Size 9, Fits 1-25/32" Large End Id (McMaster 9545K22).
• Sullivan Fuel Elbow Large, from Tower Hobbies. You can of course use something else instead, like a simple brass tubing. I just happened to have one of these in my workshop. Drill a hole into the rubber plug, and push the elbow or tubing through the hole. Make sure to clean the plug properly, so that no rubber residue gets into your canister.
• You also need Teflon tape for the seals, and some cable ties to secure the hose.

I simply plug the calibration "tool" into the O2 manual diluent addition hose, and the rubber plug into the inhale side of the canister (because the inhale side is closer to the sensors). I leave the exhale side open. With the scrubber already in the canister, it will take a few seconds until the O2 reading is stable. It doesn't take more than about 0.6 to 0.7 cf to calibrate.