Pics of Biopak center section mods

S. Marc

To do this mod took a lot of thinking, very little time, and one previously abused and cracked center section. I wasn't going to do this with a good Biopak, if such a thing exists

Used 2 " diameter PVC rod that I turned, bored and then milled to friction fit the holes I drilled in the center section, and attached the two fittings with multiple layers of good quality 2 part food grade epoxy.

To drill the center section I used my milling machine with a 1 1/8 " forstner bit (I think that is what it is called).

Cutting the center section cleanly required some experimentation. I found that to make clean cuts, a red hot thin exacto blade / utility knife / box cutter worked well, so long as you cut quickly to prevent bubbling or distortion, and cleaned the blade before re-heating for each cut.

This mod was done to my spare center section that is damaged and will likely never be dived due to a crack. I have not taken the time to pretty it up, but the epoxy wet sands very well and could, with some elbow grease and the use of a mcu better machinist that I, almost look like an OEM feature.

I tested counterlung ADV activation after the mod and it does activiate well at all. Will need to remove some of if not all of the plexi disc to allow counterlung to bottom out on the ADV as it is coming into contact with the PVC fitting (as I knew it would - actually didn't think about it at the time I did the mod) .

Will have to think about modifying the lung as the counterlungs are hard to find and I need the ones I have for another project.

If I modify my other center section, the one without cracks, I will likely machine threads onto the inhale and exhale tubes to allow attachment of different hose diameters using adaptors.

I plan on using the original port to attach the PPO2 monitor cable gland ( I use sealcon connectors on my other homebuilt). Just need to machine a piece of PVC and epoxy in once tapped for the fitting. I found that Delrin does not bond well with this epoxy.

Any suggestions or comments on how to do this differently (read - Better) would be appreciated.

Pics follow

rdmmdr

nice work marc, but why the split between to inlet and out let.
rick

Sandy

Tidy work. Looks like someone has access to a machine shop. Not to sure if I can see the perspective right but will your new port interfere with the auto addition valve? or perhaps you're not bothering with using it as an ADV.
Cheers,
Sandy

Sorry. Got carried away looking at the pics and missed your text. you've taken care of it.