Fabricating Airlock/ Blow Off on top of a 3.5bbl Plastic Conical

[bluewaterbrewer]

I just got my 3.5bbl plastic conicals in and need some advice. I am looking for the best way to mount a 1.5'' TC to the top of the black screw lid so that I can attach a 1.5'' TC x 90 elbow/hose barb for a blow off tube. The black lid currently has some sort of PRV that moves up and down. I want to take this part out and replace it with the TC.

Any ideas as not to ruin the lid? Anybody got any pics of a similar project? I thought I had remembered seeing some similar designs on here in the past but I cant seem to locate them.

Any help would be appreciated. I have the rest of the fabricating down. This is the last step to completing the fermenter and Im getting a little ancy, but I want to wait and make sure I dont screw up a $400 piece of plastic.

Thanks in advance,

[Starcat]

Tank Adapter

You should be able to use a tank adapter with FPT threads in the port opening. Then get your TC fitting with the same MPT size.
Make a clean cut with a hole saw for the adapter. You will have to be able to reach both sides to screw it tight.