Here's my version of the PVCBVDSV:



It's a 1" PVC ball valve, drilled axially to accept a 3/4" PVC pipe (thinwall!), heated and shaped to an oval to fit a standard mouthpiece. Valve body is bored out to fit the mushroom valves from an Interspiro quasi-AGA mask (included with the BioPak 240 "rebreather kit"). Is the 7/8" bore of this DSV too small, considering the rest of the loop is 1-1/8" and greater diameter? Probably, but then again, where is the smallest restriction in the loop? I'd guess it's the gap between your upper and lower incisors as you grip the mouthpiece. In-depth dive report to follow.

I'm almost afraid to show pics of my homebuilt BOV...

-Dan