: Hi fellow gizmologists, Shawn and Charles

Gizmologists? Hmm. Well, we're both zymologists Does that description fit you as well?

: I have made a few of these pumps, also with modifications.

A few of these? I knew it! After the first one, well, I just want to improve the efficiency!

: The 90 degree elbow will increase piston travel ie volume of the pump and have
: less resistance because the exit diameter is the same as the pump diameter.

Ooh... Interesting... I might be persuaded to try something like that - when I find some lighter pipe! (Right now my main pipe is schedule 40 - way overkill for the job!)

: Oh and one more thing, I tried different materials for the flapper and
: plunger valves and ended up using flat neoprene discs that I cut from an
: old dry bag. The flattness is critical to getting a good seal.

I switched to using some sturdy vinyl fabric for the same reason.

: I could get some photos in about a week if that would help. This is fun stuff,
: hope you are enjoying the process.

It started getting fun about the time that it started working! Now, I've just got to make it fantastic...

cheers!