MLT Bulkhead/Ball Valve Configuration-I know how, but why?

Okay, so I know how the major commercial manufacturer Zymico configures their weldless fitting for MLT's, such as Kewler Kits:


So I know all this and I will probably follow suit as I'm getting my AG equipment together now, but I want to know why they go from 3/8" diameter on the inside of the tun to 1/2" on the outside? Why not stay either 3/8" or 1/2" all the way through? I have searched the forums and there's not a clear answer to this particular question here (that I found).


After looking at putting my own fittings together, I have a guess....how about availability of certain sizes?
No, because that doesn't explain why there are MORE sizes involved.

Does it have to do with the flow of the liquid out of the tun?
No, that's why there's a ball valve.

Matching up the tubing size of the sparge arm?
Hmm, can't find tube specs on spargers...

Matching up the barb size of the false bottom?
Yep, 3/8" for all false bottoms.

The big fat barb on the outside looks cooler?
Ahem, I'm sure everyone would like a larger barb...

Am I reading too much into this?
Wouldn't be me if I didn't research to death!

You can really go crazy putting one of these things together!


Anyone know for sure? Does it matter?

Thanks!
:cross:

A. The only way you'll get an answer is to ask Zymico.
B. Tradition
C. Doesn't matter
D. If you DIY, use what suits.

Another guess: if the inner pipe is smaller than the outer pipe, nothing that gets into the assembly will get stuck on the way out.

Wouldn't it create more suction if the outlet were bigger than the inlet? Perhaps that is the reason.