First off, big thanks to Rex Grigg for helping me with the item numbers from the clippard catalog. I would have spent days wandering through their website without his guidance.
I decided a few weeks back that I needed a better way to split my CO2 from a 10 lb. tank to my 29 and 20H tanks that are within 2 feet of one another. before this project I'd been using external "crimping" type air control roller-thingies to adjust the flow to the tanks after the single needle valve and a t-splitter for the airline. it never ever worked right for lots of physics reasons that i won't go into right now. let's just put it this way, if you want to split your CO2 among multiple tanks, you have to use some kind of manifold or adjusting it will be an absolute nightmare.
STEP 1: collect the following materials
2 x 4CQF adapters - clippard
2 x MNV-4K2 needle valves - clippard
2 x MCV-1BB - clippard
4 x 11752-1 10-32 to barb connectors - clippard
1 x 1/4" brass female pipe tee - home depot, etc.
1 x 1/4" brass pipe nipple - home depot, etc.
1 roll pipe thread tape - home depot, etc.
2 good wrenches - garage, neighbor's house, parent's toolbox
45 minutes-1hr assembly time
place two 4CQF adapters into the female tee. thread tape is your friend.
thread the 1/4" nipple into the remaining port on the female tee
thread tee and nipple into the bottom of the regulator (1/4" female port... might have to remove other hardware to get here)
thread MNV-4K2 needle valves into the 10-32 thread ports on 4CQF adapters on assembly.
DON'T FORGET CHECK VALVES! (optional but highly recommended! water in a CO2 regulator can be an ugly thing)
thread 11752-1 barb adapters into both sides of MCV-1BB check valves. don't forget the tiny o-rings on the threads to prevent leaks (included with barbs)
attach airline tubing(silicone, vinyl, nylon, flexible pvc, polyurethane, flexible copper, etc.) to barbs on check valves, needle valves, and CO2 diffusion devices.
**Please be sure that the arrow stamped on the check valve is facing with the direction of CO2 flow, or your setup won't do anything except blow the airline right off the check valves and/or needle valve barbs.**
When placed properly, you should never even know the check valves are there until you lose pressure in the CO2 tank, at which point no water will be able to siphon back into the airline from your CO2 diffusion device.
I hope this helps some of you in one way or another. total cost for the setup was... $50 for clippard parts (including check valves and barbs), $4 for home depot parts. the things about this setup that are most attractive to me are
#1 I built it myself (so all leaks, poor connections, etc. are my fault)
#2 comparable in price to inline manifold systems from websites
#3 better suited for the pressures than inline manifolds, which require a run of tubing *BEFORE* the needle valves, meaning there's some airline tubing under serious pressure, and likely to lose some gas.
#4 includes quality check valves in the price, where the inline models, etc do not. most of them sell CO2 check valves for $10-$15 each. once this is considered in the price, this is a bit cheaper than buying online.