I like the idea of the 4 valve manifold because you don't have to remove a hose to switch from evac to charging. I worry about the vac being lost or compromised at that point.
I have a JB Hindenburg 4 valve manifold with big vac line but it is so heavy and cumbersome. I would like to get rid of it and use a YJ 41 brass 2 valve unit. (My favourite gauge set is the brass yj 41232 with the class 1 brass gauges.) It is light weight and feels and looks right. But I am still worried about that hose change. Even if you have ball valves on the hose, there is still a part of the fitting that is exposed to atmosphere when the valve is closed. I like the idea of evacuating the charging hose before putting freon in it, like you can do with the 4 valve. Of course you can purge the air out of the yellow hose by removing it from the manifold and filling it with freon, but then you still have the little space inside the manifold that didn't get purged, and was exposed to air when the yellow hose was removed for purging. Then when you start to charge, all the air that got in the manifold will be forced into the system! a 4 valve would fix these problems but I am wondering if there is a way to do it with the 2 valve.
I had one idea for the 2 valve manifold, which was to run the yellow hose to the vac pump with a tee fitting on the vac pump, with the branch fitting of the tee attached to a hose going to the freon tank. That way you could evac the freon charging hose. You would have 4 valves then, except one of them would be on the freon tank and one on the vac pump. Is this a good idea? Am I worrying for nothing? Is there a better way to use a 2 valve manifold? Does anyone use 2 valve manifolds who can tell me a better way to accomplish a setup that will not allow any atmosphere to get into any of the hoses or the system? Or is there some problem with my idea, and I am just going to have to lug that Hindenburg around until I can get one of Doug's paradigm manifolds. I would like to get this figured out because I can still return the hindenburg to johnstones as I haven't used it yet. I read that JB brass manifolds can be outfitted with 3/8 vacuum line ports and used with 3/8 line for the yellow line to increase flow to the level of their hindenburg manifold. I might rather have one of those but I haven't tried them. Could always put the yj class 1 brass gauges on that.
whichever manifold I use, I still use appion core removers with shutoff valves on the high and low side access ports, and I close them to check if the system holds vacuum. Micron gauge on the side fitting of the core remover with a stainless hose.
So I don't have to worry about my hoses absorbing atmosphere when I am testing for leaks and moisture, because the hoses aren't in play during the test. I would like to be able to start charging the system without compromising this wonderful vacuum that I spent all this effort creating.
Any ideas or input is appreciated.
Oh sorry...they call the jb 4 valve the Zeppelin, not the Hindenburg. sorry about that. wrong blimp. It does look just like the hindenburg though.