Vacuum pump A/B manifold - good or bad idea?

tdotrob

T.Rob
Corporate Member
I am currently running two vacuum chambers in parallel. One is stabilizing some burl and the other is drying half a log. Every time I switch from pulling vacuum on one chamber to the other, I swap hoses at the pump. So I thought, why not buy or make an A/B manifold? It would be a 1/4 female flare into a tee with two valves and two male 1/4 flare fittings.

Of course, there are some possibilities for things to go seriously wrong such as flipping the wrong valve and evacuating all my pump oil into one of the chambers. Or possibly something more subtle such as more places for leaks, or maybe the manifold placing too much torque on the pump fitting and causing metal fatigue or seal degradation over time.

What is considered "best practice" here? I can see an argument that the manifold introduces more problems than it solves and I should just keep swapping hoses. If an A/B manifold is a good choice, next question is whether a newbie can reasonably expect to get it to seal when building it from components.
 

JNCarr

Joe
User
I currently use a simple vacuum bag for veneering, so dont need a manifold - BUT - we used to do this all the time at my previous company. We're not talking about 10-9 to 10-12 Torr (I spent 25 years in the semiconductor industry) but a relatively soft vacuum, so standard brass fittings, valves and PE tubing should work fine. Since you are on the draw side of the pump, I dont understand your concern about backflowing pump oil into one of your chambers (??). Maybe a schematic would help.
 

tdotrob

T.Rob
Corporate Member
Since you are on the draw side of the pump, I dont understand your concern about backflowing pump oil into one of your chambers (??).
That's the main thing warned about in the manuals, videos, etc. "Never expose the pump to vacuum when it isn't running." With two chambers there's more opportunity to muck it up while one of them is under vacuum and the operator is focusing on the one that isn't.

So why am I worried this about it? Professional hazard. When I'm not in the wood shop I do IT security consulting for a living. One aspect of many specialties, including mine, is "anti-patterns." These are things that should never be done but seem to be irresistible to newbies so end up being implemented all the time. The results can range from merely counterproductive (doesn't fix the issue, engineering cost wasted) to catastrophic (company folds).

When it comes to vacuum chambers I'm that newbie. What I am considering seems intuitively obvious but I know next to nothing about vacuum systems so I thought I'd ask and see if it's an anti-pattern. Maybe the experienced folks would chime in and tell me "mount the manifold on a hose, never on the pump" if there are structure fatigue issues, or "people always get the valves mixed up and blown pumps are more common than you'd think." Or something completely different, I dunno.

"You are seriously overthinking this" is actually the answer I was hoping for when I posted.
 

Phil S

Board of Directors, Events Director
Phil Soper
Staff member
Corporate Member
Ok
Some rules
Don't put your hands too close to spinning tools
Don't touch tools just off the grinder
Don't overthink simple solutions - your A/B manifold is a good example, just build it
 

tdotrob

T.Rob
Corporate Member
your A/B manifold is a good example, just build it
Thanks! I'll give it a shot.

Cant you simply put a valve on each line?
Each chamber comes with it's own valve and hose. The problem I'm solving is that the pump accepts only one hose at a time. So, yes, attaching an A/B manifold to the pump pretty much boils down to putting a valve on each line, it's just that they are combined into a Tee fitting.

The main difficulty I have with your suggestion is, I'm a software engineer and autistic. I don't do anything "simply".
 

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