We've had the "standard" setup of 2 Becker VTLF 2.250 pumps pulling our Nested 5x12 SCM S15 router at 5,400 above sea level. It's been working fine for about 10 years with little maintenance. Both of the pumps have become louder over time and then started blowing vanes about 6 months ago. One is worse and it took only 3 months to break another set of vanes.
As I start to research them, it seems like dry vane pumps are basically engineered to self destruct over time. The bearings go and the inner cavity just starts to wear and potentially need to be resurfaced. Sounds like 10 years is pretty good for one of these. 10 years at $18k is considered a good thing these days?
The price of Becker parts is insane and the labor to rebuild the pump makes it not really worth it. You can get a Republic manufactured pump that seems to be a direct knock-off of the Becker for cheaper than a rebuild. Maybe I do that and hope for another 10 years?
I don't like the idea of waiting with baited breath for one to break again, so I've been looking at other types of pumps. We don't have the space or the budget for a screw. So I've been looking at claw pumps. They seem durable, low maintenance and pretty well suited for the application. The ideal situation is to replace one of the vane pumps with a claw and keep the other vane as supplemental/ backup. However, I've been told that since the Busch Mink MM 1252 AV claw pump that I'm looking at pulls more Hg's, that I can't run them together because it will essentially pull the guts out of the vane pump? The Claw pump is saying it pulls 29.5 vs the Becker 23.6 Hg's, so maybe the 1 claw pump is enough and we can just keep the vane unhooked as a backup should the claw ever go down.
The other option is to hook the claw to the AB zone where 6' of our sheets reside while cutting and concentrate the vane in the CD zone where the remaining 2-4' of the sheet sits. This may require a new valve to consolidate each pump though.
The final option is to just continue replacing vanes. The generic ones are about $350/ set vs the $1,150 for the Becker branded ones. I can go through a lot of vane sets before paying for a new pump. We are not high production. So, while down time and maintenance time aren't great, they don't kill us.

What about a liquid ring like a Quincy or Travani?

I had a 30HP Sullair for several years. 26 inches vacuum at 400 CFM. Very nice.

I cut a lot of plywood and I find it is the CFM that is the limiting factor, not the vacuum. 26 or 29 inches is really no difference. A 40 HP Travani at operating conditions has almost 10 times the flow than a 10HP Becker.

If you are going to use both pumps make sure there are check valves on the suction of each pump.

I though about that. I'd have to get a water supply over there, but that wouldn't be terrible.
How are those on maintenance?
Size is a bit of an issue. It really needs to fit under my table where the existing ones live. I realize that's not an ideal location, but we're a bit tight on space so it's what it is.

I have two Travaini's for my routers. 40hp. We keep them away from the machines. One in the compressor room and the other in the basement to keep the heat and noise away from the operators. The old one is over 20 years old and still running well with standard maintenance. I'd buy another based on my experience.

We have a 30 hp Kaeser Rotary screw. It is awesome, it snaps warped sheets down. I'd never do a vane pump again. I think CFM is very important.

Good Luck.

Look on Market place in the Detroit metro area I see these pumps come up for sale one in a while my 18 horse Becker has been doin fine for 18 years knock on wood

I Have Travani Dynaseal that came with a shop buy out I did. I dont evn own a CNC but its been in my warehouse for about 12 years Im not sure of the age but looks basically new Would make a very good deal to someone Im located in DAllas area if interested Its a large machine facotry mounted on forklift skods I talked to Travani few years back at IWF and they indicated it was a large one

I have 2 dekker liquid ring pumps .

One with 40,000.00 plus hours

One with 20,000.00 plus

Both still pull hard and run great.

I got rid of my dry vanes right away. I am in Denver and the dry vanes did not pull hard enough at altitude.