Balancing Vacuum or Air

You may need to supply more info to get the answer you need. However, if you want to make the vacuum level (in inches of Hg, for example) at each port equal, that will naturally occur. If, for example, you are pulling vacuum on 16 bell jars, they will end up equally evacuated, given time. On the other hand, if you are concerned about the time required for evacuation, then flow rate through the manifold and all piping, etc., becomes an issue. The flow rate will depend upon the number of restrictions, piping length, volumes to be evacuated, etc. If you can keep the number of sharp turns equal and the distances and piping sizes equal, the flow rates will be relatively balanced.

If the piping is complex, and the need for equal flow rates is critical, then modelling in a CFD program would be worth considering. If the application is not so critical, putting flow controls in each of the 16 lines would enable you to do flow balancing empirically.

I may have misread your post: If your block is working as a gripper, rather than as a remote manifold piped to individual grippers, then most of what I said is nonsense.

You need to place a restriction in each vacuum channel so the vacuum source is able to keep the vacuum plenum at the required vacuum. That means the capacity of the vacuum pump must be enough to tolerate the leakage through 'n' uncovered ports.

You might have 60 ports and if you clamp a small item covering, say, 6 ports, then 54 will be hissing at you and reuining the vacuum....unless the pump can keep up.

You could cover the uncovered ports with a small ballbearing for each one and you can magnetize them to control them. Just sweep them out of the way, plant your object and move the balls to cover the holes not used. If the machining noise is such that you cannot hear the hiussing and the pump can keep up, no need to block the unused holes.

There is not much need for high volume flow through each hole as it will be normally blocked by a flat, so a tiny hole is all you need/ You will also need a way to back blow the hole in case they snort in something that blocks them

I saw a neat home-made vacuum table for clamping wood, the table had hundreds of little balls just protruding from the surface of the table. the 'suction' was delivered to the 'top' of each ball by series of little holes. (square holes at that...work it out) when a block of wood was placed on the table the balls were pushed down and the block was clamped. all the unused balls kept the vacuum nice and tight.

You can just build the thing and see what your vacuum rates are at each of the 16 areas. You might discover that it might be so insignificant not to even worry about.

But if you want some ideas your block have vacuum pulled from all 16 areas

or

have a continuous tube with smaller holes bored in the pipe at the vacuum pads.

or

You can also use a porous plastic sheet over some type of pan.

or

Our you can talk to some people who use cnc machines for wood working and see how they do this. They might work with flip pods.

good luck