I'll simplify my real question: what is recommended practice to distribute a limited amount of compressed gas to several systems such that a leak in any one system does not depress pressure in all systems?

(A) pressure regulators set lower than supply pressure?
(B) check valves?
(C) intentionally add small ID pipes between manifold and systems to restrict gas usage therein?

We are in the process of adding pressure transducers to each system, so we can determine which one is at fault. But I need to also prevent.

Background: I'm in a facility and at some point we had the bright idea to feed multiple systems via nitrogen instead of air compressors. We already had liquid nitrogen tank & evaporator, for blanketing oil farm tanks. This was regulated down to 100PSI and fed via 1" pipe and then (alert: bad idea), someone selected small ID lines between end of 1" pipe, to 90PSI regulator, and then back out to a manifold. From manifold, all systems' pipes are back 1". Currently, a leak (or abnormally-high flow rate) in any ONE system depresses systems pressure in ALL systems, causing air-operated valves to fail to open completely. Ask me how I know...