I have two tanks next to each other, first needs to be kept at 200 mmHg vacuum & the second at 500 mmHg. Both are attached to a vacuum header which can achieve a 600 mmHg vacuum by means of a water jet ejector. What is the best way to maintain the vacuum levels? Would a set of globe valves work? Or should I have an air bleed / leak? A needle valve? If it matters, the piping is 1". So far without any valves the ejector has no trouble developing 550 mmHg in both tanks simultaneously. The process is fairly static so I'm looking more for an old-school manual solution (that an operator adjusts, say, once every 20 minutes) rather than some fancy PID control loop.