$$t = \fracVQ_s \times \ln\left(\fracP_aP_a – P_v\right)$$
Have a specific application? Drop the specs (part size, material, cycle time) in the comments, and we will run the numbers for you. vacuum ejector calculation
But here is the common pain point: An undersized ejector leads to dropped parts; an oversized one wastes massive amounts of compressed air. Example: You have 1 liter of total volume
Example: You have 1 liter of total volume and a suction flow rate of 100 L/min (1.66 L/sec). $$t = \frac11.66 \times 2.3 \approx 1.4 \text seconds$$ cycle time) in the comments
$$Q = 13.2 \times d^2 \times (P + 14.7)$$
$$Q_s = Q \times C_v$$
Vacuum technology is the silent workhorse of modern automation. From picking up a silicon wafer to lifting a heavy cardboard box, vacuum ejectors (also known as vacuum generators) are the devices making it happen.