Calibrating a zahn cup

[Len]

After using a plastic Zahn cup for a while, I suspect that a small amount of residue in the outlet hole will change the timing on the cup. Does anybody know how long it takes for clear water to empty from a new one of the popular plastic cups?

Len

[woodchucker]

Technical Data Cup Number Seconds Range Centistoke Range Midrange Sensitivity¹ Calibration Oil Number²

1 40 to 60 10 to 36 1.3 G-10/19 2 20 to 60 19 to 156 3.3 G-60/117 3 12 to 60 64 to 596 10.5 G-200/458 4 10 to 60 79 to 784 13.9 G-200/458 5 10 to 60 161 to 1401 24.2 G-350/878 ¹ Stated as centistokes per second of efflux time. ² Centistoke values are nominal - actual values printed on labels