You are planning to use a crude oil washing system. What precaution must be taken with the source tank for the washing machines?

Correct Answer: Option C — At least one meter must be decanted from the source tank.

Under 33 CFR 157.138, the source tank providing oil for crude oil washing must be decanted by discharging at least one meter of liquid depth before use. This removes any accumulated free water at the tank bottom, preventing water-in-oil emulsions from creating hazardous electrostatic discharges inside the tank being washed.