Sorry to say this, but your fundamental concept is a bit off. The machine is already threaded with about 1 mile or more of film support (that is 72" x 5000 ft at Kodak Park). The hopper is running with the many layers of the film substituted by water at the coating temp. The emulsions, overcoats, undercoats and all begin feeding and a stable bead is established in the light and then they go dark. Meanwhile the coating machine (support) and the feed pumps are ramping up to operational speed and then they go dark and run until that job is finished.
A typical kettle can contain from 10L (Research) to 50 - 100L for prototyping up to 1000L for some applications.
Silver in most films run about 3 grams per square meter or more. That is a very rough approximation.
The coating machine is left threaded with film after the job. Rethreading a mile of film support is a job you do not want! Never let the machine run out!