Final answer:
The fill level of a cylinder during vapor recovery can be controlled by mechanical float devices, electronic shut off devices, and weight. All three methods ensure the cylinder is filled to the correct level without overfilling.
Step-by-step explanation:
When using vapor recovery, the fill level of the cylinder can be controlled by mechanical float devices, electronic shut off devices, and weight. These are all mechanisms used to ensure the proper fill level is achieved without overfilling the cylinder. A mechanical float device works similarly to the float in a toilet tank, rising with the liquid and triggering a shut-off when a certain level is reached. An electronic shut-off device uses sensors to detect the level of the liquid and signals the system to stop filling when the appropriate level is achieved. Lastly, using weight as a control means placing the cylinder on a scale and monitoring its weight, filling until the desired weight, which correlates to volume, is reached. All of these methods are essential in managing vapor recovery efficiently and safely.