Final answer:
Mechanical float devices, electronic shut-offs, and scales can be used to ensure that recovery cylinders are not filled above 80% capacity.
Step-by-step explanation:
To ensure that recovery cylinders are not filled above 80%, several methods can be utilized for monitoring the fill level. These are: mechanical float devices, which physically measure the level of liquid inside the cylinder; electronic shut-offs, which use sensor technology to automatically stop the fill when the level reaches a certain point; and scales, which measure the weight of the cylinder and its contents to determine when it is 80% full. These tools help maintain safe operating conditions and compliance with regulations.