What requirement should all stationary mixers meet?

All stationary mixers must be rated for capacity by the manufacturer to ensure that they can handle the volumes and types of materials being mixed. This rating is critical for safety and efficiency, as it helps operators understand the limitations and capabilities of the equipment. A properly rated mixer guarantees compliance with relevant standards and regulations, supports quality control in the mixing process, and minimizes the risk of equipment failure due to overloading.

The requirement for ratings directly ties into operational effectiveness, allowing for optimal mixing results tailored to specific project demands. Each mixer's rating will reflect the manufacturer's testing and specifications, ensuring that users can trust the performance and reliability of the equipment in their specific applications.

In contrast, the other options do not reflect fundamental requirements that ensure the mixer operates safely and effectively in a production context.