Each oil tank must be equipped with a device to determine what specific measurement?

The correct answer focuses on the importance of monitoring the liquid level in an oil tank. Each oil tank must be equipped with a device that accurately measures the liquid level to ensure safe operation and to prevent overfilling, which can cause spills and environmental hazards. Monitoring the liquid level also helps in inventory management and ensures that the oil supply is adequate for operational needs.

Maintaining the appropriate liquid level is critical for safety, as it minimizes the risk of accidents associated with overflow or inadequate supply. Implementing a reliable liquid level measurement device can also enhance the efficiency of delivery systems, allowing for timely refills and preventing disruptions in service.

In contrast, while temperature, pressure, and flow rate are important measurements in various contexts, they do not specifically address the immediate concern of managing and monitoring the oil supply in a tank. For oil tanks, maintaining the correct liquid level is paramount for operational safety and efficiency.