Which device is used to alert users before an overfill situation occurs?

The overfill alarm is specifically designed to alert users when a storage tank is nearing its maximum capacity, thereby preventing overfill situations. This device typically uses sensors to monitor the liquid level within the tank. When the level approaches a set threshold, the alarm activates, providing a warning to the operator. This proactive measure is crucial for maintaining safety and environmental compliance, as overfilling can lead to spills and other hazardous situations.

In contrast, a flow meter serves to measure the quantity of liquid flowing in or out of a system but does not provide a warning about potential overfilling. A leak detector is focused on identifying any leaks in the system to prevent environmental contamination rather than monitoring the fill level of a tank. A shut-off valve can prevent further flow into a tank but typically acts only after an alarm or a specific condition has been met. Therefore, while other devices play vital roles in tank management, the overfill alarm is specifically purposed to warn of impending overfill to ensure safe operation.