What is the typical sign of a malfunctioning overfill alarm system?

A malfunctioning overfill alarm system is typically indicated by a failure to activate during filling operations. This means that when the tank reaches its set capacity, the alarm does not sound or signal as it should, which presents a serious risk of overfilling. The purpose of the overfill alarm is to alert operators that the tank is nearing its maximum capacity to prevent spills and environmental hazards. If the alarm fails to activate, it can allow the contents of the tank to exceed safe levels, increasing the chances of leaks or overflows.

The other options may suggest some issues with the system but do not directly indicate a malfunction in the way that a complete failure to activate does. Excessive noise during filling operations could be a symptom of other problems, while intermittent signals might suggest a connectivity issue rather than a total failure. Visual warnings on the display panel could be functioning correctly, yet they might not effectively convey the status of the alarm system if the alarm itself fails to trigger. Thus, the clear indicator of an overfill alarm system malfunction is its failure to activate when needed, directly correlating to the safety measures meant to prevent spills.