Warning systems should be installed to detect abnormal conditions, malfunctions, and incipient failures. An alarm system (consisting of both audible and visible alarms) should be established, with distinctive signals used for each type of emergency. Practice drills should occur periodically to ensure that employees are familiar with the alarms and know instinctively how to respond. The meanings of the various signals should be posted in all operational areas.
If no alarm system is provided in the facility, a means for notifying employees (e.g., a public address system) should be identified and practiced to ensure its adequacy during an emergency.