Hazardous materials are chemicals, hydrocarbons, or other man-made compounds that have accidentally been released from their containers. See Hazardous Materials for further information. The function of both is the same. When smoke or smoke particulates are detected, an alarm will sound. This alarm is usually a high-pitched steady tone and the detector may have flashing or strobe lights.
Smoke detectors are either hard-wired or battery operated or a combination of the two.
When a smoke detector starts giving a low occasional chirping sound, this indicates that your battery is going dead. If you buy a smoke detector, read the manufacturers' direction completely. In most cases you are given instructions at the time of the evacuation orders. It is extremely important that you follow directions at the time you are told to evacuate. You should be told where to go and how to get there.