![]() Then in the 70s, they switched to a duotone airhorn, which was itself overtaken in the 80s by an electronic wail. The first emergency vehicles relied on a bell. Fire sirens are often tested once a day at noon and are also called "noon sirens" or "noon whistles". Civil defense sirens also used as fire sirens often can produce an alternating "hi-lo" signal (similar to emergency vehicles in many European countries) as the fire signal, or attack (slow wail), typically 3x, as to not confuse the public with the standard civil defense signals of alert (steady tone) and fast wail (fast wavering tone). Although there is no standard signaling of fire sirens, some utilize codes to inform firefighters of the location of the fire. Some newer sirens are electronically driven speakers.įire sirens are often called "fire whistles", "fire alarms", or "fire horns". Most fire sirens are single tone and mechanically driven by electric motors with a rotor attached to the shaft. Fire sirens can also be mounted on or near government buildings, on tall structures such as water towers, as well as in systems where several sirens are distributed around a town for better sound coverage. Most fire sirens are either mounted on the roof of a fire station or on a pole next to the fire station. Many fire sirens (used for summoning volunteer firefighters) serve double duty as tornado or civil defense sirens, alerting an entire community of impending danger. There are two general types: mechanical and electronic. ![]() Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines. ![]() Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. They are tested once a year, on the first Wednesday in February. There are 8,200 alarm sirens for civil protection throughout Switzerland. ![]() Electronic Sirens Pavian by Telegrafia A Whelen WPS electronic siren imported to Saudi Arabia by HSS Engineering for use as a Civil Defense siren. ![]()
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