The Model 120 was a SoCal Edison Employee designed 120 dB siren built by John Glenn Powell, a now retired sound engineer at the San Onofre Nuclear Generating Station in San Clemente, California. There were 22 of these sirens produced with one being never installed which is now privately owned. 21 were installed in September 1982 along with 29 Federal Signal STL-10s. For around a decade, they were thought to be "Toshiba" sirens, because they were pneumatic and people just assumed they were made by Toshiba, who also made pneumatic sirens. The Model 120 is a Pneumatic siren, meaning it requires an external air source to produce sound. The sound is chopped by a rotor, which sits inside a hollow cylinder, or stator, which acts as a chamber to contain the air inside. 8 Small narrow slots on the stator allow the sound to come out. The sound is then projected by 8 large fiberglass horns. It consists of a belt driven Paxton blower, that uses a 5 Hp TEFC motor. The rotor is 9.75 inches in diameter that has 4 ports and including the stator it is in total 11.75 inches in diameter. The rotor is powered by a Gould 1 Hp TEFC motor that spins at 3450 RPM. Since its an octave interval siren it produces a frequency of 240 and 480 Hz, which allows their sound to penetrate objects really well, and carry very far. By the 1990s ,the Model 120s were starting to get corrosion on there rotor motors due to the motors not having a special type of paint that wont corrode like on commercially produced sirens ,And they were having constant malfunctions and failing to sound on routine maintenance and tests. In March 2006 ,the Model 120s, along with the STL-10s were all removed. Brand new Whelen 2810s and 2806s were installed in their places. These new electronic sirens have battery backup, and are much more efficient. A few of the STL-10s went to communities in Oregon, and the Model 120s were scrapped according to a former SONGS employee that helped with the Whelen upgrade. The only one that is remaining is in the possession of Duderocks5539, and Edaan Friedman.
Siren patent: https://patents.google.com/patent/US4649853