There is a bit of confusion regarding Denver Sirens and model identification. I have compiled several photos of each presently known model to date, starting smallest to largest. Each photo has an in-depth description, but I will include them below aswell. A huge thank you to Adam and Derek for some of these photos. You guys rock!!!
1. Early Type A. #1 of 2 remaining type A units. The early versions of these were 12/12 with a staggered port design, and the rotor was directly coupled to a 1 1/2 or 2hp 1750rpm motor. The first generation of this siren used the floating rotor design of the Duplex and Quadruplex, but used a transmission separate from the motor to drive the siren. None of these transmission driven units are known to exist. Located in Canova, South Dakota. Photo Credit: Derek Thompson, Feb 2023.
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2. Late Type A. This siren likely post dates 1920. This one appears to still be 12/12 but with a much simpler stator design, again direct coupled. #2 of 2 known units remaining. Located in Kanorado, Kansas. Photo Credit: Adam Pollak
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3. Type B. This siren consists of a standard 21" 20/20 port OR 21" 20 port single row head directly coupled to a 2hp 1750rpm motor. These were also available with a DC motor for motorship use. Located in Ferriday, Louisiana. Photo Credit: Adam Pollak
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4. Duplex. The most popular version, this model consisted of a 21" 20/20 port head with a floating rotor design. These sirens used a 3hp 1750rpm motor. These sirens were briefly avalible with a coding brake fixed between the motor and head, though no know surviving coded units exist. located in Lindsay, California. Photo Credit: Adam Pollak
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5. Quadruplex. This siren consists of TWO 21" 20/20 port heads and utilizes the same floating rotor design as the Duplex. This siren was avalible with a 3 or 5hp 1750rpm motor, though 5hp was highly recommend especially where multiple cycles of the siren would be used. Located in Grand Ledge, Michigan. Photo Credit: Me.
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6/7. The Center Drive Duplex. This siren consisted of two 6 port heads affixed on each end of a 5hp 3000rpm motor. This siren was designed and built at the very end of the company's lifespan, and the only known unit was installed at the now demolished Wheat Ridge Fire Department just outside Denver metro. Photo Credit: Colorado School of Mines Magazine 1928
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