B&M Air Raid Sirens
| B&M Air Raid Sirens | |
[[File: |200px]]
| |
| Company | B & M Siren Manufacturing Co |
|---|---|
| Produced | 1930s(?) - 1960s(?) |
| Type | Electromechanical |
B&M is a manufacturer of vehicular and civil defense sirens, and is one of the longest running siren manufacturers, having been in business since 1913. While they currently only offer vehicular sirens, B&M used to produce large outdoor warning sirens during World War II and the Cold War. With other siren manufacturers having a much larger presence, B&M eventually discontinued their line of outdoor warning sirens due to declining sales. They are still around today restoring and building vehicular sirens.
B&M began making outdoor warning sirens sometime during the early 1930s, as patents for the 15-H-4 were filed in August of 1930. Advertisements also suggest they started building them in the 1930s. As World War II raged on and the Cold War loomed over the horizon, the demand for dual tone civil defense sirens was rising, to distinguish them from single tone fire sirens. B&M entered the market with a multitude of single and dual toned sirens, ranging from small single rotor sirens meant for tiny communities to large dual rotor sirens meant for big cities. These sirens had extremely efficient rotor designs, combining that with screaming high tones made for painfully loud sirens that can be heard for miles.
General Alarms
6GA
The 6GA is B&M's smallest electric siren, being only 1/2 horsepower with a 6 inch, 6 port rotor, shared with the 6FA friction siren. Despite being so tiny, the 6GA has proven to be extremely loud for its size, with a privately owned unit reaching 130 dBA from up close. The 6GA was also referred to as the 6-AR-1, as it was also sold under the air raid siren lineup as a siren for compact suburban areas. 6GAs were sold with bell shaped shrouds to cover the siren, though earlier models were non-shrouded horizontal units with large intake horns.
8GA
The 8GA is B&M's mid-size general alarm, equipped with an 8 inch, 8 port rotor, shared in design with the S8-B vehicular siren, apart from some minor changes to accommodate a standard shaft. They were sold with bell shaped shrouds to cover the siren. Few are known to exist in the wild, as the larger 10GA was a more popular choice.
10GA
The 10GA is B&M's largest general alarm siren, utilizing a 2.5 horsepower motor to turn a 10 inch, 8 port rotor. Especially popular in Texas and surrounding states, the 10GA is one of B&M's more common outdoor sirens. It was also referred to as the Model 10 and the Model 10-AR-2 under B&M's air raid siren lineup, being the second smallest siren of the pack. They were sold with either bell shaped shrouds, partially exposed shrouding (similar to a Sentry 5V), or weatherproof screened shrouds, similar to a Scream Master or Federal Signal Model 5. The 10GA also ended up being the base for B&M's S10-B siren, a vehicular siren built solely for collectors. There is a good few active 10GA sirens, as well as a handful in private ownership.
Air Raid Sirens
15-AR-5
The B&M 15-AR-5 is the smallest dual end AR series siren, presumably with two 15 inch rotors being driven by a 5 horsepower motor. None are known to exist. It was best suited for smaller cities, according to B&M.
20-AR-7
The 20-AR-7 is the mid-size dual end AR series siren, with two 20 inch rotors powered by a 7.5 horsepower motor. A good few units still remain today, albeit inactive or under private ownership. They came in 16/20 port standard, and no remaining examples have a different port ratio. The 16/20 port units are unique by using 8/10 port rotors inside of 16/20 port stators, with the rotor having half the port count of the stators. It is believed B&M did this to get more equal sound distribution out of the intakes and ports, leading to more uniform coverage. This would create two octave tones, making for a very odd sounding siren. The 20-AR-7 was best suited for large cities, according to B&M. B&M also offered a single rotor version of this siren, called the 20-AR. Four have been documented, and at least three exist today.
20-AR-10
The 20-AR-10 is B&M's largest AR series siren, with two 20 inch rotors, longer than what you see on a 20-AR-7, driven by a 10 horsepower motor. It was sold in 12/16 port with 6/8 port rotors, full 14/16 port, and possibly more. 5 examples remain today, one being only one 14 port rotor and the motor at B&M's facility, a display unit at an Orange County, CA fire station 46, Sierra Madre, CA's active unit, an inactive unit in Perris, CA, and another inactive unit in Carlisle, PA. The 20-AR-10 was best suited for widespread metropolitan areas, according to B&M.
H Series
15-H-2
The 15-H-2 is the smallest siren in the H Series lineup, being just 3 horsepower with two 15 inch rotors. The rotors are 6 port, and the stators are 12 port, making for an interesting octave tone despite being a single tone siren. Most likely because of it's price, the 15-H-2 was not a popular choice, being only $50 less than the 15-H-4 at the time. None are known to exist.
15-H-4
The 15-H-4 is the second siren in the H Series lineup, it has two 15 inch rotors driven by a 5 horsepower motor. The 15-H-4 is similar to the 15-H-2, just having longer rotors and a larger motor. Like the 15-H-2, the 15-H-4 is a 6/6 port siren with 12 port stators. All 15-H-4s known to exist have stator flanges for stator shrouds to be mounted, and one 15-H-4 in Kingman, AZ has horn extensions on the intakes. The 15-H-4 is the most common siren of the H Series, as it was the most reasonably priced, being much cheaper than the largest H Series siren. Three 15-H-4s are known to exist. B&M also made a vertical single rotor version of this siren, which was located in Bodega, CA. It has since been removed.
18-H-7
The 18-H-7 was the largest siren in the H series lineup, boasting two 18 inch rotors and a 10 horsepower motor. Not much is known about the 18-H-7, as it never sold well, likely due to being double the price of a 15-H-4. None have ever been documented, and none are known to exist today.
B&M continued making these civil defense sirens up until somewhere in the 1960's, as the last documented installation was in 1965. It's likely that they couldn't keep up with competition from other manufacturers such as Federal or B&N, as B&M had poor advertising and high prices for their sirens. B&M ultimately opted to switch back to purely making vehicular sirens, which they continue to do to this day, along with restoring any siren you present to them. Today, there are few B&M civil defense sirens left, as all but one have been taken out of service due to age, replacement, or towns simply no longer having a need for them. However, their vehicular sirens and general alarm sirens can be found in widespread use. Only a single active B&M air raid siren remains, a 20-AR-10 located in Sierra Madre, CA.