CLM Sirens

**Decibel rating (100ft)** | 130 dB (Type 927xxDP)
105 dB (Type 92763CP)
 **Type of siren** | Rotational Electromechanical
Omnidirectional Electromechanical

**Canadian Line Materials** (**CLM**) was a steel manufacturing company based in Scarborough, Ontario. Founded in the early 1950s as a division of McGraw-Edison, they produced a wide variety electrical equipment before being contracted by the Canadian government to manufacture air raid sirens for civil defense. Once common across Canada, these sirens are now very rare, though they remain a staple of the nation's Cold War history.

## History

CLM started off as a small steelwork company in Scarborough, Ontario, part of the larger McGraw-Edison company, producing electrical equipment such as lightning arresters. Early on into the company's history, CLM was commissioned by the Canadian government to create air raid sirens for civil defense. CLM made several different sirens, both rotational and omnidirectional. All CLMs were designed with the harsh Canadian winter in mind, and as such, measures were taken to protect them from the elements. All CLM siren controllers were equipped with a special mode that would operate the siren's rotors at all times at a very low speed, between 60-75RPM, in order to prevent ice from building up and potentially jamming the rotors and burning up the motor. All CLM sirens use directional rotors, which allows the siren increased performance as long as the rotors are spinning in the right direction. Reverse wired three phase units have slightly worse performance than a correctly wired unit.

CLMs were installed across Canada during the 1950s and 1960s alongside electric B&N Mobil Directo sirens, especially in larger cities like Toronto and Ottawa, ON. After the Cold War, all of these sirens were decommissioned as there was no more use for them, and it was found that many of these sirens were prone to malfunctions with the controllers as they aged. As most of Canada doesn't get severe weather like tornadoes often enough to warrant them, sirens do not have much of a purpose there. A few of them still sit on top of poles and rooftops, rotting away and abandoned, while others have found their homes in museums and private collections. A few CLMs have been refurbished and put back into service as fire sirens. These include a 20/24 port Type 5223 unit in Alvinston, ON, Single phase Type 5261 CLM fire siren variants in Port Lambton, ON and Qualicum Beach, BC, and a single active rotational CLM used as a fire siren in Alliance, AB.

## Products

### Stationary Electric Sirens

#### Rotational

##### Type 927xxDP

    The CLM Type 927xxDP is a unique dual rotor rotating electromechanical siren, and is largely a CLM Type 5263 (mentioned below) siren with two horns and a rotator mechanism attached. It came exclusively in 10/12 port dual tone. It appears that the siren was originally intended to be 12 port single tone, with the 12 port side having a large rounded horn, however the Canadian government dictated it to be dual tone, so the 10 port side with a much smaller rectangular horn was added on as an afterthought. The 10 port side has only 4 ports on the stator, with a 10 port rotor, and its intake has a diamond shaped cover. Because of this, the 12 port side is significantly more audible than the 10 port side at a distance. However, the 10-port side is dominant near the siren, as the rear intake forces the sound downwards while the front horn projects the sound far away. The siren is driven by a bare dual sided 5HP AC motor, which is attached to the rotator shaft by two tall brackets and a plate. The Type 927xxDP was claimed to be around 130 dB at 100ft, although this claim is debatable and unconfirmed.

The CLM Rotational siren came in two models, the Type 92730DP (3PH AC 220V) and the Type 92729DP (3PH AC 550V). These were not available in single phase.

    The rotator is powered by a separate 1/3HP motor, with a vertical belt driven pulley attaching the motor to a gearbox below it, which then drives a chain-driven pulley rotating the siren at approximately 12RPM, far faster than most rotating sirens. It is only beaten by the Swedish Electric Co. rotational sirens in default rotation speed, and is the fastest rotating siren with gear reduction. This causes the siren's sound to waver significantly as it rotates. The motor starter in the CLM's controller is configured by default to control both motors at once, meaning that it stops rotating immediately when the rotor shuts off. However, the rotator can be used independently of the rotor when directly using the controller. The rotator is housed inside of a tall rectangular housing, with two removable panels allowing access to the internals. The siren's collector rings and fuses are also located inside the housing. There are two handles which allow easy removal of the side panels, and four eyebolts are attached to each top corner of the siren to allow easy mounting with a crane.

#### Omnidirectional

CLM also produced a multitude of omnidirectional sirens, including:

##### Type 92763CP

    This is a 3HP vertical omnidirectional siren which came exclusively in 10/12 port dual tone. They were available only in 220V single phase AC. These were a vertical option that were designed to be used as part of a wider system, often supplementing Type 927xxDP rotational sirens by filling coverage gaps, although they were also occasionally used in their own systems. These bear a slight resemblance to the Federal SD-10, using two curved surfaces to help project the sound outwards, rather than using horns. Unlike CLM's other sirens, this used a single 10/12 port rotor and stator rather than two split rotors. The siren has two intakes, with the top intake having a very large rainshield above it which also acts as the upper projector, while a second intake is located below the rotor. A large skirt is included under the stator, which serves to complete the two projector surfaces. The 12-port side is fed by the top intake while the 10-port side is fed by the lower intake. The siren uses a rotor-over-motor configuration, with the siren's bare motor being located underneath the siren, unprotected from the elements. A mesh screen is included on both intakes to protect the rotor. CLM rated this siren at 105 dB at 100ft. These sirens are very rare, with few in service or private possession. One of these sirens is in active use as a fire siren, in Perth-Andover, NB.

##### Type 5263

This is essentially a Canadian clone of the British Carter siren, being a near duplicate of a standard Carter but running at 60hz power rather than 50hz. This causes them to be higher pitch than Carter sirens. These ran on 5HP dual-sided AC motors, with one 10-port rotor and stator and one 12-port rotor and stator on each side, resulting in a 10/12-port siren. These were available in 220V single or three phase, though three phase models are significantly more common. These are also sometimes known as "Mailbox" sirens, and these are quite often found inside specialized boxes to protect them from the elements. These use the same rotors as the Type 927xxCP rotational sirens. These sirens are some of the least common surviving CLM models, with few remaining in service or private possession.

##### Type 5261

    This is another Carter-like siren, but with a few differences. This siren was meant for use at fire stations and other areas where three-phase power may be too expensive or impractical to use, and uses a 3HP 220V brushed single phase motor. Like CLM's other sirens, this siren came in 10/12 port dual tone, and has significantly thinner rotors to reduce the load on the motor. The siren is not centered on its base, with the motor extending outwards more on one side than the other, and it has a hole on the side of the motor to access the brushes. Like most single phase sirens with brushed motors, these sometimes run into reliability issues due to the brushes wearing out and can struggle to reach full pitch. These are the most common CLMs found in the wild, with some still in service as fire sirens.

##### Type 5223

This is a unique 20/24 port dual tone siren, which featured significantly larger 26-inch rotors than CLM's other models. These are unique in that the two-pole motors ran at half the speed of most siren motors, at only 1625RPM instead of ~3500RPM. Because it has twice the ports of a regular 10/12 siren while running at half the motor speed, it sounds nearly identical to a 10/12 port siren. These likely weren't too popular, since they offered no advantages over a standard CLM Carter and were much heavier. These sirens tend to have longer winddowns due to the size of their rotors. These were available in either 220V or 550V three-phase, with no single phase option. These sirens are often found on display or in private possession, and very few are known to currently be in service. However, Alvinston, Ontario's fire department plans to put their Type 5223 into service as a fire siren.

## References

1. ↑ Video of the Alliance, AB CLM Rotational