Screamer

ACA Screamer
An ACA Screamer S-10 in Enoree, SC, photographed by Christopher Jancse.
Company	Alerting Communicators of America American Signal Corporation
Produced	1967-2004
Type	Omnidirectional Electromechanical
Sound output	102-112 dB @ 100 ft
Frequency	60 Hz
Horsepower	2-10 hp
Voltage	208-230/460 V 1 or 3 ph
Preceded by	BNCO Model 110
Succeeded by	ASC Tempest

The Screamer is a series of small omnidirectional sirens that was produced by Alerting Communicators of America (ACA) and later the American Signal Corporation (ASC), and is the smallest of ACA's omnidirectional sirens (not including the short-lived Sentry 95), with the larger Banshee and Cyclone sirens being sold alongside them. Later produced by ASC under the OM Series, the Screamer would be replaced by the Tempest omnidirectional sirens in 2004. It was ACA's main competition towards Federal's Model 2 and Model 5.

History

An early Screamer pictured in a ACA catalogue.

A Screamer Model 108, located in Hysham, MT. Image credit to Montana Siren & Train Production.

The Screamer first appeared in ACA's catalog in 1968, a year after Jim Biersach reformed Biersach & Niedermeyer's siren division into ACA. These early Screamers had a more unified design, with the same shroud shape being used for every model, lacking a mounting bracket on the motor, and the model names also differed from the later Screamers. 3 known models were produced, these being the Model 100, Model 105, and Model 108. In 1973, the Screamer sirens were redesigned into 5 (later 4) models, the Model S-2, Model S-3, Model S-5, Model S-7.5, and Model S-10. Each siren would have its bottom motor mount replaced by an L-shaped bracket, which the motor would be attached to from the side. Its design would remain unchanged throughout the series' production run, even as ACA renamed the series in 1992 as BNCO was facing severe financial troubles. During this time, the Screamers were sold as the Model SC-2, Model SC-5, and Model SC-7.5, and the Banshee and Cyclone would be sold as the Model SC-15 and Model SC-50 respectively, being incorporated into the Screamer series. The Screamer would be sold under these names until 1994 when BNCO faced bankruptcy and ACA was sold off and reformed into American Signal Corporation by HÖRMANN America.

Most of the Screamer line would be carried over into ASC and continue production, with the Model S-2, Model S-5, and Model S-7.5 all being produced by ASC. These are completely identical to their ACA versions, with the only difference being the paint being gray instead of yellow, and the addition of ASC decals. The Model S-10 was not carried over, as the need for dual-tone sirens had passed, and as such production of the Model S-10 would end in 1994. The Screamers would be renamed to the Model OM-102, Model OM-109, and Model OM-112, with the Banshee becoming the Model OM-117. The Cyclone would be renamed to the Model C-125.

The Screamers would be sold under ASC until 2004, when the series was finally retired in favor of ASC's newer Tempest series of sirens, the Model T-112 and Model T-121, which were both louder, and had DC motors allowing for battery backup. Many Screamers still operate to this day as both their original and ASC variants, as their simple design makes them reliable, and low maintenance. However, they never sold as well as Federal's Model series that they were competing with. What the Screamers lacked in power, however, was made up for in punch. It can be expected that many Screamers will continue to warn the public for many years to come.

An early 8-port Screamer, located in Brownsville, KY.

Design

The Screamer is a very simple siren in design, with a motor of variable horsepower attached to a mounting bracket, that drives the rotor. Screamers come with a fiberglass weatherproof shroud that protects the siren from the elements, with the shape differing depending on the model. The siren intakes from above with a rotor-over-motor configuration, something that differs it from more powerful ACA models. The rain shield and skirt project sound from the intake, while the skirt projects the output from the rotor evenly. Several eyebolts are placed on the rain shield in order to facilitate easier mounting. This simple construction makes them relatively maintenance-free. Most Screamer models lack a top ring on the stator, with the exception of the S-10. 6 different models of Screamer were known to be produced:

Model S-2

A Screamer Model S-2 in Meeker, OH, photographed by Fumikiri06.

The Model S-2 is the smallest of the Screamer sirens, as well as the cheapest. Originally introduced into ACA's lineup as the Model 100, it originally used the same shroud style as the other early Screamers. It would later be redesigned with a motor mounting bracket, and a different shroud, and would be renamed to the Model S-2. The Model S-2 uses a 2 hp AC motor, driving a 9-port single-tone rotor which allows the siren to reach 102 dB at 100 ft. These came in both single and 3 ph AC. A 2.5 hp variant of this siren was also produced, tagged as the Model S-2.5.

The S-2 is very often confused with the S-7.5 due to their similar appearance. The S-2 can be told apart from the S-7.5 by the very small lip under the stator, which extends much further out on the S-7.5. The S-2 also uses a thin rounded capacitor housing on 1 ph units, while 1 ph S-7.5 models use a large square capacitor housing. The S-7.5 is also physically larger than the S-2.

These are intended for use at fire stations and other areas where small coverage is needed, similar to Federal Signal's Model 2. 1 ph S-2s make use of a start capacitor, which creates the necessary phase shift in the start winding to get the motor rotating. The drag caused by the centrifugal switch that disconnects the start winding once the motor is up to speed causes a sharp and sudden drop in pitch during winddown, similar to Sentry Siren's 1 ph sirens. The S-2 would continue to be sold after ACA's reformation into ASC as the ASC OM-102 until 2004.

Model S-3

A Screamer Model S-3, located in Walters, MN.

The Model S-3 was a very short-lived option that is essentially just a Screamer S-2 with dual run capacitors and a slightly more powerful 3 hp electric motor. The only visual difference between the S-2 and the S-3 is the larger, squared capacitor housing on the side of the motor. Despite the rotor and stator being identical, ACA rated this model 103 dB at 100 feet, despite the increase in horsepower not translating to increased performance. It's likely the Model S-3 met a similar fate to Federal Signal's C1 1/2 Model 3, where it was only marginally better than the 2 hp model and was seen as redundant. Due to its redundancy, the siren was discontinued early on. At least one S-3 is known to exist today, located in Walters, MN.

A Screamer Model S-5 in Weathersfield Township, OH, photographed by Fumikiri06.

Model S-5

The Model S-5 is the midrange option in the Screamer line and can be differentiated from the Model S-2 and the Model S-7.5 by its shroud. Rather than having the chopper stick out from underneath the shroud, the shroud now completely covers the height of the chopper, which makes it visually distinct. This is due to the rotor and stator being shorter in height than other models. The rotor diameter is the same as the Screamer S7.5, but only half the height. People often mistake the Model S-2 and Model S-7.5 for the Model S-5, due to not knowing the differences. The Model S-5 came exclusively in a 9-port single tone, and makes use of a 5 hp 1 or 3 ph AC motor, which increases its sound output to 105 dB at 100 ft. The siren was primarily intended to compete with Federal's General Alarm Sirens. The Model S-5 would be later sold as the Model OM-109 after ACA was reformed into ASC and would be sold until 2004 when it was discontinued.

A Screamer Model S-7.5 in Lomira, WI, photographed by Tom Diener.

Model S-7.5

The Model S-7.5 is the second most powerful Screamer, and a step up from the S-5. The Model S-7.5 was available exclusively in a 9-port single tone, reaching 108 dB at 100 ft. It is driven by a 7.5 hp AC electric motor, produced by Baldor or Doerr depending on the age of the siren.

The S-7.5 uses the same width rotor and stator as the S-5, but both are doubled in height. This gives it an appearance very similar to both the S-2 and the S-5. The S-7.5 is often confused with the S-2, but can be told apart by the much wider lip under the stator (identical to the S-5's) and its overall larger appearance to the S-2. 1 ph S-7.5s also use a much larger square capacitor housing instead of the S-2's thin, rounded capacitor housing.

These were also sold by ASC as the Model OM-112 after ACA was reformed into ASC until 2004, when it would be discontinued. The rotor from this siren would also be used in the ACA PN-20 and later the ASC RM-130.

The rotor and stator of a 9/12-port Screamer S-10.

Model S-10

A Screamer Model S-10, located in Toledo, OH. Image by Calvin Mayer.

The Model S-10 is the largest of the Screamer sirens. They are very similar in design to the Screamer S-5, with both making use of a flatter shroud, but rather than using the 9-port single tone rotor of the other Screamers, the Model S-10 came in 9/12-port dual tone, and 8-port single tone. Early units were also available in 10/12-port dual tone, using the rotor and stator from the BNCO Mobil Directo. The S-10 uses a 10 hp exclusively 3 ph AC motor and was originally released as the Screamer 100, before being redesigned and renamed to the S-10 in 1973. These are the only Screamers that came in dual tone. The siren reached 112 dB at 100 ft, making it the loudest of all Screamers. Unlike the rest of the series, the Model S-10 was not carried over after ACA was reformed into ASC, and as such it was discontinued in 1994. Due to dual tone sirens falling out of favour by the 1990s, as well as being nearly identical to the Banshee 115, the Screamer S-10 had little reason to continue being made.

A later model 3-signal Screamer Model 105, which had been removed from Exeter Park, PA around 2007. The siren later vanished. The picture has been rotated for a better view.

Screamer 105

The sole surviving Screamer Model 105, located in a museum in Oak Harbor, WA. It is an early 2-signal model which lacks the lower rotor and stator.

The Screamer 105 was a short-lived model of Screamer that was introduced alongside the others in 1968. The Screamer 105 is a unique siren, differing in design from the rest of the series. It is a small 8-port omnidirectional siren with a motor-over-rotor configuration, with a 5 hp Doerr AC motor driving the small rotor. The motor has a built-in 2-stage air compressor which works similarly to that of a Chrysler to feed air into the rotor, which is meant to improve the siren's performance. The siren's overall design resembles that of a CLM Type 92763CP, with a large mesh screen protecting the siren's motor and rotor.

The siren was offered in both 2 and 3-signal models, with the 3-signal model having an extended intake with damper to allow it to create pulse signals. At some point in the siren's lifetime, the siren was redesigned with a larger 9-port rotor and stator placed underneath the siren, which was similar to other single-tone Screamers. The upper rotor was kept, and this was likely a last-ditch attempt to get more performance out of the siren as well as making the siren 8/9-port dual tone. The Screamer 105 was ultimately a failure, selling few units and being discontinued in 1973 when the Screamer line was finalized in design. Today, only a single example remains in existence, an early 2-signal model on display at the Pacific Northwest Naval Air Museum in Oak Harbor, WA.