Sentry Siren

"Premium Outdoor Warning Systems"

**Sentry Siren, Incorporated**, technically the successor to the Sterling Siren Fire Alarm Company, is a siren manufacturer that produces a wide range of omnidirectional sirens of many shapes, sizes, and sounds. Being little more than refreshed Sterling Model M sirens at the core, these sirens are known to be very reliable and low maintenance due to their omnidirectional design, although their designs are often inefficient.

## History

Sentry Siren began in 1972, founded by Scott and Bill Yarberry. The company was run out of Canon City, Colorado, and purchased the designs and rights to the Sterling Siren Fire Alarm Company's sirens, as Sterling had fallen on hard times and had gone out of business. Several sirens were carried over, including the Model M (which was renamed to the Model M-10), the Model 2V8, and the Model F-2. The sirens remained largely the same as their original Sterling counterparts around this time. Around 1973, Sentry would introduce their first custom siren, the 10V2T. The 10V2T was little more than a Model M that was placed into a vertical configuration with horns, but proved to be more popular. As a result, the Model M would see a redesign to match the 10V2T in the mid 1970s. While the company operated as Sentry Siren at this time, the tags on the sirens were marked as "The Sterling Siren Fire Alarm Corporation" instead of Sentry Siren until around 1976.

In 1980, seeing the success of the 10V2T, Sentry would release several more sirens, which included the 3V8, 5V, 10V, and 20V2T. The earliest known Sentry Siren models were much different from modern ones. Some notable differences include the bottom intake stand having eight legs instead of six, the cooling holes in the motor cover being placed differently, the horn extensions being larger and flat-edged, and more. These sirens would prove quite successful, and the lineup would be expanded further in the mid 1980s with the introduction of the 15V2T. Sentry's sirens proved to be reliable, and they often boasted about the superior performance of omnidirectional sirens over rotational sirens, due to their constant coverage.

Various other models would be introduced later on as the company grew, and today boasts a large number of siren models. Over the years, Sentry has branched out and made many different models. From battery-backed mechanicals to fully electronic, Sentry took a crack at just about everything. Sentry sirens are normally made out of steel, however stainless steel versions are also available upon request as they offer superior resistance to corrosion and weathering. Sentry's sirens are resold today by several different companies, including W.S. Darley & Co, and Edwards Signalling.

Sentry Siren continues to operate today, and their sirens are a common sight across North America. They have not been without issues, of course. Their only attempt at creating a rotational siren, the SS3 Defender, proved to be a flop, and their sales of their electronic sirens have been very poor. It can be expected that Sentry will continue to stick with omnidirectional mechanical sirens, where they truly excel. However, Sentry often arbitrarily rates the decibel ratings on their sirens, with several being overinflated. DC models are often marked as being up to 9 decibels louder than their AC counterparts, despite being the same siren mechanically. Other sirens have had their decibel ratings increased for no apparent reason despite no design changes. As such, the decibel ratings on Sentry's sirens should be taken with a grain of salt, especially given they are largely vertical Sterling sirens at their core. The rotor designs Sentry uses, which are designed for the horizontal Model M, shoot most of their output through the intakes, where it is wasted. In addition, the hooked, drag-heavy directional design of the rotors mean they perform much better when running *backwards,* which means single phase models can never reach their full potential. When running backwards, Sentry's sirens run at a higher speed and are much louder.

## Products

#### 3V8 (3V8-H, 3V8-H-B)

The **3V8** is a small omnidirectional siren produced by Sentry Siren, Inc. It is the smallest siren in Sentry's lineup, as well as the cheapest. It has been a mainstay in Sentry's catalogue since its introduction, and has seen use in many places for a wide variety of purposes. The 3V8 was introduced in 1980 as part of Sentry's 1980 lineup, which also included the 5V, 10V, and 20V2T, following the success of the earlier 10V2T. The 3V8 is the smallest of that lineup, and is intended for short range use, often by industrial sites or fire stations.

As early as 1999, a variant of the 3V8 was advertised with 8 horns attached to the stator ports instead of a skirt. This is branded as the **3V8-H**, and while it is slightly more expensive, the horns increase the siren's performance. With the exception of the horns, the 3V8-H is identical to the standard 3V8. These horns make the siren very similar in appearance to the 7V8, but shorter in height due to the 3V8's smaller rotor. In 2015, another variant of the 3V8 was introduced, named the **3V8-H-B**. The 3V8-H-B is the DC alternative to the 3V8, running on a 4HP 42VDC motor rather than a 5HP AC motor. This allows the siren to run on battery backup if AC power is lost, and is rated to run approximately 30 minutes after power is lost. The 3V8-H-B performs identically to a standard 3V8-H.

#### 7V8 (7V8-B)

The **7V8** is an omnidirectional siren produced by Sentry Siren, Inc. It is the midrange single rotor siren in Sentry's current lineup, replacing the 5V for this purpose. The 7V8 was introduced in the year 2000, alongside the 16V1T-B. The 7V8 was designed to replace the 5V, which lacked any sort of amplification for its sound, and became redundant. The 7V8 reaches the same sound output as the 5V, at 112 dB at 100ft, but the addition of horns allows the sound to be projected further.

In 2002, a DC-powered battery backup capable version of the 7V8 was released, designated the **7V8-B**. The 7V8-B uses an 8HP 72VDC motor instead of the 7.5HP AC motor of the standard 7V8, which allows the siren to run on battery backup if AC power is lost. The siren is rated to run approximately 30 minutes after AC power is lost before the batteries run out of power. The 7V8-B is otherwise entirely identical to the standard 7V8 in both appearance and performance.

#### 10V

The **10V** is an omnidirectional siren that is produced by Sentry Siren, Inc. It is the second largest of Sentry's single rotor sirens, as well as the most versatile. It is a mainstay of Sentry's lineup. The 10V was introduced in 1980 following the success of the earlier 10V2T, alongside the rest of Sentry's 1980 lineup which included the 3V8, 5V, and 20V2T. The 10V is the second largest single rotor siren produced by Sentry after the introduction of the 14V, and at the time of its release was the largest. The 10V performs at 115 dB at 100ft, according to Sentry.

#### 14V (14V-B)

The **14V** is an omnidirectional electromechanical siren that is produced by Sentry Siren, Inc. It is the largest and most powerful of Sentry's single rotor sirens, being little more than a 40V2T cut in half. It is intended for longer range use than its single rotor contemporaries. The 14V is one of Sentry's newest sirens, being introduced in 2015. The 14V is essentially a Sentry 40V2T that has been cut in half, using the same 10-port single tone rotor and stator as the lower half of a 40V2T. The 14V performs at 127 dB at 100ft, according to Sentry.

The 14V is also available in DC power, in the form of the **14V-B**. The 14V-B makes use of a DC motor with battery backup if AC power is lost. The siren is rated to run approximately 30 minutes before running out of power when running on its batteries. The 14V-B is otherwise identical to the standard 14V in both performance and design, with the only difference being the tag, nonlinear windup, and the addition of the battery enclosure next to the controls.

#### 10V1T

The **10V1T** is a vertical dual rotor omnidirectional siren produced by Sentry Siren, Inc. It was released in the early 2020s as the successor to the discontinued 10V2T. Intended to be a cheap dual rotor option for those on a budget, it is the smallest and cheapest of all of Sentry's dual rotor options. The 10V1T was released in September 2022, a few months after the 10V2T was discontinued in June of the same year. However, the siren did not appear on Sentry's website (along with the SV-8) until February 2023. The Sentry 10V1T performs identically to its predecessor, outputting 120 dB at 100ft in a 360 degree radius, at least according to Sentry's claims. This places it directly between Sentry's single rotor options such as the 7V8 and 10V and the larger dual rotor 15V2T or 16V1T-B in terms of performance and cost, making it a very cost effective siren.

#### 15V2T

The **15V2T** is a siren that is produced by Sentry Siren, Inc. Introduced as a stopgap between the 10V2T and 20V2T, it is a solid and popular choice for cities looking for a midrange dual rotor siren. The 15V2T was introduced in 1986 and has the distinction of being the first siren introduced by Sentry after their lineup in 1980. The 15V2T is nearly as loud as the 20V2T, while also not being quite as expensive, which makes it more appealing to customers. The 15V2T shares the same design as the 16V1T-B and 20V2T. The siren is able to reach 124 dB at 100ft as claimed by Sentry.

#### 16V1T-B

The **16V1T-B** is a DC-powered omnidirectional siren produced by Sentry Siren, Inc. The 16V1T-B is Sentry's most popular DC offering. The 16V1T-B was introduced in the year 2004, as Sentry's largest battery backup equipped siren. The 16V1T-B was the end result of an experiment by Sentry to create a DC-powered siren, in order to compete with the likes of Federal Signal's 2001 and ASC's Tempest series of sirens which were outselling Sentry's AC-only offerings. This began as the dual tone, dual rotor Sentry 15V2T-B in 2002, which was refined into the 16V1T-B.

The 16V1T-B shares the same design as the 15V2T and 20VXT. Due to running on DC power, the siren can run on battery backup, allowing it to run for approximately 30 minutes after AC power is lost. The siren is able to reach 129 dB at 100ft as claimed by Sentry, though this claim is questionable as it uses the same rotors as the 15V2T and 20V2T, which have a lower claimed decibel rating. Due to the nature of DC motors, the two motors do not run at the same speed, which causes a distinctive warbling sound as the two rotors clash.

#### 20V1T (20V2T)

The **20VXT** is a dual rotor mechanical siren that is produced by Sentry Siren, Inc. Essentially a higher horsepower variant of the 15V2T, the 20VXT is the second highest horsepower siren that Sentry currently offers, only beaten by the 40V2T. Following the success of the earlier 10V2T, the 20VXT was introduced in 1980 as the dual toned 20V2T, as part of Sentry's 1980 lineup, alongside the 3V8, 5V and 10V. The 20V2T was the loudest, largest, and most powerful offering that Sentry had upon its release. The 20VXT shares the same design as the 16V1T-B and 15V2T. The 20VXT is rated at 125 dB at 100ft by Sentry.

Early production 20V2T units used square horns, instead of round ones. These were the earliest 20VXT units produced, and were only made for a short time. Approximately 50 of these units were produced between 1980 and 1981, before it was decided that these were too difficult and expensive to produce. In 1981, the horns were changed to the round design used today. Very few of these units remain today.

#### 40V2T

The **40V2T** is a dual rotor electromechanical siren that is produced by Sentry Siren. It holds the title as the loudest siren produced by Sentry, as well as one of the loudest omnidirectional sirens ever produced, only beaten by the likes of the H.O.R. Super Sirex. The exact date of the 40V2T's introduction is unknown, though documentation exists as early as 1998 using the siren's current design. The 40V2T dethroned the 20VXT as Sentry's loudest siren upon its introduction, with its own unique design The 40V2T was originally rated by Sentry at 127dB at 100ft, but this was changed for no apparent reason to 131dB at 100ft despite no design changes. Thus, it is smart to take Sentry's decibel ratings with a grain of salt.

#### SV-8

The **SV-8** is an electronic siren produced by Sentry Siren, Inc, and is Sentry's second attempt to enter the electronic siren market. It is intended to replace the short-lived VR, which was Sentry's first electronic siren. The Sentry SV-8 was leaked by C and K Early Warning Systems in April 2022, with little information being released about it until the siren was released in February 2023, as Sentry's second attempt to produce an electronic siren. The SV-8 is a small electronic siren that is designed as a "Giant Voice" system, prioritizing voice clarity over raw sound output. The siren is rated by Sentry with an 0.85 - 0.95 Sound Transmission Index (STI) rating. The SV-8 is rated between 110-116 dB at 100ft, which is rather low for the wattage the siren uses. It is likely that this siren is intended for campus use rather than as a standard public warning siren, due to its prioritization of voice clarity over sound output and overall lack of raw performance.

F-2

The Model **F-2** (Factory siren, version 2) is a small industrial electric siren produced by Sentry Siren, Inc, and formerly the Sterling Siren Fire Alarm Company. Intended as a small industrial or rural fire siren, these sirens are the main competitor to the Federal Signal Model A and Model L. The F-2 began as the Sterling **Type F**, which was later re-released as the Model F-2 in 1972, featuring a simpler overall design. The siren's specifications remained the same at 117 dB at 10ft, using the same 8-port rotor, stator, and 1/5HP AC/DC universal motor.

## Discontinued Products

#### 5V

The **5V** is a small omnidirectional siren that was produced by Sentry Siren, Inc. It was one of Sentry's original sirens, and was produced for a period of 20 years before its discontinuation. The 5V was introduced in 1980 alongside Sentry's other 1980 lineup following the success of the earlier 10V2T, which included the 3V8, 10V, and 20V2T. The siren was able to reach 112 dB at 100ft according to Sentry. The 5V was eventually discontinued in the year 2000, when Sentry's lineup began to change. The 5V and the newly introduced 7V8 had very similar production costs and performance, which led to Sentry choosing to discontinue the 5V.

#### 10V2T

The **10V2T** is a dual rotor omnidirectional siren that was produced by Sentry Siren over a period of nearly 50 years. Being little more than a vertical 10HP Sterling Model M at its core with horns attached, the 10V2T was one of Sentry's earliest original siren designs and was an attempt to improve upon the Sterling Model M, which Sentry had purchased and redesigned in 1973 after Sterling Siren Fire Alarm Company went under. The 10V2T was introduced sometime between 1973 and 1976, when Sentry still operated under the Sterling Siren Fire Alarm Corporation name. The Model M (renamed to the Model M-10 by Sentry) would later be redesigned to share common parts with the 10V2T, and many other sirens would be later introduced after the 10V2T's success, such as the 3V8, 5V, 10V and 20V2T. The 10V2T was the lowest powered dual rotor siren in Sentry's lineup, though it has now been replaced by the 3V8-based 10V1T. The siren was able to reach 120 dB at 100ft as claimed by Sentry. The siren was available early on as a three-signal model with dampers, known as the **10V2T-3S**.

The 10V2T's sales dwindled over the years as its price and performance were lacking compared to Sentry's larger dual rotor sirens such as the 15V2T, 16V1T-B, and 20V2T, and the single phase offering was later discontinued, leaving it only available in three phase. This, along with increasing demand for sirens able to run on DC power, ultimately spelled the 10V2T's end. In June 2022, the 10V2T was officially discontinued, being replaced by the smaller 10V1T in September 2022 after a production life of 42 years. Though it is no longer officially produced, it is still available through special order or through Sentry's partners such as W.S. Darley & Co.

SS3 Defender

The **SS3 Defender** was a short lived rotational siren produced by Sentry Siren, Inc, as the company's first and only foray into producing rotational sirens. These sirens were plagued with issues and poor design, and as such are very rare to find in service, and Sentry no longer produces any rotational sirens. The SS3 was originally created around 2001, and was originally called the SS3. The siren reached 127 dB at 100ft, and came equipped with battery backup, allowing it to run up to 30 minutes after grid power is lost. Unfortunately, the Defender was plagued with issues from the beginning, and this led to the siren becoming quite unreliable. Due to its lack of popularity and its lackluster reliability compared to other DC sirens such as Federal Signal's 2001-130 and ASC's T-128, as well as Sentry's overall preference for omnidirectional sirens, Sentry ultimately opted to discontinue the Defender in 2011, after a 10 year production run. This would ultimately be the only rotational siren Sentry would make, as they decided that omnidirectional sirens were the superior option.

#### VR

The **VR** is an electronic siren that was produced for a short time by Sentry Siren, Inc. Being Sentry's very first attempt to enter the electronic siren market, the siren was only produced for a short time as Sentry failed to establish a foothold in the market. It was later succeeded by the SV-8. The VR was announced and introduced in 2018 on Sentry's website. The siren was advertised as a Giant Voice siren, being intended to function as a public address and notification system prioritizing voice clarity over raw sound output. These were advertised by Sentry as reaching up to 120 dB at 100ft while having an incredible speech transmission index (STI) rating of 0.91 out of 1.00. This meant that it would be able to be clearly heard and understood over a great distance, which was the siren's main selling point.

The VR was a complete failure for Sentry. Due to being a niche product that was poorly marketed, less than a dozen overall units are known to have been sold. In addition, Sentry's overall preference for mechanical sirens caused their attention to be focused away from the VR. This, combined with the siren's overall performance lacking compared to competing sirens such as the Modulator or WPS-2900, led to the siren's quiet discontinuation in 2020.