Have you ever wondered how Hand Cranked Sirens work?

Have you ever wondered how Hand Cranked Sirens work?

Hand cranked sirens are a simple warning signal, perfect for environments and applications where electricity is not available. They are also the perfect solution to use as a back-up alarm when there is a power failure.
So, how simple is simple?! Easy! You hold the siren in one hand whilst using the other hand to turn the crank handle! No power supply is needed, and they are maintenance free!
They work by manually turning or cranking the handle a few times to produce a sound, slowly getting louder with every turn. Inside the siren there is a motor that drives the shaft with an attached rotor to both ends. The rotor surround stator has a number of slots that are almost rectangle in shape. Each of the blades draws and forces air through the slots inside the stator whilst the plates at the end of each of the blades stop or interrupt the flow. As a result, it creates rarefied and alternating compressed air pressure that products a sound.
We offer a range of hand cranked sirens:

HDS-1 Siren.
This is a hand-held device, cast aluminium material. The siren has an additional finger trigger to adjust sound as needed:
https://beaconlamps.com/products/audible-warning-signals/hand-cranked-sirens/hds-1/

HDS-2 Siren.
This is a tripod design device, cast aluminium material. The siren sits on the tripod whilst the drive handle is being cranked:
https://beaconlamps.com/products/audible-warning-signals/hand-cranked-sirens/hds-2/

Contact us for more information! 01283 550850 / mail@beaconlamps.com

The different types of Audible Warning Signals

The different types of Audible Warning Signals

When choosing an audible warning signal for industrial purposes, there are some aspects you need to consider before choosing the correct signal.

Firstly, you need to consider what type of audible warning signal you require from a range of:

Electronic Sounders

In today’s world of technology, an electronic sounder is the most versatile product to use as this can be programmed to offer multiple tones and can be volume adjustable, making them suitable for almost every requirement. – – Sirens.

Sirens are a motor-powered device producing a unique sound due to its internal impeller.

Bells

Bells are suitable for daily signalling use that produces medium db output. Most commonly found in schools and workplaces to alert for lunch breaks.

Air Horns

Air horns are a good option for industrial & marine areas and hazardous areas. It is a non-electrical device with a high db output and low frequency, making it ideal for noisy environments.

Buzzers

This is an electro-mechanical type of warning signal in a robust housing. They produce medium-high db output with a low sound frequency

Hooters

Hooters are a motor-powered warning device with a horn. It has a high db output with low sound frequency, ideal for indoor and outdoor use.

You now need to take into consideration the sound level and frequency rating of your chosen alarm – this needs to be heard instantly and distinctly above any other noise in the area.

Next you need to consider the power consumption, electrical supply and IP rating of your chosen alarm and check with your engineer this will be suitable for your application.

Lastly you need to ensure you choose a quality product that will stand the test of time so to speak. By purchasing a quality product to begin with, it will save you time and money in the long run in maintenance, especially if the alarm is located in a hard to reach area.

Audible Warning Signals

Audible Warning Signals

We use audible warning signals every day in our daily lives albeit it in different forms – whether it be your alarm clock waking you in the morning, a bell to signal lunch break or a louder noise to signal an emergency situation.

When used for industrial purposes, there are some aspects you need to consider before choosing the correct signal.

Firstly you need to consider what type of audible warning signal you require from a range of:

Air horns

Air horns are a good option for industrial & marine areas and hazardous areas. It is a non-electrical device with a high db output and low frequency making it ideal for noisy environments.

Electronic sounders

In today’s world of technology, an electronic sounder is the most versatile product to use as this can be programmed to offer multiple tones and db selections for almost every requirement.

Bells

Bells are suitable for daily signalling use that produces medium db output. Most commonly found in schools and workplaces to alert for lunch breaks.

Hooters

Hooters are a motor-powered warning device with a horn. It has a high db output with low sound frequency, ideal for indoor and outdoor use.

Buzzers

This is an electro-mechanical type of warning signal in a robust housing. They produce medium-high db output with a low sound frequency.

Sirens

Sirens are a motor-powered device producing a unique sound due to its internal impeller.


You now need to take into consideration the sound level and frequency rating of your chosen alarm – this needs to be heard instantly and distinctly above any other noise in the area, for example above machinery noise.

Next you need to consider the power consumption, electrical supply and IP rating of your chosen alarm and check with your engineer this will be suitable for your application.

Lastly you need to ensure you choose a quality product that will stand the test of time so to speak. By purchasing a quality product to begin with, it will save you time and money in the long run in maintenance, especially if the alarm is located in a hard to reach area.

See more on our range of audible warning signals: https://beaconlamps.com/products/#132

Audible Warning Signals

Sounders & Sirens

Sounders and sirens are used to attract attention particularly when an immediate response is required. To alert a person, it is recommended that a sounder or siren reaches between 5 and 15 dB(A) louder than the background noise of the given area.

There are several things to consider before selecting a sounder or a siren:

  • The sound pressure level achieved (quoted as decibel or dB(A).
  • The distance it must be audible over.
  • The frequency quoted in Hz.
  • The background noise of the area it will be installed in.
  • The duration of each use – duty cycle or prolonged use.
  • Ensuring the tone of the sounder or siren does not sound similar to any machinery etc in the same area.

To enable an easy comparison, the dB(A) stated for a sounder or siren is usually measured at a distance of 1m. When the distance is doubled the dB(A) is to drop by 6. This is why it is important to know not only the dB(A) of the sounder or siren is capable of, but also the distance away from the intended area it will be placed.

Using our IAS-E sounder and MDS-2 siren as an example of this:

DistanceIAS-E SounderMDS-2 Siren
 
1m110 dB(A)114 dB(A)
2m104 dB(A)108 dB(A)
4m98 dB(A)102 dB(A)
16m86 dB(A)90 dB(A)
128m68 dB(A)72 dB(A)
256m62 dB(A)66 dB(A)
512m56 dB(A)60 dB(A)
1024mx54 dB(A)

As you can see from the above, when choosing a sounder or siren, louder is always better. It is worth noting however that studies have found that is it possible to distinguish a sound that is up to 10 dB below ambient as long as there is sufficient frequency differential.

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Motor Driven Sirens

Motor Driven Sirens

Motor driven sirens are a typical style of an audible signal. They work by the motor driving a bladed impeller, pulling in air and pushing it back out through vents to produce a whirring sound – similar to an air raid siren. These units are commonly used in remote areas where a distinct noise it required to warn of an emergency.

Motor driven sirens usually have a duty cycle; for example 5 mins on and 10 mins off, so be sure to check this suits your application before using one.

As with all audible signals, these sirens have many pro’s and con’s:

Pro’s

 – Tend to be lower priced due to a simpler design.

– Lower frequency which travels better through and around object.

– Good to use in remote areas or in an area where electronic tones are used for fire alarms, and a siren is required to warn of something else.

Con’s

– Is only single tone and has no volume control.

–  High current draw and low efficiency.

– Lower IP rating due to the exposed blades which can get blocked with dust and debris.

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