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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Technical Advice => Topic started by: Wiz on February 24, 2009, 12:07:44 PM
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The disabled refuge communication system installed has in-built noise cancelling circuitry to try and ensure the clearest speech communication possible.
However this noise cancelling circuitry cannot cope with the background noise of the fire alarm sounders thereby making the speech unintelligible!
Anyone had anything similar?
Could it be argued that the recommended fire alarm sound level could be reduced in the disabled refuge areas, as a BS variation, to allow speech to be understood?
Could it be argued that the disabled refuge communication system should only be used after the fire aalarm sounders have been silenced anyway?
Whadyafink?
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I've had a lot of new builds over the last 12 months where they have accepted that a sounder is not provided in this area, but just a beacon for visual indication. Therefore overcoming the problem
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The disabled refuge communication system installed has in-built noise cancelling circuitry to try and ensure the clearest speech communication possible.
However this noise cancelling circuitry cannot cope with the background noise of the fire alarm sounders thereby making the speech unintelligible!
Anyone had anything similar?
Could it be argued that the recommended fire alarm sound level could be reduced in the disabled refuge areas, as a BS variation, to allow speech to be understood?
Could it be argued that the disabled refuge communication system should only be used after the fire aalarm sounders have been silenced anyway?
Whadyafink?
I'm guessing that if the BS has a reduction for areas where people summon for the fire brigade over the phone then the DDA would find a way that the same right should be afforded to a wheel chair person summoning for help over a refuge system.
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What about alternation between 'the disabled refuge communication system' and 'alarm sounders', if the disabled area is not separate, an external relays may have to be used to switch OFF the sounders for the short periods while the speakers are ON and vise versa..., but I don’t know if this is acceptable by BS…
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There is a particular manufacturer I know of that has a volt free output in each of the remote call stations. This is operated when the remote call station is activated by the user. Not sure if this is common across other manufacturers?
But on an addressable system you could feed this into an input module to isolate a particular sounder. Although isolating a sounder when the system is already in alarm may prove difficult. Actually this isnt something I have personally tried. Is this even possible?
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Technically yes; it is possible but, I am not sure if BS accept stopping the sounders for some reasons like this.. or other reasons
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I would not have a problem with reduced sounder levels in staircases as a sensible variation in the circumstances described.
You can never write general rules on when the fire alarm may be silenced. It can be silenced when it has served its purpose- and all persons are safely accounted for. For example in a care home you may write special rules allowing the alarm to be silenced but not reset when all staff have responded.
You could also argue that as the emergency communication device is usually next to the fire alarm panel, the responsible person could temporarily silence the alarm to use the comms device if he thought it would help, but this may confuse persons still evacuating and some may turn round and re-enter the building.
The best solution is to ensure that persons in refuges receive an early visit and support of a fiire warden and offered whatever assistance is needed. But its a very good point you raise Dr Wiz and we must never forget what it must feel like to be stuck by yourself in a wheelchair in the upper floors of a building on fire, and everyoune else walking out.
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I think going along the lines of relays on refuge systems and more I/O units and cause and effect programming etc in order to silence one or two sounders in the locality of the refuge point when it's in use is just over complicating the system.
I'd go with the reduction of alarm levels in the area....
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I would go with a beacon in this area as the sounders have already acheived there goal and the person has evacuated to the refuge.
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What about beacons and speakers throughout, and no sounders at all
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Having a voice alarm or even voice enhanced sounders I think would prove a costly increase, as 99% of new builds have the requirement for disabled refuge stations now.
I think the idea of beacons only at the refuge point is a good compromise, giving the user a good viable system
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Thanks for all the comments and opinions.
For everybody's information, there is no alarm sounder in the disabled refuge area, however the sound level is still at 63db in this area, and this is enough to affect the quality of the disabled access refuge communication system in use. The alarm sound level has to be reduced to 50 db before the interference is reduced sufficiently to allow the speech communication to work satisfactorily.
I feel that the technical solutions to provide automatic or manual alarm sound level reduction only when the speech communication system is used are potentially too expensive or add possible confusion to how the system would work.
In the circumstances we will seek a variation to reduce the alarm sound levels in this area but also provide an alarm visual warning beacon. We will also talk with the communication system manufacturer further and maybe they can adapt the design of their equipment to reduce this problem in future installations.
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Dr Wiz
In the situation you describe the noise level both in the refuge and at the control panel may make it difficult to communicate from either end. Alternatively the intercom system may amplify the alarm sound more than the voice frequencies and add to the problem.
There are frequency specific attenuators available exactly for this purpose. When I worked on a fire control room project we had a common problem that the 999 operators could not hear the message and also suffered discomfort because of the sound of the alarm feeding into their headsets, the filters were very effective at controlling this.
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Good call Prof. That is exactly the type of thing that the manufacturers will be asked to look at. The problem is where the alarm sound uses lots of frequencies and so any masking circuitry will then mask those frequencies of normal speech as well.
As an alternative I am considering a morse code disabled refuge communication system using large filament lamps as the indicators. Obviously, all disabled users, management staff and attending fire service officers will have to be trained in Morse code, but we see this as a small price to pay for the benefits provided ;)
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-/..../.-/-/...// .- // --./---/---/-..// ../-.././.-//
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As an alternative I am considering a morse code disabled refuge communication system using large filament lamps as the indicators. Obviously, all disabled users, management staff and attending fire service officers will have to be trained in Morse code, but we see this as a small price to pay for the benefits provided ;)
Can you elaborate a little more on your morse code consideration Wiz, especially the training bit?
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I cannot understand why you are so stuck in the past Dr Wiz.
Filament lamps for use with morse code is really old technology and there are much better modern solutions to this outdated technology.
Have you thought of using LEDs instead of filament bulbs?
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As an alternative I am considering a morse code disabled refuge communication system using large filament lamps as the indicators. Obviously, all disabled users, management staff and attending fire service officers will have to be trained in Morse code, but we see this as a small price to pay for the benefits provided ;)
Can you elaborate a little more on your morse code consideration Wiz, especially the training bit?
There will be a number of training schemes, each suited to the type of user.
The disabled users will be taught to use the transmit key with various parts of their body and also how to hook up to the various type of receive stimulus (other than the standard visual version) which includes, amongst others, electric shocks at high voltage but low current.
The staff, if local authority employed, will receive their trainining at our purpose-built facility in Hawaii. The two-week long course will also include jobsworth training as related to morse code applications.
The fire service officers training course will be carried out on a winter's afternoon in a hut on a windy hill on Exmoor. This course element includes 10% fast hand movement practice and 90% diversity inclusion training.
Courses can be booked on our website now:
www.giveusyourdosh.com
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I cannot understand why you are so stuck in the past Dr Wiz.
Filament lamps for use with morse code is really old technology and there are much better modern solutions to this outdated technology.
Have you thought of using LEDs instead of filament bulbs?
We thought of the new technology Prof.
The older LED types were not bright enough.
The modern high-brightness versions have too narrow a viewing angle.
But most importantly, we realised the use of filament lamps would keep our system emergency repair facility in continuous work.
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Oh, what are we doing?
Banter in the serious areas?
I can feel an Officer Dibble intervention coming on.
But how refreshing it feels to get back to the good old times - if only for a while.
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Would LED not be more planet saving than filament bulbs? As for the very cleverly spotted brightness issue, potential refuge users should be issued with double rim spectacles.
Can you put me down for the morse code course? Handy for tapping central heating pipes with instructions to wife to bring more beer to tv room and fluff up my cushions. She would hear it anywhere in the house.
Do you think it could be heard over the racket of her using the hoover?