We are all familiar with fire alarms and more annoyingly fire alarm tests! We get so used to these that when ever we hear an alarm our first thought (not a good one) is, it must be a test. When it carries on for more than 20 seconds then we tend to re-evaluate our first thought and especially if we are in company, start to assess what everyone else is thinking and doing, and maybe mutter suggestions like ‘I think maybe we should evacuate the building, just in case its not a test’. Recent tragic events should sharpen our responses as we are more aware that time is incredibly precious if it turns out that there is a fire and we need to get out.
The problem with sounder based alarms (bells and sirens), is that the information conveyed is binary – on or off, without any clarification or finesse in the message. So what is required is an alarm that conveys more useful information and a message less easy to ignore. This is where Voice alarm (VA) systems are a huge leap forward, instead of a bell or siren a recorded message is played through loudspeaker systems that are carefully distributed around the building and designed to offer a level of intelligibility measurable against a defined performance specification. So that when the alarm is triggered whatever the location and background noise the message can be heard and understood. Statistically it has been proven that it is much harder to ignore a direct voice command to ‘leave the building by the nearest exit’, than a ringing bell.
Voice alarm systems have several other tricks that raise them above a simple sounder system. In addition to a pre-recorded (usually) evacuation message, there is also a microphone function where specific commands can be given to enhance the effectiveness of any evacuation process. These can usually be directed so that they are heard only in certain applicable areas. Some systems allow for phased evacuation so that those most in danger get the message first. Most VA systems are dual purpose so they can be used for regular ‘Tannoy’ announcements and even back ground music applications in addition to emergency use. This is a great asset as fire alarms in general are expensive but other than in emergencies perform no useful function in their lifespan. In this case they are sometimes referred to as PAVA systems (PA systems and VA in one).
In practice a VA or PAVA system contains most of a fire alarm system, so the sensors, break glass units and fire panel are still there but some or all of the sounders are replaced with the VA part of the system. This means that an upgrade from a standard fire alarm to VA or PAVA system can be done by adding the PAVA control rack and fire rated loudspeakers and associated cabling. All of this is constantly monitored for faults in the same way as a conventional fire detection system.