Sounding the alarm

Wi-Safe 2 Interlink Diagram With Heat and CO Final No Background for pla...

With growing demand for improved smoke and carbon monoxide detection in homes, wholesalers need to be aware of the types of detectors and alarms available, including those for vulnerable people. Jeremy Roberts, Trade Sales Director of Sprue, explains.

It is very clear that over the coming months and years we will see growing demand for improved protection in homes against fire and carbon monoxide (CO). As a result, wholesalers will need to ensure they are stocking the right products to meet this demand and that they are also armed with the necessary knowledge to advise customers appropriately.

This increased demand is the result of a number of factors. These include recent regulatory changes that require private landlords to include smoke and CO detection in their properties. In parallel, there has been considerable news coverage around the issue of CO, which includes campaigns being run by various TV programmes to encourage people to install CO detectors.

One particularly important area is how to meet the needs of those people who may not be alerted by conventional smoke and CO alarms. These include high-risk individuals such as the deaf, those with mild to moderate hearing loss, children and people who are likely to be under the influence of alcohol or drugs.

For example, research has shown that young people aged between six and 17 years old will not reliably awaken to a conventional smoke alarm signal. Similarly, drinking alcohol significantly affects a person’s ability to wake up in response to an auditory alarm.

To that end, there are a number of ‘assisted living’ products on the market that have been designed to address these issues.

Also, when these products are being used it is important to select the most appropriate types and the ways in which the various devices are connected.

Assisted living devices

As noted above, there are a number of ways in which people can be alerted to an alarm, other than the conventional audible alarms for smoke, heat and CO. For instance, the homes of deaf and hard of hearing people can be equipped with a strobe device that responds to an alarm with a rapid flashing light. Or a vibrating pad located under a pillow or on a chair may be used – or, of course, a combination of the two.

Both of these devices should also be equipped with a visual signal, typically a red LED that indicates whether the danger is from fire or CO.

Another option that is suitable for children, those with mild to moderate hearing loss, older people and people under the influence of alcohol is to use a low frequency signal. This has been shown to be more successful in waking up these high-risk individuals than a standard audible alarm.

A low frequency sounder uses a 520Hz square wave at a volume of 85dB at 3m and, again, is accompanied by a visible red LED light.

When selecting such devices another useful feature is the ability to use the strobe or the low frequency sound as a low level testing device by incorporating a test/reset button that will activate all alarms in the network. This is particularly useful for people with limited physical ability who are unable to access the test/reset button on a ceiling mounted detector.

Interconnected networks

Another issue for wholesalers to consider is how the various devices interact with each other. Historically this would have been achieved through hard-wired networks but increasingly these are being superseded by wireless technology. At the same time, mains-powered alarms are giving way to battery-powered alarms that are able to last for a decade.

These wireless networks offer the same benefits of hard-wired alarms, in that when one goes off all of the other alarms on the network follow suit. Up to 50 alarms can be interlinked in a single wireless network. Each alarm then communicates with others by continuously sending and receiving wireless signals to constantly monitor and communicate with the network.

When any alarm detects smoke, heat or CO the wireless module inside sends a signal to all the connected alarms to ensure a fast reaction across the network.

A useful function in wireless networks is the ability to press the test/reset button on any alarm in the network and silence all but the initiating alarm that sensed the smoke, heat or CO.

A major benefit of using a wireless protection system is that the network can be established very quickly, just a few seconds to follow a simple connection process, and it is very easy to add and remove different devices. For example, if a rented property is equipped with a wireless protection system then it can be easily and cost-effectively reconfigured to suit the assisted living requirements of individual tenants.

Sensor selection

A protection network of this nature can incorporate up to three different types of sensor: smoke, heat and CO.

With smoke alarms it is important to choose the most appropriate sensing technology; in our view this is one that combines optical sensing technology with thermal enhancement to provide a swift reaction to both fast-flaming and slow smouldering fires in a single alarm. Ideally the detector should constantly monitor for temperature change so that if a rate of temperature rise is detected, the sensitivity of the alarm is increased to provide a quicker response time to both types of danger.

Heat alarms are designed for areas where dust and fumes may trigger frequent nuisance alarms in conventional smoke alarms, making them ideal for attics, garages and kitchens. Typically, a heat alarm will activate when the temperature reaches a pre-set range between 54°C and 65°C. This should be combined with constant monitoring for temperature change so that if the temperature is predicted to exceed an alarm trigger threshold, the alarm will sound. Use of a radiant heat dish to reflect heat from a fire onto the thermistor will improve reaction time.

A carbon monoxide alarm uses electrochemical sensors to measure levels of carbon monoxide. It should also maintain a log of alarm events, along with CO levels at the time of the alarm, so that causes can be more easily identified.

Combined or stand-alone

The other issue that customers may ask about is whether to buy separate smoke and CO alarms or whether to use one of the combined units that are now available. Clearly a combined unit offers certain benefits in terms of cost and installation however it’s important to be aware that smoke and CO pose very different threats. The best response to a CO alert is to open the windows to ventilate the room. If there is a fire, though, opening the windows will simply fuel it.

With such a wide range of requirements to address, the key for wholesalers is to ensure they stock a comprehensive range of devices and understand the application of each. In this way, they can provide customers with the most appropriate advice and potentially help to save lives.