When most people are asked about the fire safety of their building(s), the initial response is usually to refer to fire extinguishers, sprinklers, ceiling mounted ‘spot’ detectors – and maybe the exit signs. Sometimes, they even reference fire doors (that may or may not be propped open with a door-stop).
And don’t get us wrong, all of the above measures are great (except the door-stop, obviously). But are they enough?
As one of the most powerful forces on earth, there is little more dangerous than an uncontrolled fire. Fire can destroy buildings, businesses and lives in a matter of seconds – in the UK alone, there were 752,618 reported building fires for year ending March 2022.
But astonishingly, there’s still very little knowledge surrounding the methods and components that truly keep your buildings and people safe.
And early detection can mean the difference between a minor inconvenience and a full blown disaster.
Or life and death.
Arguably, the most efficient, cost effective and low-maintenance piece of equipment to help with detection of fires, is Linear Heat Detection (LHD). This is because in addition to being highly sensitive to rapid changes in temperature anywhere along the cable, it is quick to install, and needs minimal (if any) maintenance – essentially, LHD is a ‘fit and forget’ piece of life-saving equipment. Until it’s activated, you can completely disregard the fact that it’s there…
So, What Exactly is LHD, and Where Can it be Used?
Often referred to as line type heat detection, LHD is a cable-based type of early fire detection, designed to generate either an alarm, or automatically activate a fire suppression system.
The cable itself acts as a heat detector, so when a physical or electronic change occurs, this is identified anywhere along the cable’s entire length (reaching up to 3km). Once the temperature around the cable reaches a certain threshold, the cable can trigger an alarm and subsequently a suppression system.
In a nutshell, this technology provides a much needed early warning detection of fire and/or overheating.
This means that not only can a fire be detected, but it can also be suppressed, without the need for any human intervention.
Coated in different materials to suit specific applications, LHD cables are suitable for use in the majority of dirty, dusty and hard to maintain environments – including damp, humid and unforgiving conditions. This is because they are unaffected by airflow, dangerous chemicals or toxins, removing the risk of reactive failure and false alarms – potentially leading to huge cost savings.
Typical applications or industries include:
- Energy – this covers all facets of power, such as solar and hydrogen, through to switch gear and electrical, HV/MV transformers, and power/transmission tunnels
- Oil and gas – often coupled with a high-level suppression system, LHD is fundamental in improving safety efficiency within this sector, especially for floating and fixed roof tanks
- Buildings/infrastructure – from car parks to kitchens, LHD is frequently used within major infrastructure applications, such as cold storage, escalators, road and access tunnels, server rooms, ceiling voids, cable trays and rail/metro stations
- Industrial – particularly useful in environmentally challenging, hazardous and access restricted areas, LHD is perfect for use in control panels, conveyor belts, waste recycling, distilleries, and ships/marine applications
What’s the Difference Between Digital (Fixed Activation Temperature) and Analogue (Programmable Temperature Sensing) Linear Heat Detection?
The main difference between digital and analogue, is that while both systems are triggered by heat, analogue uses the polymer resistance change to activate the alarm, and digital uses the physical melting of the polymer to activate the alarm.
Digital
As highlighted above, digital linear heat detection cable is often referred to as non-resettable – due to the reference within the European EN54 standards. This is because a physical change takes place in the detection cable once the alarm temperature is reached, and to reset the system, the activated section of cable must be replaced following a fire or overheat condition.
Digital LHD is made up of two metal core wires that come into contact at a certain temperature and, in doing so, create a short circuit. This triggers a resulting alarm on the interface unit or fire control panel.
Essentially, LHD is digital when it can only be in two states – either ‘off’, or ‘alarmed’. There is no in-between stage, and it can’t be reverted to ‘off’ once it has become alarmed.
Analogue
Analogue linear heat detection cable is commonly known as resettable line-type heat detection, as the system can be restored following the event of a fire – providing the detection cable is not exposed to a temperature above 125 ⁰C.
Rather than a physical change taking place, the control unit measures for changes in resistance along the entire length of cable. An alarm is triggered once the resistance along the cable falls below a threshold determined by the chosen alarm temperature setting.
So, Ultimately, the Benefits are..?
As well as the obvious benefit of providing extra protection against the impacts of fire, one of the main advantages of linear heat detection cable is its versatility. It can be installed in both indoor and outdoor environments and in hazardous areas if required. And more importantly, it is unaffected by dirt, dust, debris, damp and time – which means it’s both cost effective, and low maintenance.
Cost/Value Benefits:
- Low installation costs and minimal maintenance effort versus alternative technologies
- Less labour required to install when compared to spot heat detection
- Cable does not require maintenance
- Will not false alarm in dusty or dirty environments, which prevents emergency service callouts, fines, and wasted time
Functionality Benefits:
- Can be positioned directly onto the asset being protected
- Analogue technology is programmable to alarm temperatures, with pre-alarm options
- Digital technology can locate alarm location at any point along the length of cable from exposure to a tiny flame
Installation/Environmental Benefits
- Range of alarm temperatures available to suit a wide scope of ambient conditions
- Safe to install outdoors or in cold storage/freezers down to -40degC (-40degF)
- High temperature variants suitable for ambient temperatures up to +170degC (338degF)
- Can be subject to differing temperatures along the length of the cable
- Can be installed outdoors in direct sunlight
- Cable coating materials available to offer chemical and oil resistance
- Can resist mechanical abrasion with stainless steel braiding options
Although it is perfect for multiple applications, and can be a hugely effective part of your fire strategy, linear heat detection is often overlooked when considering the safety of your buildings/apparatus, and that is because it isn’t spoken about enough. People simply aren’t aware of its existence.
We are here to change that.
You can find out more by clicking here.
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If you need any help or advice in determining whether linear heat detection could be an option for you, don’t hesitate to contact us for a confidential, no-commitment chat.
