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Automatic fire protection
August 2018, IS & Ex


When an insurance company evaluates a business facility, key infrastructure areas are given special attention to reduce the risk in the event of a fire. These include IT equipment, warehousing, substations, archive areas and the like. The next step is to call out a fire specialist to provide advice. This is when terms like ‘fire suppression’ and ‘fire extinguishing’ get bandied about.

So what are the most common terms used and what do they mean, without all the scientific and technical jargon?

Fire protection

This is a broad term that refers to anything relating to the mitigation of unwanted fires. It includes properly designed buildings and the use of appropriate materials, smoke control systems, automatic smoke detectors, passive fire protection (e.g. fireproof coatings etc.), automatic extinguishing systems and so forth.

Fire suppression

The term refers to systems that suppress a fire. The primary aim is to mitigate the spread of fire giving enough time for the fire brigade to arrive. It is a control mechanism to minimise the consequences of a fire. Typically, water-based sprinkler systems fall into this category. Usually these systems are activated when the fire has escalated into a flame. It is typical at this point that sufficient energy is released to raise the temperature of sprinkler bulbs.

Fire detection

These are the systems designed to sense fire. The simplest are the human senses such as smell, touch and sight, which causes someone to raise an alarm. Automatic fire detection includes sensors that are placed around a building waiting for the earliest signs of smoke. Typically, these are those plastic circular devices located on ceilings which are referred to as point type detectors. The most common is an optical point type detector that senses smoke. Others include heat detectors, which either look at how fast the temperature is increasing (rate of rise), or they will trigger at a prescribed temperature set point.

Most manufacturers have sophisticated point type detectors that can sense multiple different phenomena such as a combination of heat and smoke. Some have gone so far as to include audible tones and visual alarms in the detector. Other means of detection, which would require other devices entirely, are air sampling devices, beam detection, linear heat sensing cable, infrared sensing devices, UV sensing devices and so forth. In a nutshell, the term fire detection refers to all of them. The aim of the detection system is to raise an alarm so that persons can evacuate the situation and also to notify the fire brigade if necessary.

Fire extinguishing

This refers to systems that are designed to put out a fire. There are two groups. The first, and most familiar, is handheld equipment such as dry chemical powder extinguishers or CO2 extinguishers. Their proper use requires training.

The second, and perhaps least known, are the automatic extinguishing systems. These include the gaseous fire extinguishing systems that are typically used in data centres, telecoms facilities, archive stores, substations, cable tunnels, museums, ships and so forth. What is important to note is that they are not all the same. There are two families of gases within this group, the inert gas blends and the hydrofluorocarbons. The inert gas types usually consist of argon and nitrogen, two components that already exist in air. They are non-toxic, produce no hazardous by-products, and have no global warming footprint or ozone depleting potential. They are safe to humans, produce no obscuring cloud, and extinguish a fire by starving it of oxygen.

The other class of gases are the hydrofluorocarbons, which are governed by legislation since they are greenhouse gases. The EU has put onerous cradle-to-grave costs on such systems because of their high carbon footprint. HFC227ea has a carbon footprint of 3,5 tonnes, which means 1 kg of it equates to releasing 3,5 tonnes of CO2 into the atmosphere. When putting this into a real application context, a 100 cubic metre server room for example equates to a carbon footprint of 210 tonnes for a non-producing activity. Not very environmentally friendly and could clash with environmental policy. In addition, this family of gases do produce an obscuring cloud on discharge, which could impede someone finding their way to an exit. They can also break down into hazardous by-products such as hydrogen fluoride, which is both toxic to humans and corrosive to equipment. Others break down into Perfluoropropionic acid, which can attack a person’s mucous membranes. Such gases do put out fires, but there are trade-offs that need to be considered.

There is another class of fire extinguishing systems for in-cabinet fire protection using aerosol type extinguishers. These will be covered in another article to be published soon www.facebook.com/astafrica/?ref=settings


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Supplied By: Alien Systems & Technologies
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Further reading:

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    The new SLC4 is Banner’s most compact safety light curtain to date. It has a low-profile design and a sensing area that extends the entire length of its 160 mm housing. This Type 4 safety light curtain ...
  • Wise choices to decrease fire risk and improve safety
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    Fire safety at the workplace is a topic that is easily neglected and many businesses do not devote enough attention to it. The topic quickly becomes top of mind when people lose their lives, or when a building or substantial part of an industrial plant is destroyed by fire.
  • Network-based process visualisation
    November 2018, Pepperl+Fuchs, IS & Ex
    IT technologies such as PC and server virtualisation are establishing themselves in larger plants in the process industry to reduce the growing number of PC hardware components, while at the same time increasing flexibility and availability.
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    As the year draws to a close, it is natural that people start looking forward to the holidays. It is therefore quite easy to neglect to consider the damaging effect a fire could have on businesses during ...
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    The rise of robots has ushered in an increased demand for light curtains that provide a safe environment between the robotic work cells and the rest of the plant. The Allen-Bradley GuardShield 450L safety ...
  • AST’s automated fire extinguishing systems
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  • Pyrogen system ideal for fire protection in cabinet systems
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    Method of operation Pyrogen is the ideal choice for in-cabinet systems. It is essentially a non-pressurised canister that contains a potent fire extinguishing compound that consists primarily of potassium. ...
  • How to choose an industrial safety controller
    September 2018, Turck Banner, IS & Ex
    The following are five key features to look for in a safety controller that will save time and money, as well as help ensure that operators are using the safety system correctly. As with any safety application, ...
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    Extech Safety Systems has partnered with GoRugged to distribute i.safe Mobile products in sub-Saharan Africa. The IS520.1 is an industrial smartphone with current technology for use in Zone 1/21. It combines ...

 
 
         
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