Introduction to Fire Detection


Introduction to Fire Detection

Fire detection history

In the past, fire prevention devices were not available. Selected members of the community were assigned to monitor the area (especially at night) for fires. If they happen to detect a fire, they would alert people by ringing a church bell or by blowing a unique whistle. Upon hearing the bell or the sound of the whistle, the members of the community would work together to put out the flame.

As time went on, communities grew larger and larger, this system was slowly abolished. In the 1850s a special wooden rattle was invented in Australia that was shaken to alert or to wake people from sleep in the event of a fire.

In 1852, William F. Channing and Moses Farmer developed two fire alarm boxes that contained a telegraphic key. When a fire was detected, someone will quickly crank the handle of the fire alarm box. When this is done, the telegraph in the box instantly sends the fire alarm box number to a general alarm station. As soon as the telegraphers at the central station receive the message, they would notify a fire response team to go to the location of the box.

The first modern high-tech fire alarms were developed in the 21st century. These alarms use modern technologies like private radio system, a cellular transmitter, and digital communicator system. Morden fire alarms can transmit signals to the nearest fire department in a few seconds, after which a fire team will be dispatched.

Smoke detectors are perhaps one of the most important inventions in the twentieth century. Today, smoke detectors come in different shapes and sizes. Some models are designed as plastic enclosures, made in the shape of a disk.

In the 1930s, the first smoke detector was accidentally invented by a Swiss physicist Walter Jaeger. He was initially attempting to build a sensor that could detect poisonous gas. However, when, he lit a cigarette his invention detected the smoke particles that exuded from it.

Smoke detectors were super expensive back in the day, so they were not used commercially. But things changed for the better in 1966, when Duane D. Pearsall and Stanley Bennett Peterson invented the first home smoke detector, which was affordable. Despite the fact that it was cheap, it wasn’t widely used in homes in the US until the early 1990s.

In the 1980s, legislation that required smoke detectors to be installed in every home was passed in the United States. Despite the legislation, people slowly took action. A research that was conducted in 1933 showed that only 92 per cent of homes in the US had smoke detectors. As time when by, more and more people came to see the importance of the device. Today almost every home in the US has a Smoke detector device.

Equipment and tools for detecting fires

Fire detection equipment is a critical part of a building’s safety. When they are working properly, they can alert the residents of a building of a fire before it spreads or gets out of control, given them enough time to escape to safety. Smoke and fire detecting equipment come in different forms; flame detectors, Co2 gas detectors, heat detectors, smoke detector and so on.

Below is an overview of some common fire detection equipment.

Heat detectors

These devices are usually installed in areas with fixed temperatures like- kitchen facilities and small rooms. They should never be installed in areas with fluctuating temperatures. And this is because the alarm embedded in heat detectors are programmed to go off if there is a sudden change in temperature.

Fire detectors

These are devices that are programmed to detect flames. When working properly, they accurately detect the ignition point of a fire. They are used in residential and industrial structures.
Here are the common types of fire detectors.

Infrared Flame detector

They are programmed to monitor the radiation that is generated by flames. They have a response time of two to four seconds. The detector is triggered automatically when there is a sudden change in thermal radiation. Accidental triggers can be decreased with the use of a unique programming algorithm that can recognize the frequency of a flicking flame.

Optical detectors

This is one of the most used flame detectors. They are embedded with special optical sensors for detecting fires. Some optical detectors are designed to detect smoke by means of a principle known as the Tyndall effect.

The detector consists of a dedicated smoke compartment configured as a labyrinth. The chamber is designed to block the entry of ambient light. When smoke enters the chamber, an alarm receptor is triggered.

UV flame detector

An Ultra Violet flame detector device is usually used in high-risk or fire-prone structures, where fires can spread rapidly.

Thermal detector

There are two main types of thermal detectors- thermo-velocimetric detectors and fixed temperature detectors.

Thermo-velocimetric detector- They are programmed to ring out when there is a rapid change in ambient temperature.

Smoke detectors

Smoke detectors are designed to detect fires almost instantly. They are somewhat different from flame detectors.

Below are the types of smoke detectors:

  • Ionization alarms – A small quantity of radioactive material is embedded in these alarms. There are two well-spaced electrodes in the chamber. The radiation allows a small charge to flow between the electrodes in the chamber. If smoke enters the compartment, it quickly absorbs the alpha particles. This, in turn, results in an interruption in the flow of current. When this happens, the alarms will go off.
  • Photoelectric alarms – They operate with the use of photoelectric sensory, a light source, and a beam collimating system. When smoke enters the optical chamber, it obstructs the path of the light beam. This results in the light rays being scattered by the smoke. The scattered light is then beamed to the sensor, which in turns activated the alarm.
  • Combination alarms – These are special smoke detectors that have the features of the photoelectric and ionization alarm technologies. The ionization function responds to intense, high energy flames. The photoelectric function responds to smouldering or low energy flames.

Why smoke detectors are important

Residential fires claim the lives of some 2000 people each year in the United States alone. In a fire, deadly gases and smoke spread a lot faster than heat. Most fire victims don’t die from burns but from continuous inhalation of toxic gasses and smoke.

Most fatal fires occur at night when families and occupants are fast asleep, unaware of the danger that is lurking until it is too late.

A smoke detector stand guards day and night, and when it senses traces of smoke, it sounds an alarm. This allows families the precious time to escape.

A study that was conducted not too long ago shows that two-thirds of fire death occurs in homes with no working smoke detectors.

Where to install a smoke detector

Smoke detectors should be installed in sleeping areas and in every level of a home.

Regular maintenance according to the manufacturer instructions is needed to keep the alarm in great shape.

Important things to keep in mind when installing a smoke detector

Install two or more smoke detectors in your home – Having two or more smoke detectors in your home is a smart move because both of them are less likely to be inoperative at the same time.

Installing a smoke detector – Never should you attempt to install a smoke detector on your own, expect you are a qualified electrician.

Regular test – Test your smoke detectors every month to see if they are working perfectly. Don’t disconnect the batteries when doing this.

Batteries – Whether the batteries in your smoke detectors are weak, it is important that you change them annually. You can ascertain the battery strength of your smoke detector by listening to the beep that indicates a weak battery and replace it immediately.

Cleaning – Follow the manufacturer instructions to the letter when cleaning your smoke detectors. Grease, dust and other materials can cause them to malfunction or operate improperly.

Buy from reputable brands – Only buy smoke detectors from trusted brands. Consult an expert or deep and extensive research to find a top-notch smoke alarm.

Battery powered smoke detectors – Install at least one battery-powered detector in case there is a blackout.

Installation instructions – Make sure you follow the manufacturer installation instructions because no two smoke detector brands are completely the same. Keep in mind that battery powered smoke detector needs to be changed annually. The entire unit should be replaced every 7- 10 years.

Automatic fire detection

Automatic fire detection systems fitted with high tech fire detectors are super effective especially when it comes to detecting smoke and fires.

An automatic fire detection system is made up of the following component.

  • Reception and command switchboard – They act as the fire detection central.
  • Automatic passive devices – These devices are regarded as passive because they can be operated manually.
  • Acoustic and Optical warning devices – Optical indicator and sirens.

Steps to take if you discover a fire in your home or workplace

By nature, fire is destructive, unpredictable and can break out at any time. The steps you take after discovering a fire will determine to a large extent if you will live or die. Below are steps you should take in the event of a fire.

Leave the area – You have a window of two minutes to escape from a burning building. So, if you waste precious time admiring the flame or carry your belonging, you may become trapped. To prevent this, run away from a building or structure when you discover a fire.

Assist others – As you flee to safety after discovering a fire, alert as many people as you can about it and if possible, help them get out of the building. If fire intensifies and the condition becomes unsafe, run out of the building or structure to safety.

Close doors and windows – Closing doors and windows will not only slow down the rate at which the fire spreads, but will also extend a window for the occupants of the building to escape. Don’t open a warm or a hot door, if you do, the raging flames from the other side of the door may engulf you.

Activate the nearest fire alarm – The easiest way to alert the occupant of a building on a fire is by activating the fire alarm in the building. To be on the safe side, it is important that you never ignore a fire alarm, even at night.

Call the authorities – After escaping to safety, call the police or the fire department in your locality and tell them about the nature of the flame and your location. Even if you feel you got things under control, swallow your pride and call the authorities.

Using fire extinguishers – Never should you attempt to use a fire extinguisher unless you have been trained to use it. Using any fire equipment without training may do more harm than good. Since you are not abreast with the working principle of this equipment, you may end up injuring yourself or those around you with it.

Using a portable extinguisher – If you have been trained to use an extinguisher or you have seen first hand how a portable fire extinguisher is used, then you should take action to put the flame out. Using a fire extinguisher is not as complicated as you may be thinking.

Below is a step by step guide on using a fire extinguisher.

  1. Pull the pin on the extinguisher.
  2. Aim the nozzle at the fire.
  3. Slowly squeeze the handle when you are ten feet away from the flame.
  4. Spray and sweep the flame as you approach.

If this doesn’t work or the fire intensifies after doing this, evacuate the building.

Evacuate – In the event of a fire, find the nearest safe exit. Using the elevator is not really a good idea, as it may not function properly especially if the fire is intense.

Report – Ensure that the fire is reported to the police department.

Headcount – Once you are outside, check to see if there is anybody unaccounted for. If there is, notify the firemen and police.

Fire detection is crucial in case of fire, as it can reduce the response time when it matters most. Before detection comes fire prevention – what actions we should take long before a fire starts – and after detection comes fire fighting

I suggest you take the time to read about the main topics I cover on the homepage. There is some life-saving advice. 

Recent Content