Fire Extinguishers


DOES YOUR VEHICLE HAVE A FIRE EXTINGUISHER? DO YOU KNOW HOW TO USE IT? IS IT IN WORKING CONDITION?

Fire Extinguishers
Fire Extinguishers

A fire extinguisher is an active fire protection device used to extinguish or control a fire, often in emergency situations.

Typically a fire extinguisher consists of a handheld cylindrical pressure vessel, containing an agent which can be discharged to extinguish a fire.

Usage

The typical steps for operating a fire extinguisher (described by the acronym 'PASS') are the following:

  • P - Pull the safety pin.
  • A - Aim the nozzle at the base of the fire, from a safe distance.
  • S - Squeeze the handles.
  • S - Sweep the extinguisher from side to side while aiming at the base of the fire

There are various types of extinguishers which are used for different types of fires; using the wrong type can increase the fire hazard and be hazardous in itself. But using the right one can better the situation. Note also that you should only attack the fire if you're trained and it is safe to do so.

History

The modern fire extinguisher was invented by British Captain George William Manby in 1818. It consisted of a copper vessel of three gallons (13.6-litres) of pearl ash (potassium carbonate) solution contained within compressed air.

The soda-acid extinguisher was invented in the 19th Century and contained a cylinder of one or two gallons of water mixed with sodium bicarbonate. A vial was suspended in the cylinder containing concentrated sulphuric acid. Depending on the type of extinguisher, the vial of acid could be broken in one of two ways. One used a plunger to break the vial, while the other released a lead bung that held the vial closed. Once the acid was mixed with the bicarbonate solution, carbon dioxide gas was expelled and thereby pressurised the water. The pressurised water was forced from the canister through a nozzle or alternatively short length of hose.

Around 1912 Pyrene invented the carbon tetrachloride or CTC extinguisher, which expelled the liquid from a brass or chrome container by a hand pump; it was usually of one imperial quart (1.1-litres) or one imperial pint (0.6-litres) capacity, but was also available in up to two imperial gallon (9-litre) sizes. The CTC vapourised and extinguished the flames by chemical reaction. The extinguisher was suitable for liquid and electrical fires, and was popular in motor vehicles for the next 60 years.

The vapour and combustion by-products were highly toxic though, and could cause death in confined spaces.

Chemistries

A fire extinguisher may emit a solid, liquid, or gaseous chemical.

Installation

Installation of fire extinguishers in vehicles and pleasure craft needs to be in accordance with NZS 4503, pg 34 3.10 and pg 35, table 3.4. Fire extinguishers are typically fitted in buildings at an easily-accessible location, such as against a wall in a high-traffic area. They are also often fitted to motor vehicles, water craft and aircraft, as required by law in many jurisdictions for identified classes of vehicle. Under NFPA 10, all commercial vehicles must carry at least one fire extinguisher (the size/UL rating is depending on the type of vehicle and cargo (eg. a fuel tanker typically must have a 20lb (9kg), when most other vehicles can carry a 5lb (2.3kg) extinguisher).

Maintenance

Most countries in the world require regular fire extinguisher maintenance by a competent person. This allows fire equipment to operate safely and effectively, as part of the requirements under NZS 4503. A lack of maintenance can lead to an extinguisher not discharging when required, or rupturing when pressurised. Deaths have occurred – even in recent times – from unmaintained, corroded extinguishers exploding.

Fire Extinguishers are maintained in accordance with NZS 4503 section 6. All Inspection and maintenance of hand-held operating equipment, with the exception of monthly checks, must be carried out by a competent person.

Basic Service: All types of extinguisher require a basic inspection annually to check operational condition as required by NZS54503 (pg 52 table 6.2, item 6.2.1).

Extended Service: Wet chemical and foam type fire extinguishers require a three-yearly service. This includes a more detailed examination involving a test discharge of the extinguisher and recharging if satisfactory.

Five-yearly Pressure Testing: All fire extinguishers are subject to pressure vessel safety legislation and must be hydraulically pressure tested, date stamped or labeled every five years.

Contact your local TWL outlet for the flame-fighter extinguisher that best meets your needs. Ph 0508 677 704 

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