Thursday, 21 May 2015

Fire Fighting: Fire First Aid


Understanding Fire

There must be three elements for Combustion to occur. Combined, these are often referred to as the fire triangle or the triangle of combustion. The best method to extinguish a fire is to remove one of the three elements of the fire triangle.

Starvation is the removal of fuel from the vicinity of the fire, which can also be achieved by removing the fire from the vicinity of the fuel.

Smothering is the reduction of oxygen available to fire, which can also be achieved by the application of an extinguishing agent, such as foam.

Cooling is the reduction of temperature below that which is required for combustion.

Combination of methods in many instances is a combination of methods which extinguishes a fire.

Extinguishing Agents

WATER: Because of its availability and cheapness, water is the most commonly used extinguishing agent. Its effectiveness is due to its ability to absorb heat from both the burning fuel and the heated vapour.
FOAM: Fire-fighting foam forms a froth on the surface of a liquid thus denying the fire oxygen and since 90% of the fire-fighting foam is water, foam also reduces temperatures.

CARBON DIOXIDE: At normal temperature and pressure CO2 is a stable gas which will not support combustion. Unfortunately it has one main drawback; it’s extremely low temperature makes it unsuitable for use on electronic equipment such as computers.
DRY CHEMICALS: There are many chemicals which are used as fire extinguishing agents with the additional benefit that they will not conduct electricity, unlike foam and water, but will smother and cool the fire and assist in breaking the chemical chain reaction.

Types of Fires Extinguishers & Uses

Five (5) common types of fire;
- Ordinary combustibles such as wood, paper, plastics etc. Water, foam and dry powder can be used on this type of fire.
- Flammable and combustible liquids -Use dry chemical, foam and CO2.
- Flammable Gases - Use dry chemical.
- Electrical - CO2 and dry chemical can be used for this type of fire, foam and water MUST NEVER be used on electrical fires.
- Cooking oils and Fats - Use dry chemical.


Different kinds of Extinguishers

1. WATER EXTINGUISHERS – COLOR RED
The water stream should be directed at the base of the flames, working from side to side. As the flames diminish, change the stream to a spray (by placing your finger over the nozzle). A spray is more effective in reducing the temperature of the embers.

2. FOAM EXTINGUISHERS – COLOR BLUE
These require a different technique, as the foam must form a blanket on the flammable liquid surface. The jet should therefore be diverted toward the container wall, so that the foam forms a blanket on the surface and the foam build-up is allowed to spread.

3. CO2 – COLOR RED WITH BLACK BAND
With these, the gas should be directed at the near edge of the fire and then passed from side to side in a gentle sweeping action. CO2 can be safely used on electrical fires, as they will not conduct electricity.

4. DRY CHEMICAL – COLOR RED WITH WHITE BAND
The dry chemical should be directed towards the vapour space above the fuel and swept side to side in a rapid motion.

Before using any Extinguisher

1. Check the gauge to see that the extinguisher is fully charged.
2. Shake the extinguisher to loosen the dry chemical powder.
3. Remove the safety pin; and
4. Tests operate the extinguisher to ensure correct operation and to ascertain the throwing distance (with the wind behind your back).

How to Use a Fire Extinguisher

Practicable method of using fire extinguisher is called P.A.S.S. Method;
1. Pull the pin - This will allow you to squeeze the handle in order to discharge the extinguisher.
2. Aim at the base of the fire - Aiming at the middle will do no good; the agent will pass through the flames.
3. Squeeze the handle - This will release the pressurized extinguishing agent.
4. Sweep side to side - Cover the entire area that is on fire. Continue until fire is extinguished. Keep an eye on the area for re-lighting.

What to do in the event of a FIRE

1. Assist persons in immediate danger.
2. Raise the alarm.
3. Assess the fire situation. If safe, attempt to extinguish the fire using the correct extinguisher.
4. Water and electricity are a lethal combination; ensure the power is disconnected before using water or foam on an electrical fire. If it is a fuel fire, turn the source off if possible.
5. Approach the fire from upwind.
6. Keep low, where there is likely to be less smoke.
7. Ensure a safe line of retreat, should the fire get out of control.
8. If you cannot extinguish a fire, account for all personnel in the area, close doors and windows (if possible) and move to a safe location.
9. Ensure all used fire extinguishers are sent for recharge and not placed back on their hooks.

“Do not take unnecessary risks, if the fire is out of control then get out and warn others”

Conclusion

All personnel are expected to perform tasks in a responsible manner to ensure that there is no potential source of ignition in any designated or restricted areas.

The following safe work practices apply to all Oil & Gas sites:
- Observe all “No Smoking” areas, signs forbidding flames and sparks in designated areas.
- Do not smoke within 8 meters of any explosive or within 10 meters whilst refueling any vehicle, in any flammable fluid storage area or whilst working on or near vehicle batteries. Smoking is also prohibited within 45 meters (150 feet) of a drill hole site.
- Do not store flammable materials near timbered areas, electrical equipment or refueling points.
- Spillage of fuel, oils or chemicals must be cleaned up and reported immediately.
- All flammable liquids must be kept in sealed containers during transport and storage.
- Do not store equipment or materials in front of extinguishers or other fire fighting equipment; the appliances must be visible at all times.
- Do not leave rags or other flammable materials on motors.
- Ensure electrical leads and appliances have a current “test tag” and are in good condition and that circuits are not overloaded.
- To work in the oil & gas site, we need to supply our own fire fighting equipment.



~ Culled from HSE articles BlogSpot


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