We can easily find fire extinguishers everywhere, from buildings, apartments, houses, offices, schools, hospitals, etc. And those places are often equipped with the two most popular types of fire extinguishers. Those are dry powder fire extinguishers and CO2 fire extinguishers. So how do we distinguish and use these two types of extinguishers differently?
Distinguishing Between Dry Powder Fire Extinguisher and CO2 Fire Extinguisher:
To differentiate these two types of fire extinguishers, we can classify them based on their external characteristics.
Firstly, the labeling on the extinguisher can be used to distinguish them.
On a CO2 fire extinguisher, you will often see symbols like MT3 or MT5. These symbols are specific to CO2 extinguishers. “MT” indicates that the chemical agent inside the extinguisher is CO2, and the number following “MT” represents the weight of CO2 gas compressed inside the cylinder. This weight does not include the weight of the cylinder itself. For example, if the fire extinguisher has the symbol MT3, it means the extinguisher contains CO2 gas and has 3kg of compressed CO2.
On a dry powder fire extinguisher, the label will show “MFZ,” indicating that it uses N2 gas to propel the powder into the extinguisher.
Another external feature is that dry powder extinguishers have a pressure gauge on the neck, while CO2 extinguishers do not.
The third distinguishing feature is the nozzle: the nozzle on a dry powder fire extinguisher is soft and small, whereas the nozzle on a CO2 extinguisher is larger and rigid.
Fire Extinguishing Mechanism:
The dry powder fire extinguisher uses pressure to expel the dry powder, isolating oxygen from the burning material, but it may not completely extinguish the fire and there is a risk of reignition with solid materials. On the other hand, the CO2 fire extinguisher uses compressed gas. When activated, CO2 is expelled, rapidly cooling the fire and extinguishing it, but it may not completely put out the fire and there is also a risk of reignition for solid materials.
Steps for Using a Fire Extinguisher: 3.1. Steps for Using a Dry Powder Fire Extinguisher:
There are 4 steps to using a dry powder fire extinguisher.
Step 1: Check the pressure gauge. If the needle points to the green zone, the pressure inside the extinguisher is good. If the needle points to the yellow zone, it indicates overpressure, which is a rare situation that could cause the extinguisher to explode. If the needle points to the red zone, it means the pressure inside is low, and if it points further into the red zone, the extinguisher is empty and cannot be used.
Step 2: Shake the extinguisher. When the extinguisher is static, the contents separate into two layers: the top layer is nitrogen gas and the bottom layer is dry powder. Hold the handle with your dominant hand and the bottom of the extinguisher with the other hand, shaking it vigorously 3 to 5 times.
Step 3: Remove the safety pin. Place your left hand on the neck of the extinguisher, and use your other hand’s index finger to pull the safety pin firmly and decisively. Note: Do not hold the handle when pulling the pin, as this locks the mechanism and prevents the safety pin from being removed.
Step 4: Extinguish the fire. Hold the nozzle close to the fire’s center, not the hose or nozzle itself, as holding these parts could cause the nozzle to spin, making it less effective. Stand about 1.5 to 2 meters from the fire, and use your other hand to press the handle firmly until the fire is out.
Dry powder extinguishers should not be used in areas with machinery, modern equipment, or kitchens, as the powder is highly corrosive and can damage equipment. Food and water contaminated with fire-fighting powder should not be consumed.
Steps for Using a CO2 Fire Extinguisher:
The steps for using a CO2 fire extinguisher are fewer than those for a dry powder extinguisher, but they come with higher risks due to the extremely cold temperature of the CO2 (about -79°C). Holding the nozzle or hose during operation can cause frostbite or skin tissue damage.
Here’s how to use a CO2 fire extinguisher safely:
Step 1: Lift the nozzle to a 90-degree angle.
Step 2: Remove the safety pin. This step is done the same way as with a dry powder extinguisher: place your left hand on the neck of the extinguisher and pull the safety pin with your other hand firmly and decisively.
Step 3: Extinguish the fire. Hold the nozzle with your dominant hand, while your other hand supports the bottom of the extinguisher. Aim the nozzle at the center of the fire, standing about 1.5 to 2 meters away. Press the handle until the fire is out.