At what position should the pressure gauge needle of a fire extinguisher indicate normal pressure?
2 Answers
The pressure gauge needle of a fire extinguisher indicates normal pressure when it is in the green zone. The normal pressure value for a fire extinguisher is approximately between 1.2 to 1.5 MPa. If the pressure gauge needle is in the red zone, it means the pressure inside the cylinder is insufficient, indicating that the fire extinguisher cannot be used normally. If the needle is in the yellow zone, it indicates overpressure, which means the pressure is too high and can be dangerous. Fire is a chemical combustion reaction, typically caused by the reaction between oxygen in the air and certain fuels such as wood or gasoline. Of course, wood and gasoline do not spontaneously combust simply by coming into contact with oxygen; combustion only occurs when the fuel is heated to its ignition temperature. A fire extinguisher, also known as a fire cylinder, is a portable firefighting tool. It contains chemicals designed to extinguish fires. The fire extinguisher is a sturdy metal cylinder filled with water or fire-extinguishing materials. When the lever at the top of the cylinder is pressed, the high pressure generated forces the extinguishing agent inside the cylinder to be expelled, similar to how a spray can releases its contents. The function of a fire extinguisher is to displace air, depriving the fire of oxygen and causing it to extinguish. Because carbon dioxide is a gas and leaves no residue, it is particularly useful for electrical fires to avoid damaging equipment.
I remember when I first started driving, I was really worried about the fire extinguisher in my car. That pressure gauge needle, under normal circumstances, must stay within the green zone, which is the middle section of the dial. Why? Because green indicates the pressure is just right—in case of a fire, it can spray out smoothly to extinguish the flames. If the needle leans to the left red zone, it means the pressure is too low and it won't spray at all; if it leans to the right red zone, the pressure is too high and it might explode, injuring you. Every two months, I make time to open the trunk and check, ensuring it stays steady in the green zone. There are quite a few influencing factors, like significant weather changes—summer heat causing expansion and contraction can easily make the needle fluctuate. For safety first, it's recommended that beginners develop the habit of checking the gauge regularly, not waiting until an emergency to regret it. Remember, a tiny needle can be a matter of life and death, and timely replacement or repair can always save you from big trouble.
