Where should the pressure gauge needle of a fire extinguisher point to indicate normal pressure?
1 Answers
The pressure gauge needle of a fire extinguisher indicates normal pressure when it is in the green zone, with the normal pressure value typically ranging between 1.2-1.5 MPa. If the needle is in the red zone, it signifies insufficient pressure inside the cylinder, meaning the fire extinguisher cannot be used properly. When the needle is in the yellow zone, it indicates overpressure, suggesting the pressure is too high and poses a potential hazard (though slight overpressure may still be considered normal). Specific details are as follows: 1. Combustion Reaction: Fire is a chemical combustion reaction, usually caused by the interaction between oxygen in the air and certain fuels like wood or gasoline. Of course, wood and gasoline do not spontaneously combust simply by coming into contact with air; combustion reactions only occur when the fuel is heated to its ignition temperature. 2. Function of Fire Extinguishers: A fire extinguisher, also known as a fire extinguishing cylinder, is a portable firefighting device. 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 out of the cylinder, similar to how aerosol cans spray materials. The primary function of a fire extinguisher is to displace air, depriving the fire of oxygen and causing it to extinguish. Since carbon dioxide is a gas and leaves no residue, it is particularly useful for electrical fires to avoid damaging equipment.
