Fire extinguishers are not only a need of the industries today, they are also an essential item to be kept at homes, in the cars, on air planes and in the cruise ships for safety and initial attempt to put out the fire that has sprung unexpectedly. The fire extinguisher is not something very hard to distinguish, the unique features such as the red color (most commonly seen), the liquid level indicator and the nozzle makes it easy to be found when a fire has broken out and needs to be controlled. Usually it is kept in easy approach such as in the hallways, stairs and the kitchen, mostly in the areas where a fire could break out. Keeping it within reach makes it easy to control the fire in the initial stages before any huge damage is done.

Different types of chemicals are filled inside a fire extinguisher, basically depending on the application. The handheld fire extinguishers easily available in the hardware stores to be used in the kitchen and garage are filled with pressurized nitrogen or carbon dioxide (CO2) to thrust a fire squelching agent on the fire. The active agent in the extinguisher can be a powder such as potassium bicarbonate (KHCO3), liquid water, fluorocarbon or the propelling agent itself. The most effective fluorocarbon which was used until a short time ago but is now discontinued was the bromochlorodifluoromethane (CF2ClBr) referred as halon 1211. But in 1994, all production of halons was ceased by international agreement because it was found out to be very harmful for the environment. The presence of bromine and chlorine atoms present in it were found to be migrating over time to the atmosphere where they reacted to deplete the ozone layer which is already in a terrible condition.

The rising incidents of the fires at homes usually in the winter season when the water in the tanks usually freezes and the fire sprinklers stop working correctly; it has been advised to home owners to have a fire extinguisher in their homes. Most of the time people use cylinders in the open yard at the back of their homes in winter for barbecue parties and the nitrogen cylinders can be very dangerous to use. Even the normal liquid level indicators stop working correctly due to the extremely low temperature. In such times it is best to use the ultrasonic liquid level indicator to measure the fire extinguishers at homes and other places. This way it can be ensured that the extinguisher is in perfect condition and can be used in case of emergency.