Fire extinguishers are common mass produced safety devices that help keep people protected during fire emergencies. But how are they made? Find out below.
What Is a Fire Extinguisher Made Of?
Certain materials are used to construct fire extinguisher components. These are used for good reason. Metal is the primary material used in fire extinguishers, and the most common are aluminum alloy and steel. Plastic is also used in the valve assembly and for more components in less expensive models.
Fire Extinguisher Materials
The materials used in fire extinguishers include:
- Plastic injection molding
- Aluminum alloy
This list does not include the sprayable contents of the fire extinguisher.
Fire Extinguisher Components
Fire extinguishers are made of certain components, which include:
- Squeezable handle or trigger
- Labels and tags
- Safety pin
- Pressure release valve
- Internal tank siphon tube
The canister of the fire extinguisher must be capable of holding stored contents at high pressure. Without this pressure, the fire extinguisher could not release them with enough force to reach the fire. That is why fire extinguisher canisters are made of aluminum alloy, which is both strong and lightweight.
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Fire Extinguisher Manufacturing Process
There are many different types of fire extinguishers, but they are all manufactured in a similar way.
Making The Pressure Canister
Fire extinguisher cylinders are usually made of 1-3 mm aluminum alloy sheets or cylindrical blocks that are molded from two hydraulic presses that perform impact extrusion. This is a two step process where one hydraulic press forms the shape of a pot, and another press then draws the pot into the final cylinder shape. These processes are both done in quick succession and at a close distance and are operated by one or more individuals.
Cylinders can also be formed by rolling steel sheets and welding them together down the center line.
This forms a cylindrical metal form that needs trimming and welding. An edge cutting machine is used to trim the size of the cylinder by firmly holding with a pneumatic fixer and cuts with a blade while the cylinder is rotating. This will make a clean cut around the cylinder for an easy welding process that follows.
A circular MIG welding machine or brazing is then used to permanently attach the bottom of the cylinder.
A threaded collar is added by a press to the cylinder so the valve unit can be attached. The finished cylinder is then hydrostatically tested and cleaned.
The cylinder must then go on to painting. Red powder paint is used which is commonly considered the color of fire extinguishers. The paint is sprayed on using an automatic process in a coating booth whereby the canister is rotated so that every area is covered.
The canisters are then left to cure in an oven before additional components are installed.
This entire process may require up to several hours to complete depending on the manufacturer’s preferred method.
Making the Pressure Release Valve
The release valve is made of aluminum and starts in a cylindrical blank peice that is run through different tooling stations and shaped while applied with lubricant. This process on takes a few minutes
Adding the Fire Extinguisher Handle
The fire extinguisher handle is made of aluminum and is riveted onto the release valve. It is attached with a pin and allowed to pivot. An lever made of aluminum is riveted onto the handle. This is what is squeezed to release the contents of the fire extinguisher.
The Inner Valve Stem
The inner valve stem is what makes the valve function. The first piece is applied by a worker and the valve is run through an essembly machine. A spring is place inside each valve stem which gives the mechanism its resistance when the lever is squeezed. A metal retainer is added that holds the spring and stem together.
Valve And Cylinder Seal
A rubber o-ring is placed by a worker around the valve opening to seal the connection between it and the opening of the cylinder.
The Siphon Tube
The siphon tube connects to the valve and runs down the length of the cylinder where the pressurized contents are stored. The chemicals flow up the siphon tube and out the nozzle attached to the valve unit.
The Fire Extinguisher Guage
The fire extinguisher gauge is screwed onto the valve.
Filling the Cylinder With Contents
The cylinders are first painted and then cooled before the fire extinguishing agents are added. Powders and fluids are added by an automated process.
Installing the Pressure Valve Assembly
The valve assembly is finally added after the contents of the cylinder are added. This is done by a machine which screws the valve unit onto the metal cylinder.
Pressurizing the Cylinder
For dry powder fire extinguishers, pressurized air is added by machine after the valve unit is installed. The valve is left open so the cylinder can be filled.
The pressure gauge will register the increased pressure level and filling continues until the pin aligns with the center of the green zone.
Gas cartridge type fire extinguishers have their cartridge unit added during this process.
Installing the Nozzle and Safety Pin
The final peice to add is the nozzle, which is screwed on and the lever is locked with a pin to prevent accidental discharge.
Adding Fire Extinguisher Labels
Once the fire extinguisher assembly process is near completion, sticker labels are added which give instructions and useful information regarding the type and contents of the fire extinguisher.
Testing and Quality Control
The National Fire Protection Agency (NFPA), Under-writer’s Laboratory, and other organizations in the United States require fire extinguishers be tested and registered before they can be sold. The most critical safety check is the leak test, which makes sure the extinguisher can maintain its pressure and contents.
Fire Extinguisher Labeling
OSHA standard 1910.1200 requires fire extinguishers that store hazardous chemicals be labeled and provide information regarding safety and health procedures. The manufacturing date should also be printed or stamped on the label or cylinder body.
Companies That Manufacture Fire Extinguishers
Today, there are companies that mass produce fire extinguishers for purchase by the public, including:
- United Technologies Corp, Farmington, CT
- Johnson Controls, Milwaukee, WI
- Kidde Fire Protection, West Chester, PA
- Total Safety, Houston, TX
- Amerex Corp., Trussville, AL
- Burner Fire Control, Broussard, LA
- Ansul, Marinette, WI
- American Fire Supply, Fitchburg, MA
- BRK First Alert, Aurora, IL
Fire extinguishers are a fairly simple product to make in terms of time required and quantity of parts to install. However, fire extinguishers must withstand certain performance requirements or they will not be effective when they are most needed during a fire emergency.