Portable Fire Extinguishers
Availability of Portable Fire Extinguishers at UMass Boston
On the UMass Boston campus over 800 portable fire extinguishers have been installed at strategic locations throughout every building. Most of these extinguishers contain either water or carbon dioxide (CO2) extinguishing agents. A small number of multi-purpose, dry chemical extinguishers are also available. Upon special request, extinguishers designed for combustible metal fire fighting have been installed in laboratories. These assorted types of portable fire extinguishers are available for occupant use under the limited conditions discussed below.
When to Fight a Fire With a Portable Fire Extinguisher
It is critical to understand the circumstances under which it is appropriate to attempt to extinguish a fire with an extinguisher. This important "fight-or-flight" decision must include consideration for all of the following factors.
- You know that the fire department is being called. This is accomplished by either activating one of the alarm pull stations (located in corridors) or by calling the campus police on a campus phone by dialing 911. Do not use a public pay phone or your cell phone to call 911. This will waste time and significantly slowdown the process of obtaining emergency fire services.
- You know the building is being evacuated. This is accomplished when you alert everyone within your immediate area to immediately evacuate the building. The Campus Police will continue the evacuation when they arrive on the scene.
- You are trained in the extinguisher's use and feel confident about using it. This is accomplished by being familiar with the different types of fires, fire extinguishers and extinguishing agents. In addition, you must be familiar with the general principles of fire extinguisher use and with incipient- stage firefighting.
- The fire is small and contained. Do not consider fighting a fire unless it is confined to a small area, such as a wastebasket, and it is not spreading. A portable fire extinguisher should only be used for incipient-stage firefighting. An extinguisher is no match for a large or rapidly-advancing fire.
- The exit for your escape is clear and you can fight the fire with your back to the exit. You must always assume that you may not be able to extinguish the fire you are fighting. If the fire does not diminish with your first attack or if any thing goes wrong, immediately leave the building and do not return.
- The proper type of extinguisher is available. Fire extinguishers are designed to fight specific classes of fires. Your selection of an extinguisher to use depends on what is burning.
- You can stay low and avoid breathing smoke. Do not delay your personal evacuation by fighting a fire in an area filled with smoke. Without protective breathing equipment, you could quickly find yourself unable to breathe or see. Smoke can also obscure your exit path.
Fire Extinguisher Maintenance and Inspection
Annual maintenance of the extinguishers is done by a state-certified and DOT-registered service contractor. The services of this contractor, Capitol Fire Co., are coordinated and monitored by the EH&S Office staff. Inspections, which are "quick checks" of the extinguishers to visually determine if they are available and operational, are done in-house. Potentially high hazard areas which include laboratories, facilities' shops and mechanical spaces and kitchens are done on a monthly schedule. These inspections are completed by Fire Extinguisher Liaisons under the direction of EH&S Office staff.
The A, B, C, and D classifications describe a fire's fuel, that is, what is burning. When the classifications are used for rating fire extinguishers, they tell you what classes of fire the various extinguishers should or should not be used on.
- Class A fires involve "ordinary combustibles" - wood, paper, household rubbish, cloth, rubber and many plastics.
- Class B fires involve flammable liquids - oils, greases, tars, oil-based paints, lacquers, flammable gases and some plastics.
- Class C fires involve energized electrical equipment. Note: if the electrical equipment involved in a fire is not energized (e.g., unplugged), the fire becomes either a Class A or a Class B fire.
- Class D fires involve combustible metals such as magnesium, titanium, zirconium, sodium, lithium and potassium.
Fire Extinguisher Classifications, Symbols and Extinguishing Agents
- Class A fire extinguishers: The majority of Class A fire extinguishers available on campus are the 2-1/2 pound pressurized water extinguishers. A few multi-purpose dry chemical extinguishers, also effective for Class A fires, are available. The picture symbol on fire extinguishers suitable for Class A firefighting is a flaming rubbish barrel beside a burning pile of wood. The letter symbol is a triangle containing the letter "A." If colored, the triangle is green.
- Class B fire extinguishers: The majority of Class B fire extinguishers available on campus are the carbon dioxide (CO2) fire extinguishers. A few multi-purpose dry chemical extinguishers, also effective for Class B fires, are available. The picture symbol on fire extinguishers suitable for Class B firefighting is a tipped gasoline can with spout beside a liquid fire. The letter symbol is a square containing the letter "B." If colored, the square is red.
- Class C fire extinguishers: The majority of Class C fire extinguishers available on campus are the carbon dioxide (CO2) fire extinguishers. A few multi-purpose dry chemical extinguishers, also effective for Class C fires, are available. The picture symbol on fire extinguishers suitable for Class C firefighting is an electrical plug and outlet. The letter symbol is a circle containing the letter "C." If colored, the circle is blue.
- Class D fire extinguishers: A few Class D fire extinguishers containing a sodium chloride dry powder extinguishing agent are located in laboratories where combustible metals are used (Note: Lithium fires require a copper extinguishing agent, sodium chloride should not be used). These extinguishers are provided on request. There is no picture symbol for Class D extinguishers. The letter symbol to identify extinguishers suitable for fires involving metals is a five-pointed star containing the letter "D." If colored, the star is yellow.
All fire extinguisher nameplates have either the letter or picture symbols described above. The newer picture symbols use the International sign system diagonal red slash to indicate a potential hazard if the extinguisher is used on that particular type of fire. Absence of a picture symbol means only that the unit is not recommended as particularly effective for that class, but not dangerous if used in error.
Fire Extinguisher Construction
It is important to be familiar with the basic design of portable fire extinguishers. Most extinguishers consist of the basic parts described below.
- Cylinder The body of a typical stored pressure extinguisher is constructed of either low carbon steel or aluminum. The cylinder holds some combination of extinguishing agent and expellant gas.
- Nameplate A large nameplate affixed to the cylinder contains information about operating instructions, the extinguishing agent and the class of fires against which the extinguisher is effective.
- Pressure gauge The operating range of an extinguisher and its ability to expel all of its extinguishing agent decrease as the pressure drops. The pressurized water and multi-purpose dry chemical and sodium chloride dry powder extinguishers all have pressure gauges. These gauges measure the pressure stored inside the extinguisher on a scale calibrated in pounds per square inch. Most pressure gauges are also color-coded so you can tell at a glance if the needle is pointing to the fully-charged or empty range.
- Handle The handle is designed so that you can securely carry and hold an extinguisher while you use it. All handles are located below the trigger. Note: Lifting an extinguisher by the handle will not discharge the unit.
- Trigger The trigger is a short lever mounted above the handle at the top of the extinguisher. Squeezing the trigger releases the extinguishing agent through the hose. Releasing the trigger will stop the release of extinguishing agent.
- Locking mechanism (Pull pin and seal) To prevent accidental discharge, all extinguishers come with a locking mechanism that must be removed before the extinguisher will work. This mechanism is a pin, with a large loop at one end, located below the trigger. You must pull the pin out before you can squeeze the trigger to discharge the extinguisher. Most pins are secured in place by a lightweight plastic tie. This tie serves as a tamper-proof seal and prevents the pin from falling out accidentally. The tie will break easily when you tug on the pin.
- Nozzle or horn The extinguishing agent is expelled from the top of the extinguisher through a hose or a nozzle or cone attached to the extinguisher by a short hose. The pressurized water extinguishers have a hose clip affixed to the cylinder to hold the hose in place. The CO2 extinguishers have a large cone at the end of a short hose that easily identifies them.
How to Operate a Portable Fire Extinguisher
There are four basic steps to operating a portable fire extinguisher. An easy way to remember the procedure is to think of the word "PASS." This general procedure pertains to extinguishers used for Class A, B and C fires. A different procedure is used for Class D fires.
- Pull the pin: Holding the extinguisher with the nozzle pointing away from you, release the locking mechanism. Usually, this means pulling out the pin located below the trigger.
- Aim low: Standing 6 to 8 feet (2-3 meters) away from the fire, point the extinguisher nozzle at the base of the fire--the lowest point of the fire nearest you. Extinguishers are designed to be operated in an upright position. Always hold the extinguisher vertically. Never cradle it horizontally or at an angle in your arms.
- Squeeze the trigger: Squeeze the trigger slowly and evenly. This will release the extinguishing agent and expel it through the nozzle.
- Sweep side to side: As the extinguishing agent is expelled, sweep the nozzle from side to side--"driving the fire back." As the fire closest to you goes out, you may move closer to the fire and continue the sweeping motion until the fire is extinguished. Remember, hold the extinguisher upright. If the fire does not diminish immediately, get out of the building!