Fixed Extinguishing

Definition

Fixed fire extinguishing/suppression systems are commonly used to protect areas containing valuable or critical equipment such as data processing rooms, telecommunication switches, and process control rooms.

Their main function is to quickly extinguish a developing fire and alert occupants before extensive damage occurs by filling the protected area with a gas or chemical extinguishing agent.

Fixed Extinguishing System OSHA Standard

OSHA's fixed extinguishing systems, general standard applies to all employers who have a fixed extinguishing system installed to meet a particular OSHA standard, with the exception of automatic sprinkler systems that are covered by 29 CFR 1910.159.

29 CFR 1910.160 contains specific provisions for any fixed system, regardless of why it was installed, that may expose employees to possible injury, death, or adverse health consequences caused by the extinguishing agent. These systems are only subject to the requirements of 29 CFR 1910.160(b)(4) through 29 CFR 1910.160(b)(7) and (c) of the standard.

System Design and Application

A fire extinguishing systems is an engineered set of components that work together to quickly detect a fire, alert occupants, and extinguish the fire before extensive damage can occur. All system components must be:

• Designed and approved for use on the specific fire hazards they are expected to control or extinguish.
• Protected against corrosion or either made or coated with a non-corrosive material if it may be exposed to a corrosive environment.
• Designed for the climate and temperature extremes to which they will be exposed.

Components of a Fixed System

Typical elements and components include:

1. Discharge Nozzle: Discharge nozzles are used to disperse the extinguishing agent into the protected area.
2. Piping: The piping system is used to transport the extinguishing agent (carbon dioxide, halon, argon, etc) from its storage container to the discharge nozzle.
3. Control Panel: The control panel integrates all devices and displays their operational status and condition.
4. Warning Alarm: Electronic devices that provide an audible or visual alarm when detected. Each area protected by a fixed extinguishing system must have a distinctive alarm or signal which complies with 29 CFR 1910.165 to alert occupants that the system is discharging.
5. Warning and Caution Signs: Hazard warning signs must be posted at the entrance to, and inside, areas protected by fixed extinguishing systems.
6. Fire Detectors: A device that detects fire and causes an alarm signal to be generated. Automatic detection devices sense the smoke, heat, or flames from a fire and initiate an alarm.
7. Pull Station : A device that provides a way to manually discharge the fire extinguishing system. A manual discharge station is a device usually mounted on a wall near the emergency exit(s) which will automatically sound an alarm and release the extinguishing agent.
8. Agent Storage Containers: The storage system discharges agent into the piping and through the discharge nozzles when activated by a manual or automatic device.

Operation, Maintenance, and Testing

Automatic fire suppression systems, particularly the total flooding variety, must be operated properly and regularly maintained and tested to guarantee worker safety and system effectiveness. To ensure your fire extinguishing system will perform as expected in the event of a fire, you are required to:

• Inspect each system annually, and operate and maintain them in a working condition, making sure they are always turned on, except during repairs or maintenance.
• Notify employees and establish measures to guarantee their safety if a fixed extinguishing system becomes inoperable. Fix any defects or impairments by trained personnel.
• Check the weight and pressure of refillable containers at least semiannually. If the container shows a loss in net content, weight, or pressure, it must be subjected to maintenance.
• Assure that factory charged non-refillable containers that have no means of pressure indication are weighed at least semiannually. Replace the container if it shows a loss in net weight.
• Assure that inspection and maintenance dates are recorded and kept until the container is checked again or for the life of the container, whichever is less.
• Train employees designated to inspect, maintain, operate, or repair fixed extinguishing systems. Review their training annually to keep them up-to-date.
• Train all employees with respect to the type of systems installed in the workplace, the hazards involved, proper activation in case of emergency, and the correct response to audible and visual pre-discharge alarms. Provide training for non-English speaking employees in languages understood by the affected employees and other individuals that may be exposed to the hazard.
• Provide and assure the use of personal protective equipment (PPE) for rescuing employees trapped in areas that have become hazardous due to an agent discharge.

Total Flooding Applications

Total Flooding Applications consist of protecting an enclosed space by flooding it with a gas, such as carbon dioxide or halon. This method is used to protect electrical equipment and other types of deep-seated smoldering fires that may re-ignite after the flame has been extinguished. Because these systems can create an oxygen deficit or toxic atmosphere they deserve special attention.

Safety and Health Hazards

The Safety Data Sheet for each extinguishing agent should be available in the workplace. It is important that employees know the potential hazards of the extinguishing agents they may be exposed to and how to protect themselves. Additionally, employees who are likely to enter such areas should receive a basic level of instruction into the operating principles of the system to include alarms and related hazards, as well as evacuation procedures. The two most common extinguishing agents used for total flooding applications are carbon dioxide and halon.

Hazards of Carbon Dioxide and Halon Systems

Agents used for initial supply and replenishment shall be of the type approved for the system's application. Carbon dioxide obtained by dry ice conversion to liquid is not acceptable unless it is processed to remove excess water and oil. Specific hazards include:

• Asphyxiation - Exposure to high concentrations of CO2 gas may create an oxygen-deficient atmosphere.
• Cold Temperature - Direct contact with the vaporizing liquid during discharge can cause frostbite burns to the skin.

Specific halon hazards include:

• Asphyxiation - Exposure to high concentrations of halon can create an oxygen-deficient atmosphere.
• Cold Temperature - Direct contact with the vaporizing liquid during discharge can cause frostbite burns to the skin.

• Central Nervous System (CNS) - Inhaling high concentrations of halon gas can cause dizziness, tingling in extremities and, in severe cases, unconsciousness.
• Cardiovascular Effect - In some people, exposure to halon can cause an increased sensitivity of the heart to adrenaline resulting in irregular heartbeats and, in severe cases, heart attack.

When halon is exposed to temperatures above 900 degrees F. it could break down and create high concentrations of toxic gases.

See the Fixed Extinguishing Systems Checklist.

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