In addition to well-maintained exit routes and fire exits, a properly designed and installed fixed fire suppression system enhances fire protection in the workplace. In some cases, fixed fire suppression equipment is required. Fixed fire suppression systems include automatic sprinkler systems and fixed extinguishing systems.

Automatic sprinkler systems

The most reliable firefighting device for the workplace, and a key fixed fire suppression system, is the automatic sprinkler system. Through the use of properly spaced sprinkler heads and discharge water flow patterns, the system provides complete coverage for a particular workplace.

OSHA regulates the design, maintenance, and testing of automatic sprinkler systems at 1910.159 when they are required by a specific OSHA standard. These include:

• 1910.36 — General requirements — Means of egress
• 1910.106 — Flammable liquids
• 1910.107 — Spray finishing using flammable and combustible materials
• 1910.125 — Additional requirements for dipping and coating operations that use flammable liquids or liquids with flashpoints greater than 199.4 �F (93 �C)
• 1910.109 — Explosives and blasting agents
• 1910.265 — Sawmills

Design requirements

Your automatic sprinkler system must provide complete coverage for the zone it protects. The acceptable designs include:

• Pipe schedule designed systems, which depend on standard-sized pipe, the number of sprinklers, and pipe length to give the proper coverage.
• Hydraulic designed systems, which are based on the engineered design of a pipe size to produce a given water density or flow rate at any particular point in the system.

Design and install your automatic sprinkler system with approved materials. The materials used in your system must meet applicable local fire and building codes.

Water supply

Water supply is an important factor in evaluating the protection of an automatic sprinkler system. No water supply or inadequate water supply means no or an inadequate fire protection. An inadequate water supply can be caused by:

• Improperly closed valves,
• Excessive demand,
• Broken water mains, or
• Broken fire pumps.

The water supply for the automatic sprinkler system must be automatic and must provide the designed water flow for at least 30 minutes. In addition, make an auxiliary supply available in the event that the original water supply is not in service. However, if your automatic sprinkler system consists of 20 or fewer sprinklers, then an auxiliary water supply is not necessary.

Provide equivalent protection when you shut down the primary water supply for the sprinkler system. Equivalent protection could include:

• A fire watch with extinguishers in place and hoses manned.
• A secondary water supply, such as a tank truck and pump.
• A tank or fire pond with fire pumps.

In addition, you may want to evacuate the workplace or have an emergency plan that requires evacuation in the event that the primary water supply is shut down.

OSHA does permit the use of hose connections with the sprinkler system for wet pipe systems when the water supply satisfies combined standpipe and sprinkler demands.

Sprinklers

Use only approved sprinklers in your sprinkler system. If a non-standard sprinkler or part must be used as the replacement part, conduct an engineering review of the altered part of the system. The review must show that the changes to the system will not alter the effectiveness of the system as it is presently designed. Water supplies, water densities, and water flow characteristics should remain the same.

Protect all components, pipes, and sprinklers of the automatic sprinkler system against mechanical impact damage. This protection may include:

• Mechanical guards,
• Mechanical screens, or
• Location of system components in areas where physical contact is not possible.

Spacing, as well as the location of the sprinklers, is important to the protection that the system provides. Space the sprinklers to provide the maximum amount of area protection coverage per sprinkler. The placement of sprinklers should minimize the discharge spray interference by the following:

• Building and structural members, and
• Building contents.

Discharge spray interference can result in damage to unprotected areas because the spray pattern is diverted; therefore, any building or structural obstructions must be considered in the design of the automatic sprinkler system.

Sprinkler alarms

When a system has more than 20 sprinklers, an audible local waterflow alarm is required. The alarm must sound when the waterflow through the system equals the flow from one sprinkler. Use a siren, whistle, flashing light, or similar alerting device as an alarm. The objective is to transmit a recognizable signal to the necessary people. The most popular alarm is the motor gong or bell that sounds when water begins to flow through the system.

Hydraulically designed systems

Make sure the hydraulically designed automatic sprinkler systems, or portions thereof, are identified as such. In addition, indicate the location, number of sprinklers in the hydraulically designed section, and the basis of the design.

Inspection, testing, and maintenance

Ensure the automatic sprinkler system will function in the event of a fire through routine inspections, regular testing, and proper maintenance.

Review the following concerns when inspecting your automatic sprinkler system:

• Are there areas not covered by the system?
• Can the sprinklers distribute their flow properly? Are there any obstructions in the way?
• Have additions been made and do they affect the flow of water or water densities?
• Are materials stored so the clearance distance between sprinklers and the materials below them is more than 18 inches?
• Are the pipes properly secured?
• Are sprinklers properly installed?
• Are the proper sprinklers being used?
• Are the sprinklers coated with deposits?
• Are the sprinklers and pipes corroded?
• Are there any leaks?
• Are the valves for the system opened?

Routine inspections are usually performed by the building owner, but inspections can also be performed by your insurance carrier, the local fire department, or sprinkler contractors.

Another aspect to maintaining an effective automatic sprinkler system is the testing of the system. There are three types of tests:

• Acceptance tests — These tests must be performed before the system is put into service. Invite the installer, designer, your insurance representative, and the local fire department to witness the tests. Include the following as part of the acceptance tests:
  • Flushing of the underground connections,
  • Hydrostatic tests of piping in the system,
  • Air tests in dry-pipe systems,
  • Dry-pipe valve operation, an
  • A test of drainage facilities.

If any problems are found during the tests, they must be corrected before the system can be placed into service.

• Main drain flow test — Annually perform the main drain flow test on each system after the system is in service.
• Opening of inspector’s test valve — Open the inspector’s valve every two years. This step will assure that the sprinkler system is operating properly.

A system loses effectiveness when it has inoperable sprinklers, leaks, or clogged pipes. Proper maintenance procedures are required to keep the automatic sprinkler system at its optimum. The procedures might include the following:

• Procedures for shutting down the sprinkler system;
• Alternate methods of fire protection:
  • A fire watch with extinguisher in place and hoses manned,
  • A secondary water supply, such as a tank truck and pump, or
  • A tank or fire pond with fire pumps;
• Procedures for replacing sprinklers, including information on:
  • Emergency stocks of sprinklers,
  • Types of sprinklers, and
  • Tools used in the replacement of sprinklers;
• Procedures for pipe repairs; and
• Procedures for recording repairs.

Whenever maintenance on the sprinkler system requires the system to be shut off, the safety of the employees must be the main concern. The maintenance work can only be done when the fire hazard exposure to employees is at a minimum. Perform repairs and changes to the system when employees are not working or are not occupying the area protected by the shutdown system.

If this fire prevention technique is not possible, then alternate methods of fire protection are necessary.

Fixed extinguishing systems

As with the automatic sprinkler systems, OSHA only regulates fixed extinguishing systems when you must comply with a standard that requires an extinguishing system. Additionally, OSHA regulates systems that are total flooding, which causes high concentrations of the extinguishing agent to be released. Some of the effects of high concentrations of extinguishing agents include:

• Visual disorientation if a cloud of a dry chemical agent is released.
• Exposure of employees to hazardous combustion by-products when agents come in contact with hot metals or surfaces.
• Exposure to hazardous concentrations of the agent.

Fixed extinguishing systems include dry chemical, gaseous agents, water spray, and foam.

Design requirements

The design of a fixed extinguishing system must be based on the type of fire that the system will control or extinguish. The components of the system must be suitable and approved for use with the specific fire hazard. The suppression agent must also be approved for use with the specific fire hazard. Using improper components or unapproved agents would prevent your fixed extinguishing system from controlling or extinguishing the fire.

The design must consider and/or include, depending on your system, the following elements:

• The climate in which the system must operate — The system must be operable in ambient temperature extremes;
• A corrosive atmosphere — The system must be made of noncorrosive materials or protected against corrosion;
• An automatic detection system that complies with 1910.164;
• At least one manual operating station; and
• A distinctive alarm or warning device that complies with 1910.165.

Automatic detection systems

Fixed extinguishing systems require automatic detection equipment. The purpose of the equipment is to:

• Detect fire,
• Activate the suppression system, and
• Possibly activate an employee alarm system.

This equipment must be approved for the application in which it is used. Like the extinguishing system, the effectiveness of the automatic detection system depends on proper installation and maintenance. A poorly installed or maintained detection system could mean an uncontrolled fire with major damage losses.

Alarm system

Use an alarm or signaling system with your extinguishing system to alert employees that the extinguishing system is discharging. The alarm or signaling system must be a distinctive signal that can be perceived above the ambient noise or light levels in the area. The exception is the system for which the discharge is immediately recognizable.

An acceptable alarm can be any of the following, as long as it is identifiable by employees: bell, gong, whistle, horn, flashing light, or combinations of signals.

Signs and warnings

Post signs or warnings to notify employees of areas protected by fixed extinguishing systems. These signs are required when the concentration of the agent is hazardous to the employees. Post the hazard warning or caution signs at the entrance of the inside of these protected areas.

Use safeguards and warnings to prevent employees from entering discharge areas in which the atmosphere remains hazardous to employee safety and health after discharge.

Mark the manual operating devices to identify the hazard they are protecting against.

Inspections and maintenance

Perform an acceptance test on a new detection system to ensure it is operating properly. The acceptance tests must be performed before the system can be put into service. Invite the installer, designer, your insurance representative, and the local fire department to witness the tests. Any problems found during the acceptance test should be corrected before the system is put into service.

Have a person knowledgeable in the design and function of the system inspect the detection system annually to assure the system is in good operating condition.

If a fixed extinguishing system becomes inoperable, inform your employees of the situation and take temporary precautions to ensure their safety until the system is operable again. Any defects or impairments of the system must be corrected by trained personnel.

Besides the system inspection and maintenance, inspect the suppression agent containers for weight and pressure losses, depending on the type of container. The following table shows the timetable for this inspection.

Keep a record of the inspection and maintenance on the container, on a tag attached to the container, or in a central location. Maintain this record until the next semi-annual check or for the life of the container, whichever is less.

Personal protective equipment (PPE)

If employees rescue a trapped coworker from an area in which a hazardous agent discharge has occurred, PPE is required. The employer must provide, at a minimum, a positive-pressure self-contained breathing apparatus. First aid equipment should also be provided.

Total flooding systems with potential hazards

If you have total flooding systems that provide agent concentrations exceeding the maximum safe levels, then you must have an emergency action plan in accordance with 1910.38. The following are the maximum safe levels:

• Halon 1211 and carbon dioxide systems — less than 4 percent;
• Halon 1301 systems — less than 10 percent;
• Halon 1301 concentrations are not 7 percent or greater, and egress time is not greater than one minute;
• Halon 1301 concentrations are not 10 percent or greater, and egress time is greater than 30 seconds but less than one minute; and
• Halon 1301 concentrations are not 10 percent or greater, and egress time is not greater than 30 seconds.

If the total flooding systems are installed in an area that employees cannot enter during or after system discharge, the system is exempted from these requirements.

A pre-discharge alarm, which can be perceived above the area noise and light levels, is required. It must be actuated before system discharges but must allow for safe egress of employees before the system discharges.

This system must have an automatic actuation device by the means of a fire detection device. The pre-discharge alarm and the fire detection device must be interconnected, so employees can safely exit the discharge area before the system discharges.

Dry chemical fixed extinguishing systems

Dry chemical extinguishing systems use a very small particle chemical with expellant to extinguish a fire. The systems consist of the small particle chemical agent, the expellant, and the actuating devices. The system’s discharging method can be either:

• Total flooding — This system is used when the area being protected is totally enclosed. It discharges a prescribed amount of the suppression agent into the contained area.
• Local application — This system discharges directly into the fire. It is used for situations where the hazard can be isolated, such as an open tank of flammable material.

Dry chemical systems must meet the general requirements for fixed extinguishing systems, as well as specific requirements for dry chemical systems. Comply with the following specific requirements for dry chemical agents:

• Make sure the dry chemical is compatible with any foams or wetting agents with which they are used.
• Do not mix together the dry chemical agents of different compositions.
• Refill the system with the dry chemical agent stated on the name plate or an equivalent compatible material.
• Provide an alarm system if the dry chemical discharge can obscure the vision of employees. This alarm must comply with 1910.165 and must provide employees enough time to exit the area before agent discharge.
• Sample the dry chemical supplies at least annually to determine if the supply is free of moisture. Stored pressure systems are exempt from this sampling.
• Reach the designed concentration of the dry chemical agent within 30 seconds of initial discharge.
• Regularly inspect and maintain the system.

Gaseous agent fixed extinguishing systems

Gaseous agents can be used with fixed extinguishing systems to extinguish fires. The agent is usually in the gaseous state in storage, but there are some in the liquid state during storage. Some of the gaseous agents that are used in this type of system are halons, which are being phased out, and carbon dioxide.

Carbon dioxide is an effective extinguishing agent because it dilutes the oxygen content to the point where the atmosphere no longer supports combustion.

As with the dry chemical extinguishing system, a gaseous agent system must comply with the general requirements for fixed extinguishing systems and the specific requirements for gaseous agents. Comply with the following specific requirements for gaseous agent systems:

• Confirm that the agent’s initial supply and its replenishment supply is an approved type for the system’s application.
• Do not expose employees to toxic concentrations of the agent or its decomposition products.
• Use a pre-discharge alarm that can be perceived above the area noise and light levels. The alarm must be actuated before the system discharges, allowing employees to safely evacuate the discharge area. This requirement is for systems with the following designed discharge concentrations:
  • Halon 1211 and carbon dioxide at a concentration of four percent or greater.
  • Halon 1301 at a concentration of 10 percent or greater.

The following requirements are only for total flooding systems:

• Maintain the designed concentration of the gaseous agent at all times, especially until a fire has been extinguished or is under control. When a system is being overhauled, it is exempt from this requirement
• Attain the designed extinguishing concentration within 30 seconds of initial discharge. Halon systems must reach designed concentration within 10 seconds of initial discharge.

• Use Halon 1301 only under the following conditions:
  • Halon 1301 concentrations are seven percent or less, and egress times are one minute or less.
  • Halon 1301 concentrations are 10 percent or less, and egress times are greater than 30 seconds but less than one minute.
  • Halon 1301 concentrations are greater than 10 percent in an area not normally occupied by employees, and egress times are less than 30 seconds. No unprotected employees can enter the area during discharge.

• Regularly inspect and properly maintain the gaseous agent so it is effective.

Water spray and foam fixed extinguishing systems

The last type of fixed extinguishing system includes the:

• Water spray system — The water spray system extinguishes the fire by dilution, cooling, and smothering. It consists of the following elements:
  • A reliable water source,
  • Nozzles or similar devices,
  • Piping, and
  • A drainage system.
• Foam system — The foam system prevents or stops combustion by forming a blanket between the horizontal surface of the fire. This blanket acts as a coolant, vapor sealant, and barrier between the air and the burning surface. Foam systems consist of the following:
  • A reliable water source,
  • An air supply,
  • A foam generation device,
  • Foam distribution devices, and
  • A drainage system.

Foam systems have definite limitations. Consider the following limitations when selecting the type of foam for the specific hazard:

• Some foams are not acceptable for use on fires involving flammable gases or liquefied gases with boiling points below ambient workplace temperatures.
• Some foams are not effective on polar solvents.
• Foams using water as part of the mixture should not be used on combustible metals. If the temperature of the burning metal is reduced below its ignition temperature, then only authorized foams can be used.
• Certain foams may be incompatible and break down when they are mixed.
• Foams used for water soluble solvents must be tested and approved for such use.

OSHA requires that water spray and foam systems meet the general requirements for fixed extinguishing systems and the specific ones for water spray and foam systems.

If you have a water spray or foam system, comply with the following requirements:

• The design of the system must effectively control the fire in the protected areas or equipment.
• The system must provide for proper drainage facilities for the water or foam. The drainage system must direct the flow of the water or foam:
  • Away from work areas,
  • Away from emergency egress routes, and
  • Toward a central collection area.