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Subchapter 7. General Industry Safety Orders
Group 27. Fire Protection
Article 156. Definitions

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§6150. Definitions.

(a) Definitions.

(1) Aqueous Film Forming Foam (AFFF). A fluorinated surfactant with a foam stabilizer which is diluted with water to act as a temporary barrier to exclude air from mixing with the fuel vapor by developing an aqueous film on the fuel surface of some hydrocarbons which is capable of suppressing the generation of fuel vapors.

(2) Automatic Fire Detection Device. A device designed to automatically detect the presence of fire by heat, flame, light, smoke or other products of combustion.

(3) Carbon Dioxide. A colorless, odorless, electrically nonconductive inert gas (chemical formula CO2) that is a medium for extinguishing fires by reducing the concentration of oxygen or fuel vapor in the air to the point where combustion is impossible.

(4) Dry Chemical. An extinguishing agent composed of very small particles of chemicals such as, but not limited to, sodium bicarbonate, potassium bicarbonate, urea-based potassium bicarbonate, potassium chloride, or monoammonium phosphate supplemented by special treatment to provide resistance to packing and moisture absorption (caking) as well as to provide proper flow capabilities. Dry chemical does not include dry powders.

(5) Dry Powder. A compound used to extinguish or control Class D fires.

(6) Extinguisher Rating. The numerical rating given to an extinguisher which indicates the extinguishing potential of the unit based on standardized tests developed by Underwriters Laboratories, Inc.

(7) Fire Extinguishers, Portable.

(A) Portable fire extinguishers are classified for use on certain classes of fires and rated for relative extinguishing effectiveness at a temperature of plus 70 degrees Fahrenheit by nationally recognized testing laboratories. This is based upon the classification of fires and the fire-extinguishment potentials as determined by fire tests.

(B) The classification and rating system described in this standard is that used by Underwriters' Laboratories, Inc., and Underwriters' Laboratories of Canada and is based on extinguishing preplanned fires of determined size and description as follows:

1. Class A Rating--Wood and excelsior.

2. Class B Rating--Two-inch depth n-heptane fires in square pans.

3. Class C Rating--No fire test. Agent must be a nonconductor of electricity.

4. Class D Rating--Special tests on specific combustible metal fires.

(8) Fires.

(A) Class A. Fires in ordinary combustible materials, such as wood, cloth, paper, rubber, and many plastics.

(B) Class B. Fires in flammable or combustible liquids, gases, greases and similar materials and some rubber and plastic materials.

(C) Class C. Fires which involve energized electrical equipment where the electrical nonconductivity of the extinguishing media is of importance. (When electrical equipment is de-energized, extinguishers for Class A or B fires may be used safely.)

(D) Class D. Fires in combustible metals, such as magnesium, titanium, zirconium, sodium, and potassium.

(9) Fixed Extinguishing System. A permanently installed system that either extinguishes or controls a fire at the location of the system.

(10) Foam. A stable aggregation of small bubbles which flow freely over a burning liquid surface and form a coherent blanket which seals combustible vapors and thereby extinguishes the fire.

(11) Gaseous Agent. A fire extinguishing agent which is in the gaseous state at normal room temperature and pressure. It has low viscosity, can expand or contract with changes in pressure and temperature, and has the ability to diffuse readily and to distribute itself uniformly throughout an enclosure.

(12) Halon 1211. A colorless, faintly sweet smelling, electrically nonconductive liquefied gas (chemical formula CBrClF2) which is a medium for extinguishing fires by inhibiting the chemical chain reaction of fuel and oxygen. It is also known as bromochlorodifluoromethane.

(13) Halon 1301. A colorless, odorless, electrically nonconductive gas (chemical formula CBrF3) which is a medium for extinguishing fires by inhibiting the chemical chain reaction of fuel and oxygen. It is also known as bromotrifluoromethane.

(14) Inspection. A visual check of fire protection systems and equipment to ensure that they are in place, charged, and ready for use in the event of fire.

(15) Local Application Systems. A fixed fire suppression system which has a supply of extinguishing agent, with nozzles arranged to discharge extinguishing agent directly on the burning material to extinguish or control a fire.

(16) Maintenance. The performance of services on fire protection equipment and systems to assure that they will perform as designed in the event of a fire. Maintenance differs from inspection in that maintenance requires the checking of internal fittings, devices and agent supplies.

(17) Multipurpose Dry Chemical. A dry chemical which is approved for use on Class A, Class B and Class C fires.

(18) Pre-Discharge Employee Alarm. An alarm which will sound at a set time prior to actual discharge of an extinguishing system so that employees may evacuate the discharge area prior to system discharge.

(19) Small Hose System. A system of hose ranging in diameter from 5/8-inch to 1 1/2-inch (1.8 cm to 3.8 cm) which is for the use of employees and which provides a means for the control and extinguishment of incipient stage fires.

(20) Sprinkler Alarm. A local alarm unit is an assembly of apparatus approved for the service and so constructed and installed that any flow of water from a sprinkler system equal to or greater than that from a single automatic sprinkler will result in an audible alarm signal on the premises.

(21) Sprinkler System. A sprinkler system, for fire protection purposes, is an integrated system of underground and overhead piping designed in accordance with fire protection engineering standards. The installation includes a water supply, such as a gravity tank, fire pump, reservoir or pressure tank and/or connection by underground piping to a city main.

The portion of the sprinkler system above ground is a network of specially sized or hydraulically designed piping installed in a building, structure or area, generally overhead, and to which sprinklers are connected in a systematic pattern. The system includes a controlling valve and a device for actuating an alarm when the system is in operation. The system is usually activated by heat from a fire and discharges water over the fire area.

(22) Standpipes.

(A) Class.

1. Class I. For use by fire departments and those trained in handling heavy fire streams (not less than 2 1/2-inch hose).

Class I Service shall be capable of furnishing the effective fire streams required during the more advanced stages of fire on the inside of buildings or for exposure fire.

2. Class II. For use primarily by the building occupants until the arrival of the fire department (1 1/2-inch hose).

Class II Service shall afford a ready means for the control of incipient fires by the occupants of buildings during working hours, and by watchmen and those present during the night time and holidays.

3. Class III. For use by either fire departments and those trained in handling heavy hose streams or by the building occupants.

Class III Service shall be capable of furnishing the effective fire streams required during the more advanced stages of fire on the inside of buildings as well as providing a ready means for the control of fires by the occupants of the building.

(B) Type. Standpipe systems may be of the following types:

1. Wet standpipe system having supply valve open and water pressure maintained at all times.

2. Standpipe system so arranged through the use of approved devices as to admit water to the system automatically by opening a hose valve.

3. Standpipe system arranged to admit water to the system through manual operation of approved remote control devices located at each hose station.

4. Dry standpipe having no permanent water supply. (Title 24, T8-6150)

(23) Total Flooding System. A fixed suppression system which is arranged to automatically discharge a predetermined concentration of agent into an enclosed space for the purpose of fire extinguishment or control.

NOTE: Authority and reference cited: Section 142.3, Labor Code.


1. New Group 27 (Articles 156-163, Sections 6150-6183) filed 6-20-75; effective thirtieth day thereafter (Register 75, No. 25).

2. Amendment filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).

3. Amendment filed 9-8-81; effective thirtieth day thereafter (Register 81, No. 37).

4. Editorial correction of subsections (a)(12) and (a)(13) filed 6-30-82 (Register 82, No. 27).

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