NFPA 69-1997 Standard on Explosion Prevention Systems

NFPA 69-1997 Standard on Explosion Prevention Systems. 1-8* Inspection and Maintenance. 1-8.1* All systems shall be inspected for operability with the manufacturer’s recommendations. An inspection and preven- tive maintenance schedule shall be established in accordance with the manufacturer’s recommendations. 1-9 Definitions. For the purpose of this standard, the follow- ing terms shall have the meanings given in this section. Approved.* Acceptable to the authority having jurisdic- tion. Authority Having Jurisdiction.* The organization, office, or individual responsible for approving equipment, an installa- tion, or a procedure. Blanketing (or Padding). The technique of maintaining an atmosphere that is either inert or fuel-enriched in the vapor space of a container or vessel. Chemical Isolation. A means of preventing flame front and ignition from being conveyed past a predefined point by injec- tion of a chemical suppressant. Combustible. Capable of undergoing combustion. Combustible Concentration Reduction. The technique of maintaining the concentration of combustible material in a closed space below the lower flammable limit. Combustible Dust. Any finely divided solid material, 420 microns or less in diameter (i.e., material passing through a U.S. No. 40 standard sieve), that presents a fire or explosion hazard when dispersed and ignited in air or other gaseous oxi- dizer. Flame Burning Velocity. The burning velocity of a laminar flame under stated conditions of composition, temperature, and pressure of the unburned gas. Flame Front Diverter. A device that opens in response to the pressure wave preceding the flame front of the deflagra- tion, venting the flame front and pressure wave. Flame Speed. The speed of a flame front relative to a fixed reference point. It is dependent on turbulence, the equip- ment geometry, and the fundamental burning velocity. Flammable Limits.* The minimum and maximum concen- trations of a combustible material in a homogeneous mixture with a gaseous oxidizer that will propagate a flame. Flammable Range. The range of concentrations between the lower and upper flammable limits. Flow Isolation. A method employing equipment and proce- dures that interrupts the flow and prevents pressure rise beyond a point. Fundamental Burning Velocity. The burning velocity of a laminar flame under stated conditions of composition, tem- perature, and pressure of the unburned gas. Gas. The state of matter characterized by complete molec- ular mobility and unlimited expansion; used synonymously with the term “vapor.” Hybrid Mixture. A mixture of a combustible gas with either a combustible dust or combustible mist. Ignition Source Isolation. A method...