CLOSED CUP FLASHPOINT: A lowest temperature at which a combustible liquid under prescribed conditions will give off a flammable vapor which will propagate a flame. The tag closed cup tester shall be authoritative for liquids having a flashpoint below one hundred seventy five degrees Fahrenheit (175°F). The Pensky-Martens tester shall be authoritative for liquids having flashpoints between one hundred seventy five degrees Fahrenheit (175°F) and three hundred degrees Fahrenheit (300°F).
DECIBEL: A unit of measurement of the intensity or loudness of sound. Sound level meters employed to measure the intensity of sound are calibrated in "decibels". A "decibel" is technically defined as twenty (20) times the logarithm to the base ten (10) of the ratio of the sound pressure in microbars to a reference pressure of 0.0002 microbar.
DISPLACEMENT (EARTH): The amplitude or intensity of an earthborn vibration measured in inches. The "displacement" or amplitude is one-half (1/2) the total earth movement.
EARTHBORN VIBRATIONS: A cyclic movement of the earth due to the propagation of mechanical energy.
EQUIVALENT OPACITY: The shade on the Ringelmann chart that most closely corresponds to the density of smoke, other than black or gray.
FREE BURNING: A rate of combustion described by material which burns actively and easily supports combustion. Examples: coal, charcoal.
FREQUENCY (VIBRATION AND SOUND): The number of oscillations per second involved in a vibration or sound.
IMPACT NOISE: A short duration sound which is incapable of being accurately measured on a sound level meter.
IMPULSE: Discrete vibration pulsations occurring no more often than one per second.
INCOMBUSTIBLE: A material which will not ignite nor actively support combustion during an exposure for five (5) minutes to a temperature of one thousand two hundred degrees Fahrenheit (1,200°F).
INTENSE BURNING: A rate of combustion described by a material that burns with a high degree of activity and is consumed rapidly. Examples: sawdust, magnesium (powder, flaked or strips), rocket fuels.
MODERATE BURNING: A rate of combustion described by a material which supports combustion and is consumed slowly as it burns. Examples: wood timber and logs.
OCTAVE BAND: A prescribed interval of sound frequencies which classifies sound according to its pitch.
OCTAVE BAND FILTER: An electronic frequency analyzer designed according to standards of the American Standards Association, and used in conjunction with a sound level meter to take measurements of sound pressure level in specific octave bands.
ODOR THRESHOLD: The lowest concentration of odorous matter in air that will produce an olfactory response in a human being. "Odor thresholds" shall be determined in accordance with ASTM method D1391-57 "Standard Method For Measurement Of Odor In Atmospheres (Dilution Method)".
ODOROUS MATTER: Any material that produces an olfactory response among human beings.
PARTICULATE MATTER: Material other than water which is suspended in or discharged into the atmosphere in a finely divided form, as a liquid; or solid at outdoor ambient conditions.
PREFERRED FREQUENCIES: A set of octave bands described by the band center frequency and standardized by the American Standards Association in ASA standard no. S1.6-1960, "preferred frequencies for acoustical measurements".
PRE-1960 OCTAVE BANDS: The frequency intervals prescribed by the American Standards Association in ASA standard 224.10-1953, "octave band filter set".
RINGELMANN CHART: A chart described by the U.S. bureau of mines in their information circular no. 6888, upon which are illustrated graduated shades of gray for use in estimating the light obscuration capacity of smoke.
RINGELMANN NUMBER: The number of the area on the Ringelmann chart that coincides most nearly with the visual density or equivalent opacity of the emission of smoke observed.
SLOW BURNING: A rate of combustion which describes materials that do not in themselves constitute an active fuel for the spread of combustion. Examples: wood, materials with fire retardant treatments.
SMOKE: Small gasborne particles, other than water, that form a visible plume in the air.
SOUND LEVEL METER: An instrument for the measurement of sound pressure levels constructed in accordance with the standards of the American Standards Association, and calibrated in decibels.
SOUND PRESSURE LEVEL: The intensity of sound or noise in decibels.
THREE COMPONENT MEASURING SYSTEM: An instrument or complement of instruments which records earthborn vibration simultaneously in three (3) mutually perpendicular directions.
TOXIC MATTER: Materials which are capable of causing injury to living organisms by chemical means when present in relatively small amounts.
VIBRATION: The periodic displacement of the ground, measured in inches. (Ord., 4-1-1973)