Page 9 - Handbook of Hazardous Chemical Properties

GLOSSARY OF TERMS
Boiling Point at 1 atm - Defined as the characteristic temperature of a liquid when its vapor pressure
is 1 atm. As an example, when water is heated to 100°C (212”F), its vapor pressure rises to 1 atm and
the liquid boils. The boiling point at 1 am indicates whether the liquid will boil and become a gas at
any particular temperature and at sea-level atmospheric pressure.

Burning Rate - Defined as the rate (in millimeters per minute) at which a pool of liquid decreases as
the liquid burns. Details of measurements are provided by D. S. Burgess, A. Strasser, and J. Grumer,
‘‘Diffusive Burning of Liquid Fuels in Open Trays,” Fire Research Abstracts and Reviews, 3, 177
(1961).

Flammable Limits in Air - This is a concentration expressed as percent by volume of the chemical in
air, whereby spontaneous combustion will be supported. The lowest concentration where combustion
will be supported is known as the lower flammability limit (LFL) or lower explosion limit (LEL). LEL
and LFL are considered interchangeable. The upper concentration limit is the UFL (Upper
Flammability Limit) or UEL (Upper Explosion Limit).

Flammability Range - Defined as the difference between the UEL and LEL. This difference is an
indication of how wide the flammability limits of a chemical are. The wider this range, the more
hazardous the chemical may be considered from a fire standpoint.

Flash Point - The flash point of a material is the lowest temperature at which vapors above a volatile
substance will ignite in air when exposed to a flame. Depending on the test method used, the value of
flash point temperature is either Tag Closed Cup (CC) based on ASTM D56 test method, or Cleveland
Open Cup (CC) based on ASTM 093. The value provides a relative indication of the flammability of
the chemical.

Freezing Point - Defined as the temperature at which a liquid changes from liquid to solid state. For
example, liquid water changes to solid ice at 0 “C (32 OF). Some liquids solidify very slowly even when
cooled below their freezing point. When liquids are not pure, their freezing points are lowered slightly.

Heat of Combustion - Defined as the amount of heat liberated when the specific weight is burned in
oxygen at 25 ‘C. The products of combustion are assumed to remain as gases, and the value given is
referred to as the “lower heat value”. A negative sign before the value indicates that heat is given off
when the chemical burns. Three sets of units are given: Btu per pound, calories per gram, and joules
per kilogram.
Heat of Decomposition - Defined as the amount of heat liberated when the specified weight
decomposes to more stable substances. This value is given for very few chemicals , because most are
stable and do not decompose under the conditions of temperature and pressure they are normally
handled under. A negative sign before a value indicates that heat is given off during the decomposition.
The value does not include the heat that is given off when the chemical burns. Three sets of units are
given: Btu per pound, calories per gram, and joules per kilogram.

Ignition Temperature - This is defined as the minimum temperature at which a chemical substance
will ignite without a spark or flame being present. Along with the values of flash point and flammability
range, it provides and indication of the relative fire potential for the chemical.
Late Toxicity - Where there is evidence that a chemical can cause cancer, mutagenic effects,
teratogenic effects, or delayed injury to vital organs such as the liver or kidney, a qualitative description
of the chemical is given. The term implies long-term or chronic effects due to exposure to the chemical.