Significance of Test. Flash point measures the tendency of the sample to form a flammable mixture with air
under controlled laboratory conditions. Flash point is used in shipping and safety regulations to determine
flammable and combustible materials. Flash point can indicate the possible presence of highly volatile materials
in a relatively nonvolatile material. Fire point measures the characteristics of the sample to support combustion.
Difference. D-92 (Cleveland open cup) is used to determine flash and fire points of all POL products except fuel
oils and products having an open cup flash below 175 degrees Fahrenheit, D-93 (Pensky-Marten) is used mainly
to test flash for fuel oils, D-56 (Tag Closed) is used for liquids that flash below 220 degrees Fahrenheit.
Cloud Point (ASTM D-2500).
Scope. This test method covers only petroleum oils which are transparent in layers of 38 mm (1 1/2 in) in
thickness, and with a cloud point below 49 degrees Celsius (120 degrees Fahrenheit).
Summary of Method. The sample is cooled at a specified rate and examined periodically. The temperature at
which haziness is first observed at the bottom of the test jar is recorded as the cloud point.
Significance of Test. The cloud and pour point of petroleum oil is an index of the lowest temperature of its
utility for certain application.
Pour Point (ASTM D-97).
Scope. This test method is intended for use on any petroleum oil.
Summary of Method. After preliminary heating, the sample is cooled at a specified rate and examined at
intervals of 3 degrees Celsius for flow. The lowest temperature at which movement of the oil is observed is
recorded as the pour point.
Significance of Test. The pour point of a petroleum oil is an index of the lowest temperature of its utility for
certain applications.
Freezing Point (ASTM D-2386).
Scope. This test method covers the determination of the temperature below which solid hydrocarbon crystals
may form in turbine and reciprocating engine fuels.
Summary of Method. A sample of aviation fuel is cooled until crystals of hydrocarbon are formed. The
temperature at which these crystals disappear when the fuel temperature is allowed to rise is recorded as the
freezing point.
Significance of Test. Freezing point of aviation fuels provides guidance as to the lowest temperature of its
utility for certain applications.
Kinematic Viscosity (ASTM D-445).
Scope. This test method covers the determination of the Kinematic viscosity of liquid petroleum products, both
transparent and opaque, by measuring the time for a volume of liquid to flow under gravity through a calibrated
glass capillary viscometer.
Summary of Method. The time is measured in seconds for a fixed volume of liquid to flow under gravity
through the capillary of a calibrated viscometer under a reproducible driving head and at a closely controlled
temperature.
Significance. Many petroleum products, as well as nonpetroleum materials, are used as lubricants for such
things as bearings, gears, compressor cylinders, and hydraulic equipment. The proper operation of the
equipment depends upon the proper viscosity of the liquid. Thus, the accurate measurement of viscosity is
essential to many product specifications.
Copper Corrosion (ASTM D-130).
Scope. This method covers the detection of the corrosiveness to copper of aviation gasoline, aviation turbine
fuel, automotive gasoline, natural gasoline, or any other hydrocarbons having a Reid vapor pressure no greater
than 18 psi.
Summary of Test. A polished copper strip is immersed in a given quantity of sample and heated at a
temperature and for a time characteristic of the material being tested. At the end of this period the copper strip is
removed, washed, and compared with the ASTM copper strip corrosion standard.
Significance. Crude petroleum contains sulfur compounds, most of which are removed during refining.
However, of the sulfur compounds remaining in the petroleum product, some can have a corroding action on
various metals and this corrosive is not necessarily related directly to the total sulfur content.
QM 5184
3-4
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