Procedure: From a temperature 100° F or more
below its anticipated flash point, the sample Is
heated at a prescribed rate. At each multiple of
5° F temperature rise, the lighted torch is
passed over the top of the cup. The test for flash
point is completed when the torch produces a
flash from the vaporized portion of the sample.
below its anticipated flash point, the sample Is
heated at a prescribed rate. At each multiple of
5° F temperature rise, the lighted torch is
passed over the top of the cup. The test for flash
point is completed when the torch produces a
flash from the vaporized portion of the sample.
The same procedure is extended to determine
the fire point. When the flame produced by
igniting the mixture of air and vaporized oil
continues for at least 5 seconds, the fire point
has been reached. For either test, it should be
obvious that complete freedom from drafts is
essential to prevent excessive dissipation of the
vaporized liquid. For precision and consistent
results, the test is usually carried out is a dark-
ened room so that flash can be more readily
observed.
the fire point. When the flame produced by
igniting the mixture of air and vaporized oil
continues for at least 5 seconds, the fire point
has been reached. For either test, it should be
obvious that complete freedom from drafts is
essential to prevent excessive dissipation of the
vaporized liquid. For precision and consistent
results, the test is usually carried out is a dark-
ened room so that flash can be more readily
observed.
Reporting The Results: Flash point is reported
as the temperature at which flash fire occurs,
the fire point is reported as the temperature at
which the flame persists for 5 seconds or more.
as the temperature at which flash fire occurs,
the fire point is reported as the temperature at
which the flame persists for 5 seconds or more.
Significance Of Test Results: To appreciate
the significance of flash point and fire point test
results, one must realize what the tests mea-
sure. It is necessary to understand how a
combustible air-fuel mixture is created.
the significance of flash point and fire point test
results, one must realize what the tests mea-
sure. It is necessary to understand how a
combustible air-fuel mixture is created.
For all practical purposes, a petroleum liquid
does not burn as such, but must first be vapor-
ized. The vapor mixes with the oxygen in the air,
and, when sufficient concentration of the vapor
is reached, the mixture may be ignited, as by a
spark or open flame. The mixture can be ignited
only if the concentration of fuel vapor in the air
is more than about 1% or less than about 6% by
volume. A confined mixture containing more
than 6% fuel vapor becomes a practical
explosion hazard only if it is vented to admit a
greater portion of air.
does not burn as such, but must first be vapor-
ized. The vapor mixes with the oxygen in the air,
and, when sufficient concentration of the vapor
is reached, the mixture may be ignited, as by a
spark or open flame. The mixture can be ignited
only if the concentration of fuel vapor in the air
is more than about 1% or less than about 6% by
volume. A confined mixture containing more
than 6% fuel vapor becomes a practical
explosion hazard only if it is vented to admit a
greater portion of air.
The significance of flash- and fire-point value
lies in the dissimilarity that exists in the volatility
characteristics of different petroleum liquids.
Even among lubricating oils of comparable
viscoslty, there are appreciable variations In
lies in the dissimilarity that exists in the volatility
characteristics of different petroleum liquids.
Even among lubricating oils of comparable
viscoslty, there are appreciable variations In
volatility, and hence in flash and fire points. In
general, however, the storage and operating
temperatures of lubricating oils are low enough
to preclude any possibility of fire. Among the
exceptions to this situation are such products as
quenching and tempering oils, which come in
direct contact with high temperature metals.
Heat-transfer oils, used for heating or cooling,
may all reach temperatures in the flash- and
fire-point ranges. Similarly, in the evaluation of
roll oils, which are applied in steel mills to hot
metal sheets from the annealing oven, fire haz-
ard may likewise be a consideration. In many of
these cases, however, auto-ignition temperature
is of greater significance. At the auto-ignition
temperature, as determined by test, fire is not
merely a possibility, It actually occurs
spontaneously, i.e., without ignition form any
outside source.
general, however, the storage and operating
temperatures of lubricating oils are low enough
to preclude any possibility of fire. Among the
exceptions to this situation are such products as
quenching and tempering oils, which come in
direct contact with high temperature metals.
Heat-transfer oils, used for heating or cooling,
may all reach temperatures in the flash- and
fire-point ranges. Similarly, in the evaluation of
roll oils, which are applied in steel mills to hot
metal sheets from the annealing oven, fire haz-
ard may likewise be a consideration. In many of
these cases, however, auto-ignition temperature
is of greater significance. At the auto-ignition
temperature, as determined by test, fire is not
merely a possibility, It actually occurs
spontaneously, i.e., without ignition form any
outside source.
Since flash and fire point are also related to
volatility, however, they offer a rough indication
of the tendency of lubricating oils to evaporate
in service. It should be apparent that lower flash
and fire points imply a greater opportunity for
evaporation loss. The relationship between test
results and volatility is by no means conclusive,
however. The comparison is distorted by several
additional factors, the most important of which is
probably the manner in which the oil is
produced.
volatility, however, they offer a rough indication
of the tendency of lubricating oils to evaporate
in service. It should be apparent that lower flash
and fire points imply a greater opportunity for
evaporation loss. The relationship between test
results and volatility is by no means conclusive,
however. The comparison is distorted by several
additional factors, the most important of which is
probably the manner in which the oil is
produced.
The relationship between flash and fire point, on
the one hand, and volatility, on the other, is
further distorted by differences in oil type. For a
given viscosity, a paraffinic oil will exhibit higher
flash and fire points than other types and may
be recognized by these test results. Paraffinicity
may also be indicated by a high viscosity index
or by a high pour point.
the one hand, and volatility, on the other, is
further distorted by differences in oil type. For a
given viscosity, a paraffinic oil will exhibit higher
flash and fire points than other types and may
be recognized by these test results. Paraffinicity
may also be indicated by a high viscosity index
or by a high pour point.
Fire and flash points are perhaps of greater
significance in the evaluation of used oils. If an
oil undergoes a rise in flash or fire point in
service, loss by evaporation is indicated. The
more volatile components have been vaporized,
leaving the less volatile ones behind; so an
increase in viscosity is apparent. An excessive
significance in the evaluation of used oils. If an
oil undergoes a rise in flash or fire point in
service, loss by evaporation is indicated. The
more volatile components have been vaporized,
leaving the less volatile ones behind; so an
increase in viscosity is apparent. An excessive
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