emerges from the “bath” and the open end is directed into a measuring cylinder. For
the lower-boiling-range samples (i.e., naphthas), this cylinder is placed in a cold
water (slightly below room temperature) bath. The Engler flask rests on an asbestos
or similar plate (F) which has a hole 1
00 in diameter exposing the bottom of the flask
to the heat source. In this case the heat source is shown as a Bunsen burner (C).
A thermometer is introduced into the top of the flask and is positioned so that the
bulb is directly in line with the vapor offtake. The condenser bath is filled with
water and ice and allowed to reach 32
F before heat is applied to the sample flask
and the test begun. The temperature of the sample is increased slowly until the
liquid begins to boil. The initial boiling point is read as the temperature measured
by the thermometer located in the flask when the first condensate drop enters the
receiving cylinder (D) at the end of the condensate bath (B). For low-boiling-point
samples (i.e., naphthas), this receiver is cooled in a water bath (E). For kerosenes,
the water bath (E) is not required. The test is allowed to proceed at a constant rate
and temperature readings are taken at predetermined recovery levels of condensate
(usually, these temperatures will be at 10 vol% recovered and 30, 50, and 90 vol%
recovered). When the flask (A) has been boiled apparently dry, the temperature
shown by the thermometer will rise sharply and then begin to fall. The highest
temperature observed in this rise and fall is the final boiling point of the sample.
Flash Point Test Method
There are two methods used for determining the flash point of intermediate and
finished petroleum products. These are the ASTM D56, the Tag closed-cup method
(commonly known as the Abel flash point), and the ASTM D93, the
Pensky–Martens closed-cup method. The D56 method is used for a material
which has a flash point of between 68
F and 148
F, while the D93 method is
used for all other distillates and residuum products with flash points above 148
F.
Based on this premise, the D56 is used almost exclusively for the kerosene-cutrange materials. Only the Pensky–Martens D93 will be described here.
ASTM D93
A brass test cup is filled to an inside mark with the test specimen. A cover is fitted of
specified dimensions; see Fig. 2. The specimen is heated and stirred at specified
rates. An ignition source in the form of a small flame is directed into the cup at
regular intervals. When the specimen is seen to flash, the temperature of the
specimen is noted as the flash point of the sample.
Significance and Use
The flash point is a measure of the tendency of the material to form a flammable
mixture with air under controlled laboratory conditions. It is however only one of
several properties that must be considered in assessing the overall flammable
hazard of the material. The flash point is used to establish the flammable criteria
in transporting the material. Generally, shipping and safety regulations will be
664
D.S.J. Jones
the lower-boiling-range samples (i.e., naphthas), this cylinder is placed in a cold
water (slightly below room temperature) bath. The Engler flask rests on an asbestos
or similar plate (F) which has a hole 1
00 in diameter exposing the bottom of the flask
to the heat source. In this case the heat source is shown as a Bunsen burner (C).
A thermometer is introduced into the top of the flask and is positioned so that the
bulb is directly in line with the vapor offtake. The condenser bath is filled with
water and ice and allowed to reach 32
F before heat is applied to the sample flask
and the test begun. The temperature of the sample is increased slowly until the
liquid begins to boil. The initial boiling point is read as the temperature measured
by the thermometer located in the flask when the first condensate drop enters the
receiving cylinder (D) at the end of the condensate bath (B). For low-boiling-point
samples (i.e., naphthas), this receiver is cooled in a water bath (E). For kerosenes,
the water bath (E) is not required. The test is allowed to proceed at a constant rate
and temperature readings are taken at predetermined recovery levels of condensate
(usually, these temperatures will be at 10 vol% recovered and 30, 50, and 90 vol%
recovered). When the flask (A) has been boiled apparently dry, the temperature
shown by the thermometer will rise sharply and then begin to fall. The highest
temperature observed in this rise and fall is the final boiling point of the sample.
Flash Point Test Method
There are two methods used for determining the flash point of intermediate and
finished petroleum products. These are the ASTM D56, the Tag closed-cup method
(commonly known as the Abel flash point), and the ASTM D93, the
Pensky–Martens closed-cup method. The D56 method is used for a material
which has a flash point of between 68
F and 148
F, while the D93 method is
used for all other distillates and residuum products with flash points above 148
F.
Based on this premise, the D56 is used almost exclusively for the kerosene-cutrange materials. Only the Pensky–Martens D93 will be described here.
ASTM D93
A brass test cup is filled to an inside mark with the test specimen. A cover is fitted of
specified dimensions; see Fig. 2. The specimen is heated and stirred at specified
rates. An ignition source in the form of a small flame is directed into the cup at
regular intervals. When the specimen is seen to flash, the temperature of the
specimen is noted as the flash point of the sample.
Significance and Use
The flash point is a measure of the tendency of the material to form a flammable
mixture with air under controlled laboratory conditions. It is however only one of
several properties that must be considered in assessing the overall flammable
hazard of the material. The flash point is used to establish the flammable criteria
in transporting the material. Generally, shipping and safety regulations will be
664
D.S.J. Jones