with the thermometer with indicated readings that fall
within the limits 20°-230°F.
First, you must understand the term FLASH
POINT. Flash point is the LOWEST temperature at
which the fuel gives off a VAPOR that can ignite.
In preparation for use, the flash-point tester (fig. 3-
9) is to be placed on a level, steady surface. If the room
where the tests are to be conducted is drafty, it is good
practice (but not required) to surround the tester on
three sides with a shield about 18 inches wide and 24
inches high. Do not make the shield out of wood or wood
To make the flash-point test, carry out the following
1. As previously mentioned, do not test gasoline
products in this machine. Thoroughly clean and dry all
parts of the cup and its accessories before starting any
Figure 3-9.Flash-point tester and metal shield.
2. Fill the cup with the fuel to be tested up to the
level indicated by the filling mark. Fuel containing free
water is not to be tested since the results you would get
would not be accurate.
3. Place the lid on the cup and set the cup in the
stove. Take special care because the lid has locating
devices so it fits only one way.
4. Insert the thermometer. It is known that JP-5
fuel has a flash point of 140°F, so use the appropriate
thermometer that has the range of 20°-230°F.
5. Light the test flame and adjust it by the valve
screw on the burner block, so the flame has a 5/32-inch
diameterthe same size as the bad provided for
6. Plug in the unit to a 115-volt power supply.
Adjust the supply of heat by adjusting the dial on the
powerstat until the temperature reading increases by
not more than 11°F per minute nor less than 9°F per
7. Connect the stirrer to the stirrer motor.
8. Apply the test flame when the temperature of the
sample is 30° to 50°F below the expected flash point of
the fuel, and thereafter in multiples of 2°F. For example,
if the expected flash point is 140° (JP-5), the test flame
should be applied starting at 90°F, then 92°, 94°, and so
forth. You apply the test flame by operating the knurled
hand knob that controls the shutter and test the flame
burner. The flame is lowered in one-half second, left in
the lowered position for 1 second, and quickly raised to
its high position.
Discontinue stirring during the application
of the test flame.
9. The flash point is the temperature read on the
thermometer at the time of the flash.
The true flash must not be confused with
the bluish halo that sometimes surrounds the
test flame for the applications preceding the one
that causes the actual flash.
The refractometer kit (fig. 3-10) is used to deter-
mine the amount of fuel system icing inhibitor (FSII in
jet fuels. Although it is small and made of plastic,