MIL-PRF-87260B(USAF)
4.5.22.3 Correlation test data requirements.
A correlation study shall be conducted for the conductive material(s) to show the effect of
temperature and humidity on the volume resistance and resistivity using the procedure and
±5°F and relative humidity of 10, 50, and 80 ±5 percent, and material thickness of 1, 4, 8, and
12 inches. In addition, electrical resistivity tests shall be run on 1-inch thick specimens at 140,
60, 32, 10, 0, -15, -25, -30 and -40 ±5°F and all data reported including relative humidity
conditions (if possible). Record all values for resistance, resistivity, temperature, humidity, and
material sample overall dimensions (if other than that per 4.5.4). If the conductive material is
found to vary more than two orders of magnitude as a result of the humidity changes, a
correlation curve or extrapolation factor should be developed for use on all production bun tests
where the test conditions will likely be other than 72 ±5°F and 50 ±5 percent humidity. The
correction will enable the qualifying activity to know the resistivity value at standard laboratory
conditions (72°F and 50 percent relative humidity). A plot of resistivity versus temperature shall
also be generated to demonstrate the material's resistivity properties throughout the anticipated
end use temperature range.
4.5.23 Electrostatic fuel impingement test.
A fuel impingement test shall be conducted on the conductive material to demonstrate its
electrostatic compatibility. The testing shall be done in a small scale rig (55-gallon drum or
equivalent). The basic test requirements to be met include:
a. The test tank shall be filled with the conductive material except for a 1 to 2-inch gap
(ullage) at the nozzle inlet area.
b. Fuel requirements: MIL-DTL-83133 Grade JP-8 having the following electrical
conductivities shall be used for the evaluations: 0 to 10, 50, 100, 200, 500, and 800 cu. The
base fuel should be from the same batch and the conductivity level varied through the use of
static dissipation additives. The approved additives are listed in MIL-DTL-83133. Information
relating to mixing of the additives into fuel can be found in T.O. 42B-1-1.
c. Test temperatures: Fuel test temperatures shall include, but not be limited to, 140, 60,
30, 10, 0, -15, -25, -30 and -40 ±2°F. The test fuel temperature is defined as the starting test
temperature, but is not necessarily the fuel temperature at the test end point.
d. The test tank shall be fitted with a straight 1-inch diameter inlet nozzle. The flow rates
simulated shall be up to 150 gallons per minute (gpm) with an approximate velocity as high as
61 feet per second (fps). The flow rate/velocity shall then be systematically adjusted until the
associated discharge activity appears and/or ceases. The critical flow rate/velocity required for
discharge activity shall be identified and compared to the candidate material's critical flow
rate/velocity for a given standardized fuel. The absence of discharge activity, at the 150 gpm
flow rate, may require the straight inlet nozzle's diameter be reduced to allow higher fuel
velocities. Any changes in the fuel's electrical conductivity shall be noted and recorded. In
addition to discharge activity, charge transfer levels, associated field strength, and induced
voltages on an isolated conductor shall be measured.
e. Baseline fuel impingement tests shall also be conducted on the MIL-DTL-83054 blue
(Type IV or V) using the same batch of fuel that is used on the candidate material. This test
data will be used for comparison to the data for the candidate conductive material.
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