MIL-DTL-24607B
APPENDIX A
RESISTANCE TO IGNITION
A.1. SCOPE
A.1.1 Scope. This procedure determines whether a paint will ignite into flames when the sole ignition source is
the heated metallic substrate to which the paint adheres. This Appendix is a mandatory part of the specification.
The information contained herein is intended for compliance.
A.1.2 Resistance to auto-ignition. The test yields information on the ability of the coating to resist auto
ignition, running and dripping when subjected to a very rapid heat rise and information on the ability of the paint to
resist spread of the flame across the test specimen, as well as the tendency of a paint to ignite secondary flames by
flaming drips.
A.1.3 Test conditions. The conditions of the test have been standardized so that paints passing this test may be
safely used on ships' bulkheads and overheads where non-flaming paints are required to prevent fired from
spreading from one sealed compartment to the next during a severe shipboard fire.
A.2. TEST APPARATUS
A.2.1 Test apparatus. The recommended apparatus consists of a high amperage direct current (DC) generator
capable of 300 to 400 amps, electrodes for holding the specimen, an ammeter attached across an in-line shunt, a
voltmeter, and a switch capable of handling the voltages and currents involved. The wiring diagram is shown on
figure A-1 (found at the end of this Appendix A). The current from the DC generator is shunted directly through the
test specimen to cause rapid heating. 3/0 stranded welding cable is recommended for wiring.
A.2.1.1 Test apparatus location. The test apparatus shall be arranged in a shielded cabinet or room to reduce air
current effects. Air moving past the specimen shall be regulated to that caused only by convection heating of the
test specimen.
A.2.2 Test panels preparation. Test specimens shall be coated to either 0.15 mm dry film thickness in as many
coats as necessary to achieve 0.15 mm, or to that thickness recommended by the manufacturer's data sheet,
whichever is greater. If multiple coats are required to achieve the test thickness, at least 24 hours, but no more than
48 hours shall lapse between coats. Fully coated test specimens shall be aged 14 days before being tested.
A.3. PROCEDURE
A.3.1 Calibration of temperature. Calibration of the 1832 °F (1000 °C) in 60 seconds time temperature
curves for the particular test specimens and power source shall be conducted. The time-temperature curve is
determined by the cross section and resistivity of the actual test specimens used. Temperature-indicating crayons,
temperature-indicating paints, or optical pyrometers are recommended. Thermocouples are not recommended due to
the current flowing in the test specimen.
A.3.2 Test specimen observation. The test specimen shall be observed and the following shall be recorded:
A.3.2.1 Auto ignition. Flaming (ignition) of the paint before reaching 1832 °F (1000 °C).
A.3.2.2 Smoke generation. Fumes or smoke from the paint and the time at which fumes/smoke began.
A.3.2.3 Smoke observation (qualitative). Volume of smoke (light, moderate, or heavy).
A.3.2.4 Performance observations. Other characteristics, such as slouching, dripping, softening, or color
changes.
A.3.2.5 Documentation. Video recording and color slides shall be taken during and after the test, particularly
at the time of ignition and at the point of maximum involvement, and after the completion of the test.
A.3.3 Analysis of test results. Test results shall be in accordance with the requirements of 3.6.13.
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