ASTM D8211-21 Standard Test Method for Hot Surface Ignition Temperature of Gases on a Plane Surface

The standard “ASTM D8211-21 Standard test method for hot surface ignition temperature of gases on a flat surface” published by the American Society for Testing and Materials (ASTM) describes a test method for distinguishing between gases that will or will not ignite when they hit a hot surface when heated to a temperature of 2 degrees plus/minus 800 degrees or greater for a period of 5 minutes.

This test method is applicable to any non-pyrophoric substance that is a gas or liquefied gaseous gas at ambient temperature and pressure, in particular GHS category 1B gases.

This test method should be used subject to the limitations that a single fire hazard property, such as flash point, autoignition temperature or performance under the conditions of the present method, shall not be used to define or assess the fire hazard or fire risk of a material, product, assembly or system under actual fire conditions. Fire hazard properties measured under controlled laboratory conditions may still be used to accurately describe the response of materials, products, assemblies or systems under those controlled conditions. Properties measured under controlled laboratory conditions may be used as elements of a hazard or risk assessment only when such assessments take into account all factors relevant to the evolution of the fire hazard of a particular situation.

This standard is used to provide a quantitative measurement of the realistic surface ignition temperature of a gas or liquefied gas in a non-static environment.

For the purposes of this standard, the following terms and definitions apply:

• Autoignition temperature is the lowest temperature at which a substance will ignite spontaneously in the normal atmosphere without an external ignition source.
• The camera is capable of recording at least 30 frames per second.
• The chimney is a quartz cylinder tube with specific dimensions (length 229 mm plus/minus 10 mm, inner dimension 70 mm plus/minus 5 mm).
• An environmental chamber is a chamber that can provide a draft-free environment during testing and provide ventilation after testing is complete. The chamber must be capable of completely removing the test substance and any possible decomposition products after testing is complete.
• The height of the gap, the height of the chimney above the insulation and the plank should be 4 mm.
• The heating element is a unit that can heat a surface in contact with the planchette to a minimum of 800 degrees plus/minus 5 degrees and a maximum of 1000 degrees.
• Hot surface ignition temperature is the lowest temperature at which a substance will ignite in normal atmosphere when it hits a heated surface.
• Ignition is any visible flame immediately above the planchet, including the length of the chimney, initially or up to 2 minutes after the substance hits the planchet. If no flame is visible within 2 minutes, the test is considered to have failed to ignite at the temperature tested. Any visible flame outside the test chimney shall not be considered to be ignited but shall be retested under the same conditions until definitive ignition or non-ignition is determined.
• The insulation is a non-ceramic insulation board with a minimum density of 0,3665 g ⁄cm3. The insulation board should have a minimum thickness of 8 mm plus/minus 0,5 mm and a hole should be cut in the middle to accommodate the planchette. The planchette should fit tightly into the opening, but also in such a way that all parts of the underside of the planchette are in equal contact with the heating element.
• The lower flammability limit is the minimum concentration in air of a substance that will spread flame in a homogeneous mixture of the substance and air under specified test conditions.
• The planchette is a flat stainless steel conical disk with an upper section diameter of 50,8 mm plus/minus 1,0 mm and a height of 8,0 mm plus/minus 0,5 mm. The lower section diameter is 63,5 mm plus/minus 1,0 mm and a height of 4,7 mm plus/minus 0,5 mm.
• A scale is a method of weighing the amount of substance released onto a hot surface.
• The spray nozzle is a 0,3175 cm stainless steel cylindrical tube with an opening at the release end.

During the test, 5 g of the substance is released from the spray nozzle onto a planchet heated to 800 degrees plus7minus 5 degrees, without external ventilation or fan operation. The environmental chamber containing the test equipment must be motionless, excluding the convection effect of the planchet. Ignitions are observed during the initial surface impact of the substance and for 2 minutes after the substance is released, in case of any ignition after impact.

The autoignition temperature of a gas mixture is the minimum temperature at which a gas mixture will ignite spontaneously without an external ignition source. Autoignition temperature is usually determined using small test vessels open to the atmosphere, where the gas is rapidly injected into the test vessel at atmospheric pressure and heated for a predetermined time, observing whether it ignites or not. Autoignition temperature is generally not directly applicable to real-world conditions. Therefore, a test is needed to determine whether a gas or liquefied gas will ignite when released onto a hot surface in a more free environment.

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