ASTM F2676-09

This test method determines the effectiveness of arc protective blankets in suprressing the combined effects of an arc flash and arc blast.

The arc exposure energy is produced from controlled phase-to-ground arc fault. The resulting arc flash and blast energy are intentionally directed onto the test specimen to simulate worst case conditions.

Test results will describe the maximum arc current and product of arc current and cycles at which test specimens block the energy without breakopen, ability to self-extinguish afterflaming, afterflame time and the detection of mechanical attachment failures during testing. Mechanical attachment failure and afterflame time are obtained from visual observations and video recording after each arc exposure.

This test method maintains the arc protective blanket in a vertical position and does not involve movement except that resulting from the arc exposure.

In this test method, test specimens are exposed at three arc current levels to determine the test specimen’s performance.

Note 2—In experimental testing, some blankets increase in protection (in value of kA*cycles to cause breakopen) as the arc current increases and some decrease as shown in Fig. 1. This test method is designed to recognize this behavior and to specify testing over the range of arc current levels including lower levels of 5 kA or 10 kA, or both.

This test method specifies a standard set of exposure conditions. Different exposure conditions may produce different results.

Note 3—In addition to the standard set of exposure conditions, it is permitted to test using other conditions representative of the expected hazard, reported all non-standard test conditions that are used.

FIG. 1 Example of Performance Trend for Different Blankets

1.1 This test method is used to evaluate the ability of the arc protective blankets to withstand the effects of arc flash and arc blast in a configuration in which the blanket is hung or anchored near energized equipment. Specifically, this test method is used to determine the arc protective blanket’s (1) resistance to breakopen, (2) mechanical strength, and (3) ability to self-extinguish flames following a controlled arc exposure.

1.2 This method is used to determine the performance of arc protective blankets in terms of: maximum arc current level expressed in kA and BTP (BTP) expressed as the product of arc current in kA and arc duration in number of cycles to cause breakopen (kA*cycles). Cycles are on the basis of 60 Hz.

1.3 Blanket test specimens used in this test method are test size blankets of 152 ± 5 cm (60 ± 2 in.) by 122 ± 5 cm (48 ± 2 in.). The test specimen size is for testing purposes only. Commercially available arc protective blankets either larger or smaller than the test specimen size are covered by this standard.

1.4 The arc protective blankets described in this test method are made of flame-resistant materials and are available in varying sizes and configurations based on the application.

1.5 This test method shall be used to measure and describe the properties of materials, products, or assemblies in response to incident thermal (convective and radiant) and pressure energies generated by an electric arc under controlled laboratory conditions.

1.6 The values stated in SI units shall be regarded as standard. The values given in parentheses are mathematical conversion to inch-pound or other units commonly used for arc testing.

1.7 This standard shall not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. However, results of this test may be used as elements of a fire assessment, which takes into account all of the factors, which are pertinent to an assessment of the fire hazard of a particular end use.

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautions, see Section 7.