Flammability testing described

The UL flammability ratings describe the relative ease of ignition and combustibiUty of plastics. Tests include the measurement of flame propagation, time to self-extinguish, melt and drip with and without flame, and oxygen indexes. Some engineering plastics, eg, polyetherimides, are, as ranked by this test, inherently nonflammable. Others can be made nonflammable by compounding with flame retardants (ERs) such as bromine... 

Inflammability of Explosives Tests (Flammability Tests). See also Index of Inflammability in Vol 1, p XVII. These tests are designed to ascertain the behavior of explosives towards open flame. The following tests are described by Reilly (Ref 1) ... 

There are literally hundreds of test methods to evaluate material flammability and this chapter can only scratch the surface. The intent was to identify and describe the different aspects of material flammability and to illustrate how they can be measured. Several commonly used flammability tests not covered in this chapter are described elsewhere in the book. For example, Chapter 24 addresses flammability testing of textiles. The reader is referred to the end of this chapter for a short list of more comprehensive surveys of flammability tests. 

ISO 871 [1IJ details a determination of ignition temperature using a hot-air furnace. This test determines the temperature at which plastics begin to decompose to flammable gaseous products. The original (1968) version of this test has recently been replaced by a version of the Setchkin test described immediately below. 

A series of flammability tests and guidance for their use when applied to electrical components is given in the lEC 695 2 scries of tests (individually referenced below). However they include a number of different ignition sources which could be applied to many plastics materials, since these arc frequently used by the electrical industry. These standards are similar to those described above but are important because each standard... 

This grouping of flammability tests of plastics in the electrics industry is considered in the following discussion. Besides the procedures reported in the lEC Publications, other commonly used or internationally accepted methods are described. 

A bomb calorimetric method is used to measure calorific potential of materials. Similar tests are described in DIN 51900, NF M03-005 and in Italian regulations. This type of test is often used in conjunction with flammability test methods to determine classifications of materials for legislation (for example, in French Building Regulations, only materials with a calorific value of less than 2500 kj kg , as determined in NF M03-005, can be considered for MO, the highest classification). 

The aforementioned definitions imply that flammabihty tests are concerned with a lower level of performance. Passing a flammability tests does not mean that a material will be less hazardous when involved in a fire. This is consistent with one definition of the term flammable, which in ASTM E176, Terminology of Fire Standards, is described as, subject to easy ignition and rapid flaming combustion (25). 

The flammability properties described earher show the potential in specific segments of the apparel market. PLA fabrics with no flame retardant treatments have passed the US tests 16 CFR1610, and have also achieved the standards specific for children s sleepwear, 16 CFR 1615 and 16 CFR 1616. 

Tables 16 and 17 Hst tke analytical test methods for different properties of interest. The Manufacturing Chemists Association, Inc. (MCA) has pubUshed the Chemical Safety Data Sheet SD 63, which describes in detail procedures for safe handling of use of toluene (46). The Interstate Commerce Commission classifies toluene as a flammable Hquid. Accordingly, it must be packaged in authorized containers, and shipping must comply with ICC regulations. Properties related to safe handling are autoignition temperature, 536°C explosive limits, 1.27—7.0 vol % in air and flash point 4.4°C, closed cup.

For many years the usual procedure in plant design was to identify the hazards, by one of the systematic techniques described later or by waiting until an accident occurred, and then add on protec tive equipment to control future accidents or protect people from their consequences. This protective equipment is often complex and expensive and requires regular testing and maintenance. It often interferes with the smooth operation of the plant and is sometimes bypassed. Gradually the industry came to resize that, whenever possible, one should design user-friendly plants which can withstand human error and equipment failure without serious effects on safety (and output and emciency). When we handle flammable, explosive, toxic, or corrosive materials we can tolerate only very low failure rates, of people and equipment—rates which it may be impossible or impracticable to achieve consistently for long periods of time. 

C, except a liquid which when tested at 55°C in the manner described in Schedule 2 to the Highly Flammable Liquids and Liquefied Petroleum Gases Regulations 1972 does not support combustion. 

Flammability. The fire hazard associated with plastics has always been difficult to assess and numerous tests have been devised which attempt to grade materials as regards flammability by standard small scale methods under controlled but necessarily artificial conditions. Descriptions of plastics as selfextinguishing, slow burning, fire retardant etc. have been employed to describe their behaviour under such standard test conditions, but could never be regarded as predictions of the performance of the material in real fire situations, the nature and scale of which can vary so much. 

Schampel and Steen (1975) describe experimental equipment and tests carried out at the Physikalisch-Technische Bundesanstalt (PTB) in Germany on high velocity vent valves. Also, conditions for a sufficient air entrainment and dilution of the vented flammable vapors are discussed. 

When tested in accordance with the procedure described in Appendix B, the odor of the gas shall be distinctive and unpleasant, and the odor in a gas/air mixture shall be such that it is detectable down to a concentration of 20 per cent of the concentration corresponding to the lower limit of flammability for the hydrocarbon mixture concerned. 

Underwriters Laboratories (UL) Test 94 can be used. The placement of the specimen, the size of the flame, and its position and location with respect to the specimen are described in detail in this important UL specifications. Depending on their nonburning to burning capabilities, results of tests are reported as being materials classed 94V-0, 94V-1, 94V-2, 94-5V, etc. (Chapter 2, HIGH TEMPERATURE, Flammability). 

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