Flammability. generally tests/testing

The flammability of plastics in packaging has to be evaluated using the general test methods for plastics. 

The test gas must be of uniform and known composition. This generally requires on-line gas analysis if flammable mixtures are not supplied from a suitable reservoir. If concentration gradients are created in the surrounding air, errors can be introduced by releasing the test gas stream from a perforated probe doubling as an electrode. The maximum effective energy of a... 

BS EN 61779 Electrical apparatus for the detection of flammable gases. General requirements and test methods ... 

Flashpoint — the lowest temperature of a liquid at whieh it gives off enough vapor to form an ignitable mixture with air near the surfaee of the liquid within the vessel used. Two tests are used—Open Cup and Closed Cup. Generally, the Open Cup method results in flashpoints 5° to 10° higher than the Closed Cup method. Flashpoint < 140°F (Closed Cup) is the eriterion used by EPA to deeide whether a ehemieal is hazardous by ignitability. DOT defines materials with flashpoints of < 100°F as flammable materials, and between 100° and 200°F as eombustible. 

The physical properties important for the projected use of hydraulic fluids are viscosity, density, foaming behavior, and fire resistance. There is no generally recognized test method for measuring flammability of hydraulic fluids, although various test methods maybe utilized (Moller 1989). 

For thermoplastic composites, results of flammability tests are generally reported on the basis of oxygen index values and/or UL-94 ratings (e.g. (11-12). The general problems associated with composites and multicomponent systems have not been addressed in depth and published data pertain primarily to specific glass-filled resins offered by manufacturers, or to composite systems designed to meet the specifications of a particular end use. 

Flash Point — This is defined as the lowest temperature at which vapors above a volatile combustible substance will ignite in air when exposed to a flame. Depending on the test method used, the values given are either Tag Closed Cup (C.C.) (ASTM D56) or Cleveland Open Cup (O.C.) (ASTM 093). The values, along with those given below, provide an indication of the relative flammability of the chemical. In general, the open cup value is about 10° to 15 °F higher than the closed cup value. 

Flame Resistance. Traditionally, small-scale laboratory flammability tests have been used to initially characterize foams (38). However, these do not reflect the performance of such materials in bulk form. Fire characteristics of thermal insulations for building applications are generally reported in the form of qualitative or semiquantitative results from ASTM E84 or similar tunnel tests (39). Similar laiger scale tests are used for aircraft and marine applications. 

From the point of view of the potential for a fire, the closed cup flash point determination is usually the most important. In a perfect closed cup test, the vapor pressure is in equilibrium with the liquid at the temperature of the test. At the flash point, the vapor composition is at the lower flammable limit. In fact, the lower flammable limit can be estimated from vapor pressure data (for a pure compound). Open cup flash points are generally higher and, thus less conservative, than closed cup determinations. The value determined in an open cup test is subject to air movement at the open face of the cup and true vapor-liquid equilibrium probably does not occur. 

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