Many of us use Safety Data Sheets (SDS) on a regular basis and most of us have come to the realization that these documents fall far short of providing us the safety information we really need. For example, when working with flammable liquids do you trust the SDS data to provide an accurate Flash Point for the material? Because of the inherent errors in standard flash point measurements…
an allowance of at least 11° BELOW the published flash point should be made in the evaluation of an ignition hazard.
A minimum safety factor of 5° is appropriate for single-component liquids having well-defined flashpoints.
A safety factor of 11° is appropriate for mixed liquids of a less certain composition, such as fuels.
Operations at HIGH ELEVATIONS require an ADDITIONAL SAFETY FACTOR, depending on the elevation. The recommended additional safety factor for every 3300 ft above sea level is 3° for complex fuels, such as diesel fuels, and 2°, for pure liquids, such as toluene and ethanol.
Source: NFPA 77