User Guide to Thresholds and Classification - Environmental ...

47User Guide for Thresholds and ClassificationsA suitable method for calculating the flashpoint of mixtures containing both volatile, flammable componentsand non-volatile components (for example, polymers or additives) is that described by Gmehling andRasmussen (1982). The basis of this approach is that the non-volatile components only slightly decrease thepartial pressure of the solvents and thus, the flashpoint of the mixture can be calculated from the measuredflashpoints of the flammable volatile components. The criteria used are as follows.The flashpoint of mixtures need not be determined experimentally if the calculated flashpoint of the mixture isat least 5°C greater than the threshold value (93°C) and provided the:composition of the mixture is accurately known;flashpoint (closed cup) of each flammable component is known;activity coefficient is known for each component as present in the mixture including the temperaturedependence; andliquid phase is homogeneous.Correlation with Dangerous Goods Act 1974 classesThe HSNO Act categories 3A and 3B combined (corresponding to UN class 3 PGs I and II, respectively)match Dangerous Goods Act 1974 class 3(a).The HSNO Act category 3C (UN class 3 PG III) equates to Dangerous Goods Act 1974 class 3(b).The HSNO Act category 3D is a new category into which Dangerous Goods Act 1974 class 3(c), fuel oils, islargely included.Example substancesCategory A substances include:carbon disulphide (UN 1131);diethyl ether (UN 1155); andacetaldehyde (UN 1089).Category B substances include:acetone (UN 1090);ethyl acetate (UN 1173);petrol (UN 1203); andethanol (UN 1170).Category C substances include:amyl acetate (UN 1104);ethylene glycol monoethyl ether (UN 1171); andkerosene (UN 1223).Category D substances include:n-methyl pyrrolidinone;dipropylene glycol monomethyl ether;January 2012 EPA0109