1.1 This standard covers specifications and test methods for unused polybutenes, as delivered, intended for use as insulating liquids in electrical equipment. The requirements given in Sheet 1 are only applicable to unused polybutenes used as an impregnant for paper insulated capacitors and cables and as a filling medium for pipe type cables. Note.- Polybutenes may be used in transformers, but nowadays this application is not wide enough to justify the development of international specifications. Action could be taken when needed. 1.2 For the purpose of this standard two grades of polybutenes are considered: Class I and Class II based on the values of certain physical properties namely: viscosity, flash-point and pour-point.