Preface: This is the first edition of CSA C22.2 No. 60079-40, Explosive atmospheres — Part 40: Requirements for process sealing between flammable process fluids and electrical systems, which is an adoption, with Canadian deviations, of the identically titled IEC (International Electrotechnical Commission) Technical Specification 60079-40 (first edition, 2015-02). It is one in a series of Standards issued by CSA Group under Part II of the Canadian Electrical Code. At the time of publication, IEC TS 60079-40:2015 is available from IEC in English only. CSA Group will publish the French version when it becomes available from IEC. This Standard is intended to be used in conjunction with CSA C22.2 No. 60079-0, Explosive atmospheres — Part 0: Equipment — General requirements. This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. Scope: This document provides specific requirements for process sealing between a flammable process fluid and an electrical system where a failure could allow the migration of the process fluid directly into the premises wiring system. NOTE Some definitions differentiate the terms "flammable" and "combustible" liquids on the basis of their flashpoints. Combustible liquids under conditions of elevated pressure and/or emperature can lead to the formation of flammable mists and aerosols which are within the scope of this technical specification. This document contains requirements for evaluation, construction and testing of single process seal equipment, dual process seal equipment, and add-on secondary process seals. The requirements of this document do not apply to conduit sealing devices, cable glands and other wiring sealing methods addressed in the IEC 60079 series or other standards. Requirements for basic electrical safety and explosion protection are not addressed by this document, but may apply to the equipment under investigation. The effects of leakage to the environment are not addressed by this document.