This document establishes specific functional requirements for injection stations for biomethane into gas transmission and distribution systems operated with gases of the second gas family in accordance with EN 437 in addition to the general functional requirements of prEN 17928-1. This document represents the recommendations at the time of its preparation. This document does not apply to injection stations operating prior to the publication of this document. This document complements prEN 17928-1 by specifying the technical safety requirements to be observed in respect of the chemical and physical properties of biomethane. This document specifies common basic principles for gas infrastructure. Users of this document are expected to be aware that more detailed national standards and/or codes of practice can exist in the CEN member countries. This document is intended to be applied in association with these national standards and/or codes of practice setting out the above-mentioned basic principles. In the event of terms of additional requirements in national legislation/regulation than in this document, CEN/TR 13737 (all parts) illustrates these terms. CEN/TR 13737 (all parts) gives: legislation/regulations applicable in a member state; if appropriate, more restrictive national requirements; a national contact point for the latest information.