This document specifies constructional, functional, testing and marking requirements, sizing and documentation of gas pressure regulators used in the pressure regulating stations in accordance with EN 12186 or EN 12279: for inlet pressures up to 100 bar and nominal diameters up to DN 400; for an operating temperature range from -20 °C to +60 °C, which operate with fuel gases of the 1st and 2nd family in accordance with EN 437 in transmission and distribution networks and also in commercial and industrial installations. "Gas pressure regulators" hereafter will be called "regulators" except in the titles. For standard regulators when used in pressure regulating stations complying with EN 12186 or EN 12279, Annex ZA lists all applicable Essential Requirements except the external corrosion resistance in case of environmental conditions where corrosion is likely to occur. This document considers the following classes/types of regulators: class 1: operating temperature range from -10 °C to 60 °C; class 2: operating temperature range from -20 °C to 60 °C; type IS: (integral strength type); type DS: (differential strength type). This document applies to regulators which use the pipeline gas as a source of control energy unassisted by any external power source. The regulator may incorporate a creep (venting) relief device, complying with the requirements in Annex F. The regulators complying with the requirements of this document may be declared as "in compliance with EN 334" and bear the marking "EN 334". This document does not apply to: regulators upstream from/on/in domestic gas-consuming appliances which are installed downstream of domestic gas meters; regulators incorporated into pressure-regulating devices used in service lines with volumetric flow rate 200 m3/h at normal conditions and inlet pressure 5 bar; regulators for which a specific document exists (e. g. EN 88, etc.); industrial process control valves in accordance with EN 1349.