DIN 33821:2009-03

This standard applies to requirements and examinations of safety relief valfes and pressure relief valves, together called safety relief valfes (SBV), in gas supply systems with operating pressures up to 100 bar operated with gases according to DVGW G 260 with the following demarcations: - Operating temperature -20 °C to +60 °C; - Nominal sizes up to DN 200. This standard applies to directly and indirectly working safety blow-down valves, which open with the exceeding of the adjusted pressure and close automatically again, if the pressure which is supervised is sufficiently low. This document considures the following classes of safety relief valves: - Class A: Safety relief valves as a 'safety accessory' according to Article 1 of Directiv 97/23/EC (PED); - Class B: Pressure relief valves as 'pressure accessory' (without the safety function) in accordance with Article 1 of Directive 97/23/EC (PED). This standard applies also to safety relief valves which are integrated in or combined with gas pressure regulators. This standard does not apply to safety relief valves which lock in the open position, and to bursting discs. For input pressure or differential pressure controlling pressure regulators DIN EN 334 should be applied analogously.