The hydraulic accumulators shall be of piston type, nitrogen charged, and mounted in vertical position. All accumulators shall be equipped with a directly mounted local piston position indicator of permanent magnet type. The upper and lower piston position limits, where proper function of the whole system is verified, shall be marked clearly on the accumulator/indicator.All equipment shall comply with the requirements of the specific hazardous area in which they will be installed.This specification excludes requirements for the following actuator locations: e Non-conventional pressure protection systems (TR1956). Surface Wellhead and Christmas Tree System (TR3540). Subsea Wellhead, Tree and Completion/Workover Equipment (TR3541). Large Valvesin Pipeline Transportation Systems (TR1236). Control & Choke Valves (TR2212). The minimum requirementsherein arestill applicable for the above excluded systemsif the actuated valve is given an additional safety function to its original function in the processplant.Typical response times that shall be complied with unless other requirements are specified: � Time from activation to start execution, e.g. de-energized solenoid valve, shall be less than 2 seconds. � PSD/ESD valve travel time (in service) at minimum operating hydraulic/pneumatic supply pressure shall not exceed 1 sec/inch (valve size), or maximum 45 seconds to reach safe state. For valves 8 inch or less, a typical travel time may be set to 8 seconds. Travelling speed when travelling from the predefined safe position shall be agreed between buyer and supplier.All welding shall be continuous and welding of stressed components shall be full penetration welds. When welding is applied onto components specified as 316 SS material, the material grade shall be AISI 316L.External nitrogen bottles, of standard size and material, according to design code BS 5045 Part 1, shall be included where applicable. The accumulator's nitrogen system shall be equipped with an easily operable nitrogen pre-charging arrangement. All valves in this service shall be of the soft seated type.For all accumulators pre-charge graphs shall be made showing the pre-charge pressure of nitrogen under different ambient temperatures. The graph shall cover the specified operating temperature range in steps of 5 0 C. The graphs shall be a part of “Sizing and calculations” and a copy shall also be enclosed with the accumulators at delivery.For small industrial standard pressure vessels with design pressure (PS, bar) less than 10 bar g and having a product of PS and V (volume, litre) less than 25 for gas and 200 for liquids, and having an approved type examination according to PED, any of the referred codes may be used without additional requirements.ATEX – Directive 94/9/EC For electrical equipment (e.g. electrical actuators and control circuits) conformance to the Directive shall be issued by a Notified Body in accordance with 94/9/EC Annex III. However, for hydraulic actuators, pneumatic actuators and assembled units (e.g. actuated valves) the manufacturer can affix the CE marking and draw up a written declaration of conformity according to Annex VIII of the Directive. As stated in ATEX Guidelines section 5.2.1 the Directive is not applicable for pressure relief valves and hand operated valves.The drive from the motor to the valve shall be through a gearbox which incorporates a clutch mechanism to allow manual operation of the valve via a handwheel. A local, mechanical valve position indicator shall be provided within the actuator body. The clutch mechanism shall be key lockable in hand or auto position.G.7 Surface protection All surface protection shall be according to NORSOK M-501 System 1.