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® WorleyParsons <br /> resources&energy <br /> 5.6.6.3 Valve Actuators <br /> All control valves will be furnished with pneumatic spring opposed diaphragm actuators <br /> where possible. Pneumatic piston, electric or other actuators can be provided if better <br /> suited for the application or called out on the data sheets. <br /> Valves will be designed to fail in a safe position. <br /> Valve actuators with valve action "fail open" or "fail closed", will be provided with a <br /> mechanical spring or a trip valve and volume tank to fully open or close the valve as <br /> applicable on loss of air pressure. Valve actuators with valve action "fail in place" will be <br /> provided with a mechanism to hold the valve in position on loss of air pressure. Actuators <br /> will be sized sufficiently to achieve the desired "fail" position while the valve is operating <br /> at maximum differential pressure. <br /> 5.6.6.4 Volume Tanks <br /> Volume tanks will be designed to withstand a minimum pressure of 125 psig. <br /> All volume tanks will be constructed in accordance with ASME Boiler and Pressure Vessel <br /> Code, Section VIII, Division 1 (stamped UM). <br /> 5.6.6.5 Sound Control Requirements <br /> For all valves, the equivalent "A" weighted sound level, measured three feet downstream of <br /> the valve outlet and one meter from the un-insulated pipe surface, will not exceed 85 dBA <br /> unless noted otherwise on the valve Data Sheets. Noise reduction will be accomplished by <br /> source treatment, utilizing trim specifically designed for the service. Calculations of noise <br /> will be done in accordance with the International Standard IEC 534-8-3 and submitted with <br /> valve specifications and sizing information. <br /> 5.6.6.6 Positioners <br /> Positioners will be the Fisher DVC6000 Series, electro-pneumatic type utilizing the HART <br /> communication protocol and will be provided with pressure gauges for indicating the air <br /> supply, valve actuator, and control signal pressures. Input signal will be loop powered by <br /> the DCS. Positioners will be designed for a control signal input range of 4-20 mA. <br /> Positioners will provide an output signal from 0 psig to the full supply air pressure to the <br /> valve actuator. Positioners will not be provided with bypasses. <br /> Control valve accessories will be mounted on the valve actuator unless severe vibration is <br /> expected. Control valves with a positioner will not be equipped with a pneumatic valves <br /> unloader. <br /> When valve position feed back is required for DCS information (i.e. non-control use) only, <br /> Fisher digital valve controllers (DVC's) will be utilized to provide a Hart signal back to the <br /> Lodi Energy Center 3.5- 11 LEC AFC <br /> 071608 Rev.A <br />