A Long Experience in Energy Equipment and one Goal: The Customer s Satisfaction. Pneumatic Diaphragm Actuator. PDA series

Transcription

1 A Long Experience in Energy Equipment and one Goal: The Customer s Satisfaction. Pneumatic Diaphragm Actuator PDA series

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3 CONSTRUCTIONAL DETAILS Diaphragm case and internal plate This is in high quality pressed steel of compact structure, especially prepared far maximum strength. The actuator stem is screwed on to the internal plate and buttwelded in the direct actuator; the actuator stem is actuator; the actuator stem is mechanically locked by means of a nut and a safety washer to prevent loosening with reverse actuator. Yoke This is constructed in one piece and is bolted to the diaphragm case. If is fixed against the bonnet by means of a threaded ring nut. Materials can be carbon steel (standard) or treated alloy steel for low ambient temperatures. Spring The spring, constructed in silicon-manganese steel, is phosphated or painted «black japan» against corrosion and has fiat parallel ends. Direct actuator The air pressure 3-15 psi or 6-30 psi enters the top diaphragm chamber. The increase in air pressure operates against the diaphragm, compressing the spring with corresponding movement of the actuating stem; with a decrease in pressure the spring returns backwards together with the actuator stem. The actions air to open"(stem pushed down opens) and air to dose (stem pushed down closes) are obtained using a direct actuator for the valves with an invertible body. For valves with a non invertible body, air to open action is obtained using a reverse actuator. Reverse actuator The reverse actuator is used when "air to open» action is required for a valve with a non-invertible body. The air pressure of 3-15 psi or 6-30 psi enters the lower diaphragm chamber. The increase in air pressure forces the stem up, decrease in air pressure the spring returns backwards together with the actuator stem. The construction is similar to that of the direct actuator except that the reaction spring which is compressed upward by means of a spring cap integral with the stem and by means of the adjusting screw and has a sealing 0-ring around the stem in order to seal the lower chamber. Adjusting screw In hardened 42CrMo4 stainless steel, its purpose is to regulate the initial thrust pressure of the spring so that the valve stem begins its stroke as the pressure on the diaphragm is equal to 3 or 6 psi for standard ranges 3-15 or 6-30psi respectively. It is also provided with a stem guide to ensure perfect alignment with the plug stem. Actuator stem This is constructed in AISI304 Plug stem, actuator stem connection The plug stem is screwed into the actuator stem and is locked by means of lock-nuts to prevent turning during operation. For sizes above 2 ½ the lower part of the actuator stem is conical with longitudinal notching for security. Travel indicator A travel indicator in stainless steel, fitted to the valve stem, shows the plug lift on a graduated plate, affixed to the yoke. 2

4 PDA SERIES PNEUMATIC ACTUATOR PDA24L PDA24 PDA18L & PDA18 PDA15 & PDA13 PDA11 & PDA9 3

5 DIRECT ACTION DESIGNATION CODE PDA xxx y D = for DIRECT ACTION I = for REVERSE ACTION MODEL NUMBER 11, 13, 18, 18L, 24 PDA xxx y + HW PDA actuator with Handwheel REVERSE ACTION 4

6 ACTUATOR MODEL TRAVEL SPRING RANGE EFFECTIVE AREA N/psi PDA cm PDA11 (1) cm PDA13 (2) cm PDA15 (3) cm PDA PDA18L cm PDA cm PDA24L cm Notes (1) also available with the same effective area of PDA13, in order to reach a greater thrust (2) also available with the same effective area of PDA15, in order to reach a greater thrust (3) also available with the same effective area of PDA18, in order to reach a greater thrust 5

7 WEIGHT AND DIMENSIONS 6

8 A Long Experience in Energy Equipment and one Goal: The Customer s Satisfaction. VALVITALIA S.p.A. Headquarter: Via Tortona, Rivanazzano (PV) Italy Ph: Fax: info@valvitalia.com Legnano (MI) Office VALVITALIA S.p.A. CONTROL VALVES DIVISION Via Saronnese, Legnano (MI) Italy Ph: Fax: info.systems@valvitalia.com Padova Plant VALVITALIA S.p.A. - SYSTEMS DIVISION Via Campolongo, Due Carrare (PD) Italy Ph: Fax: info.systems@valvitalia.com Vicenza Plant VALVITALIA S.p.A. - VITAS DIVISION VITAS Plant: Via Soastene, Brendola (VI) VITAS Offices: Via Olmo, 31/ Altavilla Vicentina (VI) Italy Ph: Fax: info.vitas@valvitalia.com Piacenza Plant TECNOFORGE S.p.A. Via Emilia Pavese, CastelSanGiovanni (PC) Italy Ph: Fax: tecfor@tecfor.it Internet: Arena Plant TECNOFORGE S.p.A. Via Stazione, Arena Po (PV) Italy Ph: Fax: tecfor@tecfor.it Internet: China Plant VALVITALIA CHINA VALVES CO.LTD. (Suzhou) Wujiang Econimic Development Zone - Jiangshu Province - China Ph: Fax: info.china@valvitalia.com Rev.1.4 7