Electro-Pneumatic Positioner Series 830/831-WP/EX. Operation & Maintenance Manual

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Mervin Atkinson
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1 Electro-Pneumatic Positioner Series 830/831-WP/EX Operation & Maintenance Manual

2 Electro-Pneumatic Positioner Model 830/831- WP/EXP This operation & maintenance manual corresponds to Forbes Marshall Arca make Electro-Pneumatic Positioner model 830/831. If you experience any difficulty with the installation or operation of this equipment, please contact our Customer Support Manufactured & Marketed by Forbes Marshall Arca Pvt. Ltd. A Forbes Marshall Company A 34/35, H Block, MIDC Estate Pimpri Pune, India TEL. : FAX. :

3 Table Of Contents 1.General 2.Nomenclature/ Model No. 3.Salient Features 4.Specifications 5.Principle Of Operation 6.Block Diagram 7.Installation & Calibration 8.Auto/Manual switch 9. Seat adjuster 10.Maintenance and check 11.Caution and Handling 12.Trouble shooting 13.Positioner With Feedback Transmitter

4 1. GENERAL The electro-pneumatic positioner is used in Control Valves with pneumatically operated actuators. The valve is operated by means of electrical controller or Control Systems With an control signal of 4 to 20 ma or split ranges of 4~12/ 12~20 ma. The 830/831 Electro-Pneumatic Positioner converts this control signal into a pneumatic output in proportion to the lift of the control valve. This manual contains the information required for the installation & usages of this equipment. It is addressed to technically qualified & trained person or having relevant knowledge of instrumentation & control technology. It must be used in the way described in this manual. Successful safe operation of this equipment is dependent upon the proper handling, installation, operation & maintenance. 2.Nomenclature/ Model No W P 83 SERIES POSITIONER 0 - NORMAL 1 - WITH FEEDBACK TRANSMITTER ALWAYS "-" WP - WEATHER PROOF IP66 EX - EXPLOSION PROOF IIB & IIC

5 3. SALIENT FEATURES 1. There is no change in performance in the range of 5-200Hz of Vibrations. 2. Can be Used for Split Range Application 3. Easy to adjust zero and span & calibrate to the required travel of the valve. 4. Easy to convert from ATO (Air to Open) to ATC (Air to Close) action or vice versa. 5. Easy Feedback connection. 6. Fast and accurate response. 7. Low air consumption. 4. SPECIFICATIONS Input Signal Impedance Supply Pressure Air Consumption Air Flow capacity Linearity Hysteresis 4~20 ma DC OHM 1.4~6 kg/cm2 3 lpm at 1.4 bar 80 lpm at 1.4 bar 1% of FS 0.2% of FS Repeatability 0.5% Air Connection Gauge Connection Ambient Temp ¼ NPT (F) 1/8 NPT (F) C to C Protection IP 66 Weight Ex-Proof Elect. Connection 2.8 kg IIB & IIC G1/2 (PF1/2)

6 Electro Pneumatic Positioner 831-WP (With Feedback) Electro Pneumatic Positioner 830-WP Positioner

7 5. PRINCIPLE OF OPERATION This equipment works on the force balance principle and uses a flapper/ nozzle & set of springs to bring the forces under equilibrium at the required valve position with respect to the signal/command given to it. When the input signal from the controller is applied to the torque motor, the armature receives a torque in counter clock wise direction, due to this torque the counter weight/ flapper moves towards left side and the clearance between the Nozzle & the Flapper increases, due to which, the back pressure in the Nozzle decreases. As a result of the above, the exhaust valve of the Pilot Valve moves towards right and the Inlet Valve A opens, thereby the supply air goes to the actuator through port OUT1. The valve Spindle will move up or down depending up on the actuator configuration (ATO/ATC) and the Feedback Spring will lengthen or shortens by the movement of Feedback Lever. When there is a force balance between Feedback Spring tension and the Torque generated by the Torque Motor, the valve Spindle stays in it s position.

8 6. BLOCK DIAGRAM INPUT 4~20 ma SIGNAL MAGNET & COIL ARRANGEMENT FLAPPER & NOZZLE MECHANISM PILOT VALVE STABILIZER /COMPENSATION SPRING ACTUATOR FEEDBACK SPRING FEED BACK LEVER (OUTPUT ) VALVE STROKE 7. INSTALLATION & CALIBRATION a. Check that the Pneumatic pipes/ tubing are properly flushed. b. Connect the wires from the controller, at the terminal block of the positioner. + & - signs are printed at the terminal block of the positioner for the ease of connection. The grounding terminal should also be connected. 6 Positioner Positioner Mounting Bracket Stroke Scanning Lever 3 Threaded Pin 2 Link 1 Lift Indicator Sr. No. Part Name c. Connect the Feedback lever to the Control Valve s Link mounted on the Valve s Lift Indicator. Apply 50% signal ( i.e.12 ma DC) and position the Stroke Scanning Pin/ Positioner in such a way that that the Feedback Lever is at 90 0.

9 d. For best performance the movement of the Feedback Lever should be between +15~20 0 to 15~20 0 from the 90 0 (horizontal position set at 50% signal). Pl. check that, while setting the full stroking angle, the Feedback Lever should not foul with the stoppers, provided near the Feedback Lever Connection point on to the Positioner. e. Position the SPAN lever as per the actuator function i.e. ATO (Air to Open) or ATC (Air to close), as explained under ATC Actuator ATO Actuator ATC ACTUATOR ATO ACTUATOR SPAN Lever Fixing Screw Lock Screw Lock Screw OUT2 OUT2 SUP AIR OUT1 SUP AIR OUT1 SPAN Lever Fixing Screw For changing the position of SPAN Lever, the Lock Screw, should be loosened slightly, to avoid getting the Feedback Spring damaged. After re-orienting the SPAN Lever to the desired position, the Lock Screw should be tightened carefully. While changing the position of SPAN Lever, pl. take care not to stretch the Feedback Spring. OUT2 port is not to be used, unless confirmed from works. f. Apply, starting signal (4 ma) and turn the Zero setting adjuster, to set the zero setting. (Clockwise rotation of the adjusting wheel will increase the pneumatic supply to the actuator, to decrease the supply to actuator rotate the adjuster in CCW direction). g. Then apply 100% signal (20 ma), if the valve is not taking 100% stroke then slightly loosen the Lock Screw mounted on the SPAN Lever, rotate the knob on the SPAN lever to achieve the full stroke position. After setting the SPAN, again check the Zero setting at 4 ma and set if found disturbed. After setting, carefully tighten the Lock Screw of the SPAN Lever. Note - The positioner can be set in Split Range also (i.e. 4~12 ma or 12~20 ma), as described under Split Range 4~12mA Set ZERO at 4mA & SPAN at 12mA for 100% valve travel. Recheck ZERO after setting SPAN, correct, if found disturbed. Split Range 12~20mA - Set ZERO at 12mA & SPAN at 20mA for 100% valve travel. Recheck ZERO after setting SPAN, correct, if found disturbed.

10 8. By-Passing The Positioner/ A-M Screw - The Positioner can be by-passed, by the adjustment of A-M Screw. The factory setting is for AUTO mode, however to by-pass the positioner, rotate the A -M screw in counterclockwise direction slowly towards M marking on the Pilot Valve (Ref. fig. Under Point no.5 In by-pass mode, the full pr. of the supply air goes to the Actuator. Therefore, pl. be careful to check the air supply recommended for the actuator. After using the Positioner in manual mode, again rotate the A-M Screw in Clockwise direction towards A to go into AUTO Mode. It should be fully tightened for AUTO Operation. 9. SEAT ADJUSTOR (Should Not be disturbed) This is set at the factory at fully tight position and should not be disturbed. Disturbing this screw may cause positioner malfunctioning. 10. MAINTENANCE AND CHECK 1. If the quality of the supply air is fouled, then the positioner may not operate normally. Moist air may damage the Pilot Valve/ Torque Motor and cause Positioner to malfunction/ defunct. The requirement for a quality air supply can be found in the instrument society of America s Quality Standard for Instrument Air (ISA-S7.3) or BS 5967:Part 2. Basically, this standard calls for the following Particle Size The maximum particle size in the air stream at the instrument should be no larger than 3 microns. Dew Point - The dew point -at line pressure- should be at least 10 0 C below the minimum temperature to which any part of the instrument air system is exposed at any season of the year. 2. The compressed air cleaning/de -humidifying system should be checked periodically. 3. When the fixed orifice is clogged with carbon particles or others, remove the pilot valve Auto/Manual changeover screw (built-in fixed aperture) and clean it by inserting a 0.2 wire (provided at the inside of the Positioner Cover) into the aperture. If it is required to be replaced with new one, stop the supply pr. and remove the Stopper Screw of the pilot valve. 4. Check the positioner once a year. If any abnormality is observed, contact our works. 5. There should not be any air leakage from the tubing. Use pipe sealant sparingly, only on the male thread of the tube fittings. A non-hardening sealant is strongly recommended.

11 11. CAUTION AND HANDLING 1. Do not apply large vibration or impact to the positioner. it causes trouble the positioner must be handled very carefully during transportation and operation. 2. If the positioner is used under temperature outside of the specifications, the sealing materials may deteriorate quickly and also the positioner may not operate properly. 3. Do not open the terminal cover at a dangerous position (hazardous area) during operation or during power conduction. 4. Be sure that the terminal cover and body cover are put on during the operation. 5. If you leave the positioner at the operation site for a long time without using it, put a polythene cover on it so that the rainwater does not harm it in any way. 6. If the atmosphere is of high temp. Or high humidity, take measures to avoid condensation during shipment. 7. For proper functioning of the positioner, use only factory authorized replacement parts. Substitutions of components can impair the performance of the equipment. 8. When the positioner is installed without safety barriers, switch off electrical power supply at its source before connecting or disconnecting signal/feedback wiring. 12. TROUBLE SHOOTING PROBLEM CAUSE WHAT TO DO Too Low or None Supply Pr. Check Supply Pr. Wrong Wiring of (+ve) & (-ve) Terminals Correct (+ve) & (-ve) No Response when Input Signal is Applied Short or Open Circuit of Torque Motor Clogged Nozzle Loose or Wrong Setting of Feedback Lever Replace Motor Unit Clean The Nozzle with the help of wire provided in the Positioner Cover OR Replace the Motor Unit Correct Setting/ Tighten

12 PROBLEM CAUSE WHAT TO DO Valve Operates Only for 0% & 100% Signal i.e. No Response for in between Signals and Actuator Operates Only to ON or OFF Position OUT PUT Pressure Raised and Stays, Does Not Come Down OUT PUT Pressure is Operated by A/M Switch Only Hunting is Occurring Linearity is not Good Wrong Orientation of SPAN Switch A-M Screw is Disturbed Wrong Connection of OUT1 & OUT2 Ports Leakage of A/M Switch Wrong Orientation of SPAN Switch Clogged Fixed Orifice Clogged Nozzle Disturbed Compensation/ Stabilizer Spring Clogged Fixed Nozzle Wrong Setting of Feed Back Lever Wrong ZERO, SPAN adjustment Supply Pressure is unstable Loose Pneumatic connections in the Actuator or Positioner Correct to the Required Position (Refer Point 8e) Fully tighten the A -M Screw (It has two O- Rings) Correct the Pneumatic Connection w.r.t. the Position of SPAN adjustment Switch (Refer Point 8e). Tighten or Replace O Rings of A/M Switch Correct to the Required Position (Refer Point 8e) Clean the Orifice with the help of Wire, provided in the Positioner Cover Clean The Nozzle with the help of wire provided in the Positioner Cover OR Replace the Motor Unit Correct the Positioning of Stabilizer Spring Clean The Nozzle with the help of wire provided in the Positioner Cover OR Replace the Motor Unit Readjust the setting of the Feed Back Lever (Refer Point 8a & 8b) Readjust the ZERO & SPAN Check the Air Leakage from the Pneumatic supply OR Replace the Air Filter Regulator Check & correct

13 13. POSITION TRANSMITTER (Model No.831-WP/EXP) Electronic position transmitter is designed for sensing mechanical position change of Valve Spindle vis-à-vis signal given to the Positioner. The output is in DC current 4~20 ma. The split range feedback can also be set with the help of ZERO & SPAN setting Technical Data Connection Type Input Signal Output Signal Supply Voltage Load resistance Noise Range 2 Wire Up to 0~45 0 Angular Travel 4-20mA DC VDC Ohm 50mV pp Ambient Temp. -20 o C 60 o C (-4 0 to F) Linearity Hysteresis Sensitivity ± 1% of FS ± 0.5% of FS ± 0.5% of FS 13.2 Wiring Diagram SPAN ZERO ACTUATOR SELECTION SWITCH ATC ATO ATC - Air to Close Actuator ATO - Air to Open Actuator INPUT (4 ~20 ma) OUTPUT 4 ~20 ma (AT 24 VDC) [ Note : Position of Actuator Selection Switch is for ATO Actuator ] 13.3 Adjustment Instruction 1) ZERO Adjustment Clockwise adjustment shall increase the output current. 2) SPAN Adjustment Clockwise adjustment shall increase the output current. After adjusting the SPAN, again check the ZERO setting, if required, adjust it. Note : Adjustment should be done carefully as excessive rotation of the adjustment screw may damage the adjustment POTs.

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