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Pneumatic PositionerSeries 820-PP

Operation & Maintenance Manual

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Pneumatic Positioner Model 820- PPThis operation & maintenance manual corresponds to ForbesMarshall Arca make Pneumatic Positioner model 820-PP.

If you experience any difficulty with the installation or operationof this equipment, please contact our Customer Support

Manufactured & Marketed byForbes Marshall Arca Pvt. Ltd.A Forbes Marshall CompanyA 34/35, H Block, MIDC EstatePimpri - 411018

Pune, India

TEL. : +912027442020FAX. : +022027442040

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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

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1. GENERAL

The pneumatic positioner is used in Control Valves with pneumatically operated actuators.The valve is operated by means of electrical controller or Control Systems (through I/Pconverter) with a control signal of 0.2~1.0 bar or split ranges of 0.2~0.6 bar & 0.6~1.0 bar.

The 820-PP Pneumatic Positioner converts this control signal into a pneumatic output inproportion to the lift of the control valve.

This manual contains the information required for the installation & usages of thisequipment. It is addressed to technically qualified & trained person or having relevantknowledge of instrumentation & control technology.

It must be used in the way described in this manual. Successful safe operation of thisequipment is dependent upon the proper handling, installation, operation & maintenance.

2.Nomenclature/ Model No.

8 2 0 - PP

82 SERIES POSITIONER

0 - NORMAL

ALWAYS "-"

PP - PNEUMATIC TO PNEUMATIC

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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 0.2~1.0 barg (or SPLIT RANGE)

Supply Pressure 1.4~6 kg/cm2

Air Consumption 3 lpm at 1.4 bar

Air Flow capacity 80 lpm at 1.4 bar

Linearity 1% of FS

Hysteresis 0.2% of FS

Repeatability 0.5%

Air Connection NPT (F)

Gauge Connection 1/8 NPT (F)

Ambient Temp -20 0C to +80 0C

Protection IP 66

Weight 2.1 kg

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Pneumatic Positioner820-PP

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5. PRINCIPLE OF OPERATION

T h i s e q u i p m e n t w o r k s o n t h e f o r c e b a l a n c e p r i n c i p l e a n d u s e s a f l a p p e r / n o z z l e & s e t o f s p r i n gs t o b r i n g t h e f o r c e s u n d e r e q u i l i b r i u m a t t h er e q u i r e d v a l v e p o s i t i o n w i t h r e s p e c t t o t h e s i g n a l / c o m m a n d g i v e n t o i t .

W he n the i npu t s igna l f r om the c on t r o l l e r i s a pp l i e d , t h i s p r e s su r e ma ke sbe l low to e xpa nd the r e by e xe r t i ng f o r c e o n f l a pp e r t o move a w a y f r om then o z z l e . T h e c l e a r a n c e b e t w e e n t h e N o z z l e & t h e F l a p p e r i n c r e a s e s , d ue t ow h i c h , t h e b a c k p r e s s u r e i n t h e N o z z l e d e c r e a s e s .

A s a r e su l t o f t he a bove , t he e xha us t va lv e o f t he P i lo t Va lve mov e stow a r ds r i g h t a nd the I n l e t Va lve A op e n s , t he r e b y th e su pp ly a i r goe s t othe a c tu a to r t h r ough po r t O U T 1 . T h e v a lve S p ind le w i l l mo ve up o r d o w nd e p e n d i n g u p o n t h e a c t u a t o r c o n f i g u r a t i o n ( AT O / AT C ) a n d t h e F e e d b a c kS p r i n g w i l l l e n g t h e n o r s h o r t e n s b y t h e m o v e m e n t o f F e e d b a c k L e v e r.

W he n the r e i s a f o r c e ba l a nc e be tw e e n F e e db a c k S p r ing t e n s io n a nd th em o m e n t g e n e r a t e d b y b e l l o w, t h e v a l v e S p i n d l e s t a y s i n i t s p o s i t i o n .

W h e n t h e s i g n a l p r e s s u r e d e c r e a s e s t h e o p e r a t i o n i s r e v e r s e d .

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6. BLOCK DIAGRAM

7. INSTALLATION & CALIBRATION

a. Check that the Pneumatic pipes/ tubing are properly flushed.

b. Connect the pneumatic connections as per the diagram of point 7-e.

c. Connect the Feedback lever to the Control Valves Link mounted on the Valves Lift Indicator.Apply 50% signal ( i.e. 0.6 barg) and position the Stroke Scanning Pin/ Positioner in such a way thatthat the Feedback Lever is at 90 0.

6 Positioner

5PositionerMounting Bracket

4Stroke ScanningLever

3 Threaded Pin

2 Link

1 Lift Indicator

Sr.No. Part Name

1 2 3 4 5 6

INPUTSIGNAL

(0.2~1.0bar

BELLOWCHAMBER

FLAPPER &NOZZLE

MECHANISM

PILOTVALVE

ACTUATOR

(OUTPUT )VALVE

STROKE

STABILIZER /COMPENSATION

SPRING

FEED BACKLEVER

FEEDBACKSPRING

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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 strokingangle, the Feedback Lever should not foul with the stoppers, provided near the Feedback LeverConnection 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

O U T 1

SUP

O U T 2

ATC ACTUATOR

AIR

SPAN Lever Fixing Screw

Lock Screw

SIGNALAIR

O U T 1

ATO ACTUATOR

SPAN Lever Fixing Screw

Lock Screw

SUP

O U T 2

AIR

SIGNALAIR

For changing the position of SPAN Lever, the Lock Screw, should be loosened slightly, to avoidgetting the Feedback Spring damaged. After re-orienting the SPAN Lever to the desired position, theLock Screw should be tightened carefully. While changing the position of SPAN Lever, take care notto stretch the Feedback Spring.

OUT2 port is not to be used, unless confirmed from works.

f. Apply, starting signal (0.2 barg) and turn the Zero setting adjuster, to set the zero setting. (Clockwiserotation of the adjusting wheel will increase the pneumatic supply to the actuator, to decrease thesupply to actuator rotate the adjuster in CCW direction).

g. Then apply 100% signal (1.0 barg), if the valve is not taking 100% stroke then slightly loosen theLock Screw mounted on the SPAN Lever, rotate the knob on the SPAN lever to achieve the fullstroke position. After setting the SPAN, again check the Zero setting at 0.2 barg and set if founddisturbed. After setting, carefully tighten the Lock Screw of the SPAN Lever.

Note - The positioner can be set in Split Range also (i.e 0.2~0.6 barg or 0.6~1.0 barg), as described under

Split Range 0.2~0.6 barg Set ZERO at 0.2 barg & SPAN at 0.6 barg for 100% valve travel. Recheck ZERO after setting SPAN, correct, if found disturbed.

Split Range 0.6~1.0 barg - Set ZERO at 0.6 barg & SPAN at 1.0 barg for 100% valve travel. Recheck ZERO after setting SPAN, correct, if found disturbed.

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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 forAUTO mode, however to by-pass the positioner, rotate the A -M screw in counterclockwisedirection 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 rotatethe A-M Screw in Clockwise direction towards A to go into AUTO Mode. It should be fullytightened 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 maycause positioner malfunctioning.

10. MAINTENANCE AND CHECK

1. If the quality of the supply air is fouled, then the positioner may not operate normally. Moist airmay 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 AmericasQuality Standard for Instrument Air (ISA-S7.3) or BS 5967:Part 2. Basically, this standardcalls 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 0C below the minimumtemperature to which any part of the instrument air system is exposed at anyseason 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 valveAuto/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 replacedwith 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 themale thread of the tube fittings. A non-hardening sealant is strongly recommended.

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11. CAUTION AND HANDLING

1. Do not apply large vibration or impact to the positioner. It causes trouble to the positioner and itmust be handled very carefully during transportation and operation.

2. If the positioner is used under temperature outside of the specifications, the sealing materialsmay deteriorate quickly and also the positioner may not operate properly.

3. Be sure that the body cover is put on during the operation.

4. If you leave the positioner at the operation site for a long time without using it, put a polythenecover on it so that the rainwater does not harm it in any way.

5. If the atmosphere is of high temp. Or high humidity, take measures to avoid condensation duringshipment.

6. For proper functioning of the positioner, use only factory authorized replacement parts.Substitutions of components can impair the performance of the equipment.

12. TROUBLE SHOOTING

PROBLEM CAUSE WHAT TO DO

Too Low or None Supply Pr. Check Supply Pr.

Damaged Bellow Replace Bellow

Clogged NozzleClean The Nozzle with thehelp of wire provided in thePositioner Cover.

No Response whenInput Signal is Applied

Loose or Wrong Setting of Feedback Lever

Correct Setting/ Tighten

Wrong Orientation of SPAN SwitchCorrect to the Required

Position (Refer Point 7e)

A-M Screw is DisturbedFully tighten the A -MScrew (It has two O- Rings)

Valve Operates Onlyfor 0% & 100% Signali.e. No Response for in

between Signals andActuator Operates Onlyto ON or OFF Position Wrong Connection of OUT1 &

OUT2 Ports

Correct the PneumaticConnection w.r.t. the Positionof SPAN adjustment Switch(Refer Point 7e).

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PROBLEM CAUSE WHAT TO DO

Leakage of A/M Switch Tighten or Replace O Ringsof A/M Switch

Wrong Orientation of SPAN Switch Correct to the RequiredPosition (Refer Point 7e)OUT PUT Pressure

Raised and Stays, DoesNot Come Down

Clogged Fixed OrificeClean the Orifice with thehelp of Wire, provided in thePositioner Cover

OUT PUT Pressure isOperated by A/M

Switch OnlyClogged Nozzle

Clean The Nozzle with thehelp of wire provided in thePositioner Cover.

Disturbed Compensation/ StabilizerSpring

Correct the Positioning of Stabilizer Spring

Hunting is Occurring

Clogged Fixed NozzleClean The Nozzle with thehelp of wire provided in thePositioner Cover

Wrong Setting of Feed Back LeverReadjust the setting of theFeed Back Lever(Refer Point 7c & 7d)

Wrong ZERO, SPAN adjustment Readjust the ZERO & SPAN

Supply Pressure is unstable

Check the Air Leakage fromthe Pneumatic supply ORReplace the Air FilterRegulator

Linearity is not Good

Loose Pneumatic connections in theActuator or Positioner Check & correct