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OPERATING INSTRUCTION

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OPERATING INSTRUCTION Powered By Docstoc
					1. Product introduction

  1.1 General introduction

  Model CHX700 Electro-pneumatic Positioner can transfer 4-20mA DC

output current signal of adjuster or IO of computer into an output

pneumatic signal, and drive adjustable valve to realize angle or linear

displacement by single action or double action cylinder and closed loop

control by the cam feedback system, so as to realize accurate angle or

linear displacement in proportion to the input signal.

  1.2 Operating principle

      Structural diagram of the electro-pneumatic positioner




  (1) Torque coil                  (9) Diaphragm cylinder
  (2) Magnetic steel               (10) Main beam
  (3) Balance beam                (11) Pilot valve
  (4) Feedback spring             (12) Cylinder
  (5) Resetting shaft             (13) Internal feedback spring
  (6) Cam                         (14) Throttle valve
  (7) Lever                       (15) Zero-nut
  (8) Nozzle                      (16) Circuit board


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  The torque coil (1) in the permanent magnetic field (2) forms a torque

in proportion to the signal current inside the coil, the torque acts on the

balance beam (3). The feedback spring (4) forms a reverse torque

corresponding to the angle of the resetting shaft on the balance beam (3).

The angle of the resetting shaft (5) will be changed into the displacement

of the lower end of the feedback spring (4) by the cam (6) and lever (7),

in proportion to the angle.

  The nozzle (8) checks whether the torque of the balance beam (3)

balances. When increasing the given signal, the balance beam (3) will

close the nozzle (8), by this time the pressures in the nozzle and the upper

piston end of the diaphragm cylinder (9) will increase, the main beam (10)

and the valve core of the pilot valve (11) will move downward. The pilot

valve (11) will make air to flow to the upper piston end of the cylinder

(12), and the air of the lower end will discharge from the outlet of the

pilot valve. The differential pressure between two piston ends of cylinder

(12) will make the piston to overcome friction force and moving torque.

Rotating the resetting shaft (5) will make its angle to correspond with the

given signal, by this time the torque of the balance beam (3) balances.

The internal feedback spring (13) will form a negative feedback between

the first stage amplifier and the second one. The first stage amplifier

includes the nozzle (8), the throttle valve (14) and the diaphragm cylinder

(9), the second stage amplifier includes the pilot valve (11) and the


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cylinder (12). The feedback spring (4) and the internal feedback spring

(13) can be used to change the position on the balance beam (3) for

changing the dynamic response of the positioner and applying to different

cylinders. The zero-nut (15) can be used to adjust zero setting. The

potentiometer on the circuit board (16) can be used to regulate the

full-scale adjustment.

  1.3 Technical performance

Input signal: 4-20 mA DC        0-20 mA DC

Partial range: 4-12mA DC        12-20mA DC

Input resistance: 220±10

Max feedback angle: 90°

Straight distance: 20-140mm

Control direction: positive action and back action

Relation between distance and signal: linear

Air supply pressure: 0.14-0.8 Mpa

Influence of air supply pressure: <0.2%/10 kpa

Ambient temperature:-25~+85℃

Environmental temperature:    ≤0.05%℃

Preventive class: Ip54

Gas consumption: 0.5m3n/h

Servo slide valve hole matched with the actuator: Ø4, Ø6

Performance of more stable load of the acurator:


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Blind area: ≤0.4%

Hysteresis plus: <0.7%

Linearity: <±1%

Vibration influence: (1.5g-100Hz) ≤1%

Structural materials are treated with glutamic acid and there is

electro-dusting aluminum coating on their outer surfaces. Cover is made

of polycarbonate and internal parts are made of stainless steel and

aluminum-alloy, which are corrosion resisting materials with surface

treatment technique.

Inlet: G1/2 or M20×1.5

Suitable cable: Ø5-Ø10

Air pipe connection: ZG1/4”

Weight: 2.3kg or so

2. Main parts of Model CHX700 Electro-pneumatic Positioner

2.1 Zero-nut, see the structural diagram and stereogram of the positioner

Clockwise or counter clockwise rotation can change the zero point of the

positioner.




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2.2 Full-scale potentiometer adjustment




The divided circuit can be used to adjust full-scale. The adjustment of

potentiometer Rz can change the full-scale of the positioner at terminal.

Note: The adjustment shall be carried out slowly so as not to damage the

potemtiometer.

Note: The zero-nut shall be used to adjust the lower limit, the full-scale

potentiometer shall be used to adjust the upper limit.

2.3 Reversing block.     Reversion can be used to change the operating

direction of airflow holes C1 and C2 of the positioner. There are marks R

and D on both sides.

   As shown in figs:




The reversing block and the case wall have corresponding oblique planes,

and you shall take care of them in assembly.




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2.4 Servo slide valve

    Servo slide valve is a pneumatic output power component in the

positioner and the serial positioners are fitted with the slide valves Ø4,

Ø6. (The Positioners are fitted with slide valve Ø4 as leaving the factory.

If necessary, they can be fitted with slide valve Ø6 singly.)

  The match of slide valve and actuator is determined on hole, cylinder

and cylinder volume.

                 Match of slide valve and actuator

     Hole of                Diameter                      Volume

   slide valve          of actuator Ømm               of cylinder dm3

          Ø4                  <150                          <11

          Ø4                  >150                          >11

2.5 Internal feedback spring and hanger

(See the fig.) There are 5 hanging methods, i.e. A, B, C, D and E. As the

positioner is assembled to the actuator, you can select different hanging

places according to different cylinder volumes of the actuators in order to

change their gains and make the positioner positioned immediately and

stably.




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  Relation of internal feedback spring, hanger and cylinder volume:

   Position               Diameter of                      Volume of

  of spring          cylinder piston Ømm                  cylinder dm3

        a                     <90                            ≤0.5

        b                    90-120                           0.5-1

        c                   120-150                            1-4

        d                   150-240                           4-11

        e                     >240                           11-50



2.6 Throttling orifice

It is on the outside of the positioner case, there is a filter net before it, as

blocking up, it can be dismounted easily and clear dirt with a needle

Ø0.2.

2.7 Feedback cam

2.7.1 Usage

It shall be used according to the control signal range of the positioner, the

signal is full-range or partial-range. Whether the action mode of the

actuator is positive or reverse action and whether its distance mode is

angle distance or straight distance, these are dependent upon the

performance of cams used. The serial positioner uses linear feedback cam,

if users need other feedback cam, please propose it as ordering.

2.7.2 Schematic diagram of angle distance feedback cam


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2.7.3 Schematic table of angle distance feedback cam

          Schematic table of angle distance feedback cam

 Symbol             Description                   Operation mode

                                             Actuator shall be mounted
    →            Clockwise rotation
                                           clockwise at signal 0%-100%.
                                             Actuator shall be mounted
                      Counter
    ←                                       Counter-clockwise at signal
                 clockwise rotation
                                                     0%-100%.
                 0-20mA 4-20mA
  0-100
                     10-50mA
                 4-10mA 0-10mA              The lower end is the starting
   0-50
                     10-30mA                    point, as operation.
                12-20mA 10-20mA
  50-100
                     30-50mA
                                          There is not feedback area on the
                                            arc and the two points shall
    ‥                   -20°              correspond to the ball valve. The
                                           distance will be determined by
                                                        DN.
              Letters indicate working
   A, B
                       faces.




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2.8 Straight distance feedback cam

2.8.1 The working angle of the straight distance feedback cam is 45°. The

basic mode of the straight distance is 16-70mm and the extension mode

of the straight distance is 70-140mm, they can be single-double action or

positive-negative action.

2.8.2 Allowance error in assembly operation

The angle of the feedback cam can be 45°±5°, the positioner can operate

normally by adjusting zero point and span.The stroke distance of the

positioner differ from the nominal stroke of the actuator by 10% generally,

it can operate normally.

2.8.3 Schematic diagram of straight stroke feedback cam




The positive action mounting surface of the straight stroke feedback cam




The negative action mounting surface of the straight stroke feedback cam

→ It indicates this surface is the positive action mounting surface.

← It indicates this surface is the negative action mounting surface.

. It indicates the tangent point of the feedback supporting roller, at half

of the stroke.

3 Adjustment and debugging of the angle stroke positioner


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3.1 Fix and connection

3.1.1 There are over two fixation methods of the positioner, see the

dimension figure.

3.1.2 Connected catcher of the positioner and the actuator, U-type and

H-type.

3.2 Adjustment and debugging of machinery

3.2.1 The actuator shall be controlled to the initial point 0%, before

assembling the positioner to the actuator.

3.2.2 The positioner assembled to the actuator shall ensure the positioner

feedback shaft is concentric with the actuator rotating shaft.

3.2.3 The connecting lever of the positioner connected catcher can not

touch the actuator rotating shaft.

3.2.4 The connection of the positioner connected catcher shall couple

closely.

3.3 Connection of air pipe

3.3.1 The air flew in can operate the actuator from lower limit to the air

blow hole of upper limit, named the up air blow hole of the actuator.

3.3.2 When control signal increase, it will increase the pressure of some

air blow hole (C1, C2) of the positioner, this hole is named the up air

blow hole of the positioner.

3.3.3 Use air pipe and union joint to connect the up air blow hole of the

actuator with the up air blow hole of the positioner.


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3.3.4 Then connect the other two air blow holes and connect the S hole

with the air supply.

Note: When assemble air pipe and union joint, do not drop sealing belt or

wastes into the air pipe.

3.4 Adjustment of mechanical zero

3.4.1 Control the actuator at 0% (initial point)

3.4.2 Assemble and adjust the feedback cam of the positioner according

to the operating mode (see 2.7), the tangent point of the feedback

supporting roller shall point to the starting location, as shown in figure.




Firstly tighten the nut and then the fixed screw.

3.5 Test of mechanical mode

3.5.1 Open the air supply, the cam and the actuator shall be at the starting

points.

3.5.2 Push the balance block (equivalent electrical signal increase), the

actuator will operate from the starting point (lower limit) to upper limit,

the feedback cam will run from the starting point (lower point) to internal

(upper point). Release the balance block, i.e. recover original status.

3.6 Hanging methods of the internal feedback spring


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3.6.1 See Section 2.5, it is dependent upon the actuator.

4. Adjustment and debugging of the straight stroke positioner

4.1 Fix and connection

4.1.1 See the dimension figure for fixation dimensions.

4.1.2 The positioner and the link of the actuator, as shown in figure.




4.2 Adjustment and debugging of machinery

4.2.1 The actuator shall be controlled to a half of stroke, before

assembling the positioner to the actuator. Connect the pressure reducing

valve to the air blow hole of the actuator directly and make the actuator to

be at a half of scale-plate of the stroke by adjusting the output of the

pressure reducing valve.

4.2.2 Assemble the fixation supporter of the positioner to the actuator and

the positioner to the supporter. Make the link of the actuator to insert into

the sliding slot 6mm and adjust the fixation location of the positioner in

order to keep the link and the push bar both perpendicular and adjust the

location of the positioner in order to keep the connection bar at the


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correspondent stroke scale mark of the link of the positioner. Ensure the

positioner to upright and tighten the fixation nut.

4.2.3 The stroke is dependent upon user’s actuator.

4.2.4 The feedback cam of the straight stroke is assembled according to

the operating mode of the positive-negative action of user’s actuator, see

Section 2.8.

4.2.5 The center point of the feedback cam of the straight stroke and the

feedback supporting roller shall be tangent, as shown in figure.




The above figure is the positive action and the stroke is at a half.

Note: It is assembled according to this figure as leaving the factory, if

need other assemble, please propose it in an order.

4.2.6 Tighten the nut of the cam and the fixation screw.

4.2.7 Connection of air pipe

Connect the air blow hole of the positioner with the air blow hole of the

actuator and the air supply according to the operating mode. Adjust the

pressure reducing valve to reach a working pressure.

4.2.8 Open the air supply and check it by the equivalent method of

increasing control signal. (Push the balance block)

4.2.8.1 The pusher of the actuator can drive the connecting bar and the


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link of the positioner and run from the lower limit of the stroke to the

upper limit according to the action mode.

4.2.8.2 The feedback cam is operated upon the action direction.

4.2.8.3 The link of the straight stroke and the feedback cam are in the

basic operating range.

5. Test of the fundamental performance and technical index of the

positioner

5.1 List the input-position relation upon ranges of the angle stroke and the

straight stroke and percentage of the control signal.

5.2 Input right signal

5.3 Adjustment

5.3.1 Turn on the air supply and input signal separately according to the

zero adjustment and the full range adjustment.

5.3.2 The zero-nut shall be used for adjustment of the lower limit and the

full-scale potentiometer shall be used for adjustment of the upper limit.

5.4 Test

5.4.1 After debugging, input electrical signal from upward to downward

and test according to relation of the input signal and the position.

Fundamental performance, linearity, variation, etc. shall meet the needs

of the technical index.

5.4.2 The valve directory board of the positioner shall be assembled and

fixed according to the open and close of the valve.


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6. Application and maintenance

6.1 You shall understand the structure, performance and operating

principle of the positioner and the working modes of the actuator and the

control valve before use, as to use them perfectly and skillfully.

6.2 Clean air supply is the first condition of ensuring the positioner to

operating normally.

6.2.1 The air supply shall be ensured against oil, dust and wet and

inputted into the positioner after filtering.

6.2.2 The air supply shall clean periodically.

6.3 If the positioner operates at a more vibrational site, all fasteners shall

be checked periodically in order to ensure it to operating normally.

7. Trouble shooting of the positioner

7.1 Turn on the air supply, input electrical signal and check faults of the

actuator.

7.1.1 Firstly check the external operating condition of the positioner:

a. Whether all the connection pipes are right and in good condition.

b. Correspondent load of the positioner: The actuator and the valve shall

be controlled.

c. Keep the air supply open and stable.

d. Ensure the control signal in good condition.

7.1.2 Ensure the external condition for no problem and check faults

according to the following flowchart.


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a. The actuator is out of action, as inputting electrical signal.




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b. The positioner is not stable.




c. The balance block is out of action and only at some limit location;

c.1




                                    17
c.2 The balance block is only at 100%.




7.2 Faults and solutions

7.2.1 Make sure that the external condition is 7.1.1.

7.2.2 Big variation
  No.                  Cause                          Solutions
  1      Pressure spring on main plate        Replace the main lever
         loosen (has relation to 2)
  2      Servo slide valve jammed             Clear with cleaning agent
  3      There is interval on connection      Remove the interval
         of link.
  4      The actuator rotating shaft is not   Reassemble and ensure them
         concentric with the positioner       for concentric.
         feedback shaft.
  5      Air pipe leakage                     Check the leakage and seal it
  6      Throttling orifice too dirty         Clean
  7      Nozzle too dirty                     Clean
  8      Feedback shaft dumb                  Dissociate it and clean

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7.2.3 Oscillation (position unstable and oscillating)
  No.                  Cause                      Solutions
  1      Control signal oscillating       Processing signal abnormal
  2      Sliding valve jammed             Clean
  3      There is interval on link.       Remove the interval
  4      Guide board of nozzle too dirty  Clean
  5      Spring deformation               Replace the spring
  6      Feedback shaft dumb              Dissociate it and clean
  7      Positioner and actuator mismatch Make them to match
  8      Pressure variation of air supply Adjust the pressure of air
         big                              supply
  9      Motor jammed                     Replace the motor
8 Ordering information
The following should be marked on an order:




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For example

CHX     7     2   4   A   H

                               H Connection

                               Angle stroke

                               Double action

                               Fundamental type

                               Design serial number




                          20
9 Outline dimension drawing




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Changshu Huaxia Instrument Co., Ltd
Add: Bixi Town, Changshu City, Jiangsu Province

Tel: 0512-52217000

Fax: 0512 52217111

Post code: 215511

Website: www.hx800.com




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Authentication of ISO9001 Quality Control System




        OPERATING INSTRUCTION

                     FOR

 MODEL CHX700 ELECTRO-PNEUMATIC

                POSITIONER




 Changshu Huaxia Instrument Co., Ltd
                Jiangsu China




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                           CONTENT



1. Product introduction…………………………………………………..1

  1.1General introduction……………………………………………….1

  1.2 Operating principle………………………………………………..1

  1.3 Technical performance…………………………………………….3

2. Main parts of Model CHX700 Electro-pneumatic Positioner…………4

  2.1 Zero-nut……………………………………………………………4

  2.2 Full-scale potentiometer adjustment………………………………5

  2.3 Reversing block……………………………………………………5

  2.4 Servo slide valve…………………………………………………..6

  2.5 Internal feedback spring and hanger …………………………….. 6

  2.6 Throttling orifice …………………………………………………7

  2.7 Feedback cam ……………………………………………………7

  2.8 Straight distance feedback cam…………………………………. .9

3 Adjustment and debugging of the angle stroke positioner ……………9

  3.1 Fix and connection………………………………………………10

  3.2 Adjustment and debugging of machinery ………………………10

  3.3 Connection of air pipe …………………………………………10

  3.4 Adjustment of mechanical zero …………………………………11

  3.5 Test of mechanical mode ………………………………………11

  3.6 Hanging methods of the internal feedback spring………………11


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4. Adjustment and debugging of the straight stroke positioner………. .12

  4.1 Fix and connection…………………………………………….. .12

  4.2 Adjustment and debugging of machinery………………………. 12

5. Test of the fundamental performance and technical index of the

positioner……………………………………………………………….14

6. Application and maintenance………………………………………. .15

7. Trouble shooting of the positioner…………………………………. .15

8 Ordering information……………………………………………….. .19

9 Outline dimension drawing…………………………………………. .21




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