Table of Contents
This is applicable for Calibration of Samson control valves (model- 3730-3). So in this article “Control valve Calibration” we will learn the calibration of Samson control valves (model- 3730-3).
Definition
The Electro pneumatic positioner is attached to pneumatic control valves. it is used to assign the valve stem position to the control signal. the input signal received from a control system is compared to the travel or rotational angle of control valve, and a pneumatic signal pressure is produced. the positioner basically consists of an electrical travel sensor system, an analog i/p converter with downstream air capacity booster and the electronic unit with a microcontroller.
These are used in a process industry for the controlling of valve opening as per process requirement. It is mandatory to calibrate them at regular intervals of time.
Procedure requirement
Safety Precautions
- Ensure that tools necessary for performing the task i.e. Screw Driver set, Multimeter, D.E. Spanner.
- If the Control valve is an EIS, take necessary precautions for maintenance of EIS & follow EIS procedure too.
- Wrong implementation of procedure/implementation without proper communication may lead to accidents or plant disturbance.
Calibration Procedure
Proper procedure is necessary to ensure the satisfactory operation.
- Ensure the Maximo Work order (print copy after WO released) is ready to perform the calibration on Control valve.
- Ensure the work permit/Maintenance request form to confirm the maintenance on control valve.
- There are several methods to calibrate the control valve-
- Calibration
- Nominal Calibration
- Zero calibration
Max-Initialization Based On Maximum Range
The positioner determines travel/angel of rotation of the closing member from the closed position to the opposite side and adopts this travel/angle of rotation as the operating range from 0 to 100%.
Enable Configuration
Turn Rotary pushbutton and select code-3, Display: No
Press Rotary Pushbutton, Code-3 blinks
Turn Rotary Pushbutton, Display-Yes
Press Rotary Pushbutton, Display- Configuration Enable symbol.
Select the Initialization mode
Turn Rotary pushbutton and select code-6
Press Rotary Pushbutton
Turn Rotary Pushbutton, Select Max
Press Rotary Pushbutton to confirm the Max as the initialization mode.
Start Initialization
Press INIT key to start initialization.
NOM- INITIALIZATION BASED ON NOMINAL RANGE
The calibrated sensor allows the effective valve travel to be set very accurately. During the initialization process the positioner checks whether the control valve can move through the indicated nominal range without collision.
If this is the case, the indicated nominal range is adopted with the limits of travel/angle range start and travel/angle range end as the operating range.
Enable Configuration
Turn Rotary pushbutton and select code-3, Display: No
Press Rotary Pushbutton, Code-3 blinks
Turn Rotary Pushbutton, Display-Yes
Press Rotary Pushbutton, Display- Configuration Enable symbol.
Enter the pin position and nominal range
Turn Rotary pushbutton and select code-4
Press Rotary Pushbutton, Code-4 blinks
Turn Rotary pushbutton and select Pin position on lever.
Press Rotary Pushbutton
Turn Rotary pushbutton and select code-5
Press Rotary Pushbutton, Code-5 blinks
Turn Rotary pushbutton and select Nominal travel/angel
Press Rotary Pushbutton
Select the Initialization mode
Turn Rotary pushbutton and select code-6
Press Rotary Pushbutton
Turn Rotary Pushbutton, Select Max
Press Rotary Pushbutton to confirm the Max as the initialization mode.
Start Initialization
Press INIT key to start initialization.
ZERO CALIBRATION- BASED ON ZERO ERROR
Enable Configuration
Turn Rotary pushbutton and select code-3, Display: No
Press Rotary Pushbutton, Code-3 blinks
Turn Rotary Pushbutton, Display-Yes
Press Rotary Pushbutton, Display- Configuration Enable symbol.
Select the Initialization mode
Turn Rotary pushbutton and select code-6
Press Rotary Pushbutton
Turn Rotary Pushbutton, Select ZP
Press Rotary Pushbutton to confirm the ZP as the initialization mode.
Start Initialization
Press INIT key to start initialization.
- Fill the checklist Now Calibration procedure is now complete take it in process.
- Hand back the work permit & Close the WO.
REFERENCEs
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