December 13, 2024
The ND9000™ is an advanced intelligent valve controller for a wide range of control valve actuators in all industrial sectors, for pneumatic diaphragm-type and cylinder-type actuators for straight- or angle-stroke valves. With unrivaled diagnostics and unique features that ensure the quality of the end product under all operating conditions, supported by Valmet's Neles FieldCare™ lifetime service system, the ND9000 has become a reliable device that ensures future growth. Its good design and unique diagnostic features provide a solid foundation for performance optimization and forward-looking service operations.
ND9000 is a series designation, and for the ND9102H, “9” refers to the ND9000 series, and “10” refers to the enclosure safety rating of “Standard IP66/ NEMA 4×”. NEMA 4×”, ‘2’ refers to the small flow rate, ‘H’ refers to the support of HART communication protocol and the defined input signal range (4-20mA); details are shown below:
The ND9000 series is a microprocessor-based intelligent valve controller with a 4-20mA power supply loop, and supports a minimum 3.6mA input signal when using a HART hand manipulator to operate the device. Local operation can be performed using the controller's local user interface, while remote operation requires a PC with software installed and must be connected to the ND9100H body or control loop.
The valve position is controlled by a powerful 32-bit microprocessor and the relevant measured parameters are the input signal, the valve position with non-contact sensors, the actuator pressure (2 independent measurements), the air supply pressure, the spool valve, the device temperature.
Advanced self-diagnostic technology ensures that all measurement functions work properly. When the input signal and the position measurement are normal, a failure of any of the other measurements will not cause the valve to malfunction. After the electrical signal connection and the air connection to the cylinder have been made, the microprocessor (μC, see Figure 3-1, below) reads the input signals, the position sensor measurements (α), the pressure sensor measurements (Ps, P1, P2), and the slip sensor measurements (SPS). After the control algorithm embedded in the μC detects a deviation of the input signal from α, a new value is calculated and fed to the preamplifier (PR) coil circuit based on the data from the input signal and the sensor, respectively. Changing the current input to the PR changes the control pressure to the slide valve accordingly. The reduced control pressure displaces the spool of the slide valve, which correspondingly changes the actuator pressure. When the spool opens, gas flows to the drive side of the double thin-film actuator and exits the other side of the actuator. The gradually increasing pressure then displaces the diaphragm, driving the actuator and feedback lever or shaft to rotate clockwise. A position sensor (α) measures the rotation and sends it to the μC. Using a control algorithm, the μC begins to adjust the current in the PR, starting from one steady state until the new value generated brings the actuator state to the state that should correspond to the input signal value. The following figure shows the working principle of the positioner:
Local user interface function:
-Local control of valves
-Monitoring of valve position, input signal, temperature, supply and actuator differential pressure
-Guided start function
-LUI (Local User Interface) can be locked remotely to prevent unauthorized access
-Calibration: automatic/manual/linearization
1-point calibration
-Control Configuration: Aggressive, Fast, Optimal, Stable, Maximum Stability
-Mode selection: Auto/Manual
-Rotation: Valve closes with clockwise or counterclockwise rotation
-Dead space
-Low cutoff, cutoff safety range (default 2%)
-Positioner fault action, open/close
-Signal direction: direct/reverse acting
-Actuator type, double/single acting
-HART version: HART 6 or HART 7
-Valve type, rotary/linear IEC/nelesCV Globe/FLI
-Language options: English, German and French
The maintenance required for the ND9000H valve positioner depends on the operating environment and conditions, e.g. the quality of the gas supply, etc. No maintenance is required under normal operating conditions.
Before servicing the ND9000H, make sure that the air supply is disconnected and the pressure is relieved.The ND9000H valve controller consists of the following interchangeable modules: a pre-stage unit, a slide valve assembly unit with sensors, and a communication board with selectable position transmitters. These modules are secured under the cover housing so that if a module fails, it must be replaced with a new module and assembled in a clean, dry environment. After reassembly, coat the screws with anti-loosening thread oil and tighten securely.
a. Front Unit
The front unit should be removed with great care, especially when the housing is removed and the removed parts should not be moved around. Remove the M4 screws with a screwdriver and remove the front unit. Unplug the front stage wiring from the slip sensor circuit board, continue to remove the two M4 screws from the slide valve cover, remove the front unit module vertically, and finally remove the O-ring. To install, place a new O-ring into the slide valve recess, then place the preamp unit in. Confirm that the nozzle is introduced exactly into the O-ring. Use the screws to return the preamplifier body to its correct position, tightening the screws evenly. Re-insert the front unit bipolar cable connector into the slip sensor circuit board, the connector has an anti-misplugging feature. Finally cover the front unit housing and tighten the screws.
b. Slide Valve Assembly
Removal of the slide valve should only be done after the removal of the preamplifier stage. Remove the slide valve assembly by removing three M4 screws and two M3 screws. If necessary, clean the slide valve in accordance with environmental cleanliness requirements and proper procedures. After removing the three M4 screws, vertically remove the slide valve from the retaining groove, holding the end of the valve body finger-tight to prevent the spool from falling out. Carefully clean the spool and body center hole, taking care not to allow sanitary fibers to stick to the spool and body center hole, or to scratch the spool and body joint. The throttle is mounted under the slide valve in the retaining groove and should also be cleaned after the slide valve is removed. Note that each slide valve body corresponds to a unique spool, so spools cannot be interchanged, nor can the orientation of the spools be changed (as identified in the lower right corner of Figure 3-6).
When reassembling, verify that the pads are properly placed in the grooves at the bottom of the slide valve assembly. Install the slide valve into the retaining groove and tighten the three M4 screws and two M3 screws. Verify that the O-ring is in full contact with the inside of the groove, and finally install the front stage unit directly as described above.
c. Communication circuit board
Loosen the M8 countersunk screws on the position indicator and remove the position indicator from the shaft rod. Remove the pre-stage housing and further remove the circuit board cover secured by four M3 screws. Take care to discharge your own static electricity before touching the circuit board. Remove the 4 M3 fixing screws and hold one side to take the circuit board out vertically upwards. Handle the circuit board carefully, it is best to only touch the edges of the board. Reinstallation is the reverse of the above. Figure 3-7 shows the outline of the communication circuit board.
