bennypass.com - Flowserve Positioner PMV D2 Series

Flowserve Positioner PMV D2 Series - D2XNU-S23PVB-Z4X0X

The PMV D2 Series digital positioner works by using digital technology to precisely control a valve's actuator based on an input signal from a controller. It operates by receiving an electronic signal (e.g., 4-20 mA), comparing it to the actual valve position, and using a digital algorithm to move the actuator to the correct position. The process involves digital processing for precise control, and it includes features like automatic calibration and advanced diagnostics.

2AAA

Working principle

Receiving input: The positioner receives an electronic control signal from a system controller, such as a 4-20 mA signal.
Measuring actual position: It uses internal feedback mechanisms, which can be a position feedback module or an optical indicator, to determine the current position of the valve.
Digital comparison and calculation: A digital processor compares the desired position (from the input signal) with the actual position. It then calculates the necessary adjustments to achieve the desired position with high precision.
Actuating the valve: Based on the digital calculation, the positioner sends a pneumatic signal to the actuator to move the valve to the correct position. For a single-acting positioner, this means it uses a built-in valve to control the air supply to the actuator.
Continuous adjustment: This process repeats continuously, allowing the positioner to make small, precise adjustments to maintain the valve's position against variations in pressure or load

Key features

High precision: Offers very high control precision, even on small valves.
Auto-calibration: Includes a one-button auto-calibration feature that tunes the positioner in seconds.
Digital diagnostics: Features advanced digital diagnostics via the ValveSight software for monitoring valve health and performance.
Modular design: Allows for flexible mounting for both rotary and linear actuators and supports various communication protocols like HART, Profibus PA, and Foundation Fieldbus.
Optional components: Can be optionally equipped with a 4-20 mA position feedback, limit switches, an LCD display (D22), or a dome indicator.

Core operating principle

The working principle of the D2 series can be broken down into four key components that work together in a feedback loop:

Input signal processing: The positioner receives a 4–20 mA electrical control signal from an external controller, such as a distributed control system (DCS).
Position sensing: The D2 uses an internal potentiometer connected to the actuator's shaft to measure the actual valve position. This gives the positioner real-time feedback on the valve's location.
Control logic: The positioner's microprocessor compares the input signal (the desired position) with the feedback signal (the actual position). Based on this comparison, it determines if the valve needs to move and in which direction.
Pneumatic output: The microprocessor sends a command to a pneumatic relay. This relay precisely regulates the flow of compressed air to and from the actuator.

If the valve needs to open, the relay increases the air pressure to the actuator.
If the valve needs to close, the relay decreases the air pressure.
Once the desired position is reached, the relay stabilizes the pressure to hold the valve in place.

Key features enhancing performance

Several features of the D2 series further enhance its performance and ease of use:

Auto-calibration: A key feature is its single-button auto-calibration, which automatically tunes the positioner to the valve and actuator assembly in seconds. This greatly simplifies commissioning.
High precision and resolution: The digital control allows for very high precision, even for small valve movements. A high-resolution output ensures the actuator can be positioned accurately.
HART communication: The D2 supports the Highway Addressable Remote Transducer (HART) protocol, which allows for two-way digital communication. This enables remote configuration, monitoring, and diagnostic capabilities from a central control system.
Diagnostics: Advanced versions can be paired with software like ValveSight to provide predictive diagnostics. It continuously monitors the health of the entire valve assembly, including the actuator, and provides actionable insights to prevent unplanned shutdowns.
Versatility: The positioner's modular design allows it to be used for both rotary and linear valve applications. It is also available in different configurations, such as single-acting and double-acting versions.