RELEBAL Solutions
Partial Stroke Testing and Smart Valve Positioners
Partial Stroke Testing (PST) and Smart Valve Positioners for Control and Safety Systems
At Nordenflow, we supply smart valve positioners and partial stroke testing (PST) solutions designed to ensure accurate valve control and reliable safety system performance.
Positioners control valve movement and feedback, while PST systems verify that shutdown valves will operate correctly when required, without interrupting the process.
These technologies are critical in applications where control accuracy, system diagnostics, and functional safety must be maintained over time.
Partial Stroke Testing (PST) Overview
Partial Stroke Testing (PST) systems verify the operational readiness of ESD valves without interrupting production or shutting down the process.
PST performs a controlled partial movement of the valve (typically 10–20% of the full stroke), confirming that the valve, actuator, and mechanical components respond as expected.
These systems can detect a significant portion of dangerous undetected failure modes, including stiction, stem damage, and actuator degradation — reducing the risk of failure during a real shutdown event.
Technical Advantages Modules ICO4-PST
SIL 3 Performance Enhancement
Integrated PST logic reduces Probability of Failure on Demand (PFDavg), enabling systems to achieve or maintain SIL 3 safety performance.
Functional Safety Compliance
Designed in accordance with IEC 61508 and IEC 61511 standards for safety instrumented systems.
Extended Proof-Test Intervals (PTI)
Automated PST allows safe extension of full-stroke test intervals, reducing shutdown frequency and supporting compliance strategies.
Dual Technology Support
Positioner-based PST enables detailed diagnostics, while solenoid-based PST supports fast response verification in safety loops.
Advanced Diagnostic Data
Captures valve signatures including torque trends, friction behavior, and pressure conditions to support predictive maintenance.
Features — ICO4-PST Modules
Function: Periodic proof testing of ESD valves without full closure
Stroke Range: Adjustable 5–25%
Test Initiation: Local push-button or remote signal
Reset: Automatic reset after test completion
Feedback: Continuous position monitoring (4–20 mA or digital)
Diagnostics: Real-time valve performance tracking
Compatibility: Pneumatic, hydraulic, electro-hydraulic actuators
Integration: ESD and SIS systems
Functional Safety: SIL 2 / SIL 3 capable
Standards: IEC 61508 / IEC 61511
Certifications: ATEX, IECEx, FM, CSA
Design: Suitable for hazardous environments
Interface: Local visual indication and LED status
Operation: Manual override and fail-safe protection
When You Need Partial Stroke Testing (PST)
PST is required when safety valve performance must be verified without interrupting production, particularly in systems where failure on demand is not acceptable.
When ESD valves must be tested regularly without full shutdown, especially in continuous process plants.
When safety systems require SIL compliance and periodic verification of valve functionality.
When valve performance degradation (stiction, slow response, actuator issues) must be detected before a real shutdown event.
When operating in industries such as oil & gas, LNG, power, and process plants where unplanned downtime and safety risks must be minimized.
When maintenance strategies require predictive diagnostics instead of reactive shutdown-based testing.
Smart Valve Positioners — High-Precision Control by IMI
Nordenflow provides high-performance smart valve positioners from :contentReference[oaicite:0]{index=0}, designed for precise modulating control and advanced valve diagnostics.
Positioners act as the control interface between the automation system and the valve, ensuring accurate positioning, stable loop performance, and reliable feedback.
With support for HART, Foundation Fieldbus, and Profibus communication protocols, these devices enable seamless integration into modern control and safety systems.
When You Need Smart Valve Positioners
Smart valve positioners are required when precise valve control, stable loop performance, and reliable feedback are critical to process efficiency and safety.
When precise control of flow, pressure, or temperature is required in modulating control loops.
When control loops are unstable due to hysteresis, dead-band, or inconsistent actuator response.
When accurate valve position feedback is required for monitoring, diagnostics, and system integration.
When integration with digital control systems (HART, Foundation Fieldbus, Profibus) is needed.
When predictive maintenance and real-time diagnostics are required to reduce downtime and improve reliability.
Common in process control systems across oil & gas, LNG, power, and industrial plants where stable and accurate valve control is essential.
Technical Advantages
Flexible Signal Integration
Supports multiple input signals including 4–20 mA, HART, Profibus, and Modbus, enabling seamless integration with modern DCS and control systems.
High-Precision Valve Control
Pneumatic output control (0.2–1.0 bar) ensures accurate valve positioning and stable modulation under varying process conditions.
Adaptable Architecture
Available in analog, digital, electro-pneumatic, and smart configurations to match application complexity and control requirements.
Accurate Position Feedback
Feedback via potentiometer or encoder provides precise valve position monitoring for diagnostics and control validation.
Robust Industrial Design
Aluminum or SS316 housings with IP66 / NEMA 4X protection and hazardous area certifications ensure reliable operation in harsh environments.
Standardized Installation
NAMUR and IEC 60534 mounting interfaces allow easy integration with a wide range of control valves and actuators.
Fast Commissioning and Setup
Auto-calibration and self-diagnostics reduce setup time and ensure optimal performance from initial installation.
Local Monitoring and Configuration
Optional LCD interface provides real-time status, configuration, and troubleshooting directly at the device level.
Why IMI Positioners via Nordenflow
We supply high-performance positioners from :contentReference[oaicite:0]{index=0}, selected and configured based on real application requirements, not catalog selection.
Application-based selection aligned with control loop behavior, actuator characteristics, and process requirements.
Integration with valve, actuator, and instrumentation systems to ensure stable and reliable operation.
Support for digital communication protocols and system-level diagnostics.
Supply flexibility for projects, upgrades, and replacement requirements.
Evaluate Your Valve Control and Safety Performance
Share your system details to determine whether smart positioners, PST solutions, or a combined approach is required for reliable control and safety performance.
• Valve type and actuator configuration
• Control mode (on/off, modulating, safety system)
• Signal type and control system (4–20 mA, HART, Fieldbus)
• Performance concerns (instability, slow response, diagnostics)
• Safety requirements (SIL level, ESD, testing strategy)
• Maintenance strategy and testing intervals