The LONN-ND50 is an inline industrial viscometer that measures liquid viscosity using a metal tuning fork vibration principle. Designed for inline installation in chemical, pharmaceutical, food, and petroleum refining processes, it delivers real-time 4–20mA and RS485 Modbus RTU outputs with Ex d II BT6 explosion-proof certification. Field-configurable via built-in meter menu.
The LONN-ND50 integrated online viscometer represents a significant advancement in process control instrumentation for liquid viscosity measurement. Manufactured by LONNMETER, this inline instrument provides continuous, real-time viscosity monitoring directly in the process pipeline, enabling operators to detect process deviations before they escalate to quality excursions or production losses. The measurement principle relies on metal tuning fork vibration: the fork vibrates at a natural resonant frequency in the process liquid, and the amplitude of that vibration is directly proportional to the viscosity of the surrounding medium. By measuring the electrical drive voltage required to maintain a stable vibration amplitude, the instrument derives an accurate, repeatable viscosity reading.
Unlike traditional rotational viscometers that depend on mechanical bearings, spindles, and seals, the tuning fork design of the LONN-ND50 offers superior long-term reliability in harsh process environments. With no rotating parts to wear, no mechanical seals to degrade, and minimal moving components, the instrument maintains calibration stability over extended operating periods with minimal maintenance. Built-in temperature compensation eliminates system drift caused by ambient and media temperature fluctuations, ensuring consistent accuracy throughout production cycles.
Process engineers choose this industrial viscometer for its combination of robust construction, flexible communication options, and ease of commissioning. The 4-wire 4–20mA active output integrates seamlessly with existing PLC and DCS systems, while the RS485 Modbus RTU interface enables digital communication for remote monitoring, data logging, and integration with plant-wide control networks. On-site configuration through the built-in meter menu allows operators to set custom measurement ranges, apply fine adjustments, and enable temperature compensation without removing the instrument from the pipeline.
The LONN-ND50 industrial viscometer delivers measurement performance tailored to process requirements:
Viscosity Measurement: According to ISO 3219, the international standard for rotational viscometers, accurate viscosity measurement in process applications requires instruments capable of maintaining calibration stability across the target measurement range. The viscosity range of 0–10,000 mPa·s covers the vast majority of industrial liquid process applications, from low-viscosity solvents and acids to moderately viscous syrups, resins, and polymer solutions. Each unit is calibrated and can be specifically scaled to a custom measurement range based on the target process liquid, optimizing resolution and accuracy within that range. The ±2.5% viscosity accuracy meets the requirements of most continuous process control applications in the chemical, pharmaceutical, food, and refining industries. The viscosity reading updates in real time, providing immediate feedback on process changes.
Temperature Compensation: Temperature has a profound effect on liquid viscosity — most liquids experience significant viscosity changes with even modest temperature shifts. The LONN-ND50 online viscometer incorporates built-in temperature compensation that automatically corrects viscosity readings for temperature-induced drift, maintaining accuracy across the full operating temperature range of 0–60°C media temperature and -40–85°C ambient temperature. This feature is critical for applications where process temperatures vary throughout the production cycle.
| Parameter | Specification |
|---|---|
| Signal Mode | 4-wire system |
| Current Output | 4–20mA active (with built-in power source) |
| Digital Communication | RS485, Modbus RTU protocol |
| Power Supply | 24VDC (external; do not load resistor or series-connect to PLC) |
| Load Resistance | Compatible with standard PLC input impedance |
The 4–20mA active output provides reliable signal transmission over long distances without signal degradation. The “active” output means the transmitter generates its own loop power, simplifying installation and eliminating the need for a separate power supply in the current loop. The RS485 Modbus RTU interface supports integration with SCADA systems, data loggers, and plant-wide process control networks.
Important power supply note: The 24VDC supply must be a clean, stable power source. Do not load the power circuit with resistor elements or series-connect to PLC inputs—follow the manufacturer’s wiring guidelines to avoid signal errors or instrument damage.
| Parameter | Specification |
|---|---|
| Explosion Protection Rating | Ex d II BT6 |
| Maximum Working Pressure | <1 MPa |
| Media Temperature | 0–60°C |
| Ambient Temperature | -40–85°C |
| Wet-Wetted Materials | Customizable based on chemical compatibility requirements |
| Installation Orientation | Insertion-style; flow should pass through fork elements |
| Process Connection | Threaded (customizable flanges available) |
The Ex d II BT6 explosion-proof rating, certified under IECEx and ATEX standards, certifies this inline viscometer for deployment in hazardous areas containing flammable gases or vapors (Zone 1/Zone 2). The “隔爆” (flame-proof) construction prevents any internal ignition from propagating to the external atmosphere, protecting both personnel and equipment in petrochemical, refining, and chemical processing environments.
Proper installation is essential for accurate measurement and long-term reliability of the LONN-ND50 inline rotational viscometer:
Monitor viscosity of acids (nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid), bases, solvents (ethanol, methanol), and specialty chemicals in real time. The Ex d II BT6 rating ensures safe operation in hazardous chemical processing environments. Online viscosity measurement enables immediate detection of off-spec batches, reducing waste and improving process yield.
Maintain precise control over pharmaceutical intermediate viscosity during synthesis and formulation. The digital RS485 Modbus RTU output integrates with pharmaceutical process control systems for complete data traceability. Suitable for high-purity solvent measurement and medical intermediate production processes.
Monitor viscosity in sugar solutions (sucrose-water systems, as defined by ICUMSA), oils, syrups, and liquid food products. The real-time measurement supports consistent product quality in confectionery, beverage, and dairy processing. The food-grade wetted material options ensure compliance with sanitary design requirements.
Deploy in distillation tower applications for real-time monitoring of crude oil, gasoline, and diesel viscosity. The inline rotational viscometer provides continuous data for refinery process optimization, helping engineers maintain product specifications and maximize refining efficiency. The explosion-proof rating is mandatory in refining environments.
Measure viscosity of industrial wastewater, chemical treatment solutions, and process fluids in environmental monitoring applications. Support for MODBUS RTU communication enables integration with environmental monitoring SCADA systems for automated data collection and reporting.
Control viscosity in lotions, creams, and liquid cosmetic formulations during production. The LONN-ND50 industrial viscometer provides the precision and reliability required for quality-critical consumer product manufacturing.
The LONN-ND50 employs a metal tuning fork vibration measurement principle that differs fundamentally from traditional rotational viscometers:
Viscosity-Amplitude Relationship: The tuning fork vibrates at a natural resonant frequency when immersed in the process liquid. Higher-viscosity liquids exert greater damping force on the vibrating fork, reducing its oscillation amplitude. The instrument measures the electrical drive voltage required to maintain a constant, stable vibration amplitude — this drive voltage is directly proportional to the viscosity of the surrounding liquid. Through calibration against certified viscosity standards, the voltage signal is converted to an accurate viscosity reading in mPa·s.
Signal Processing: Advanced signal processing electronics continuously analyze the drive voltage required to maintain the target vibration amplitude, converting this measurement to a viscosity value in real time. The instrument’s digital display shows the current viscosity reading, and the 4–20mA and RS485 outputs transmit the data to control systems and data acquisition platforms.
Temperature Compensation: An integrated temperature sensor continuously monitors media and ambient temperatures. Built-in compensation algorithms correct viscosity readings for temperature effects, ensuring accuracy across the full operating range without requiring manual temperature correction calculations.
This measurement approach offers significant advantages over alternative technologies: no rotating parts to wear or break, no pressure-sensitive membranes, minimal moving components, and excellent long-term stability. The tuning fork design is inherently resistant to fouling and coating, making it suitable for process liquids that might clog or coat alternative sensor designs.
Tuning Fork Vibration — No Rotating Parts: Unlike traditional inline rotational viscometers that rely on motor-driven spindles, the LONN-ND50 uses a free-vibrating tuning fork. With no bearings, shafts, or seals, the instrument eliminates the most common failure modes in rotational viscometry and maintains calibration stability over extended periods.
Explosion-Proof for Hazardous Areas: The Ex d II BT6 certification enables safe deployment in petrochemical, refining, and chemical processing environments where flammable vapors are present.
Wide Viscosity Range: The 0–10,000 mPa·s range covers the majority of industrial liquid processes, and custom range calibration optimizes accuracy for your specific application.
Flexible Output Options: 4–20mA active current output and RS485 Modbus RTU digital communication provide compatibility with virtually any process control system or data acquisition platform.
Field-Configurable: Built-in meter menu allows on-site range setting, fine adjustment, and temperature compensation configuration without removing the instrument from service.
Wide Temperature Range: The -40–85°C ambient temperature rating ensures reliable operation in outdoor installations and environments with extreme temperature variations.
Custom Wetted Materials: Contact materials can be selected based on the specific chemical compatibility requirements of the process liquid, ensuring long-term reliability in corrosive applications.
Q1: What is the difference between the LONN-ND50 and a standard inline rotational viscometer?
The LONN-ND50 uses a metal tuning fork vibration principle rather than a rotating spindle. The vibrating fork has no bearings or mechanical seals to wear, providing superior long-term stability and eliminating one of the most common failure modes in traditional rotational viscometers. This design also reduces maintenance requirements and improves measurement reliability in fouling or coating-prone process liquids.
Q2: What is the viscosity measurement range of the LONN-ND50?
The standard range is 0–10,000 mPa·s, covering most industrial liquid processes from low-viscosity solvents to moderately viscous formulations. For applications requiring measurement outside this range, consult LONNMETER about custom calibration options. The unit can be scaled to a specific subrange within the full range to maximize resolution for your target application.
Q3: Is the LONN-ND50 suitable for explosive environments?
Yes. The LONN-ND50 carries an Ex d II BT6 explosion-proof certification , making it suitable for deployment in hazardous areas containing flammable gases or vapors (Zone 1/Zone 2 per IECEx/ATEX classifications).
Q4: What maintenance does the LONN-ND50 require?
The tuning fork design minimizes maintenance requirements—no rotating parts to lubricate or replace. Periodic calibration verification is recommended. The built-in meter menu supports field calibration checks and adjustments. Ensure the electrical compartment remains sealed and the process connection integrity is maintained.
Q5: How do I integrate the LONN-ND50 into an existing PLC or DCS system?
The instrument provides two output options: a 4–20mA active current output compatible with standard analog input cards, and an RS485 Modbus RTU digital output for direct communication with PLCs, DCS systems, or SCADA platforms. The Modbus register map provides viscosity, temperature, and diagnostic data.
Q6: Can the measurement range be customized for my specific process liquid?
Yes. The LONN-ND50 supports custom range calibration. During commissioning, the instrument can be scaled to your specific viscosity measurement range, maximizing accuracy and resolution for your target process conditions. Contact LONNMETER for application-specific calibration services.
Q7: What are the installation orientation requirements?
Install the instrument with the process flow passing through the vibrating fork elements. In partial-fill or low-flow conditions, ensure liquid flows upward through the measurement section to keep the fork fully immersed. Avoid locations with excessive external vibration, and maintain proper grounding practices during electrical installation.
LONN-ND50 Integrated Online Viscosity Meter
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