Yokogawa Level Transmitter: Key Standards, Physical Properties, and Engineering Applications

Types of Yokogawa Level Transmitters

Yokogawa is a global leader in industrial automation and control systems, offering a comprehensive range of level transmitters designed for accurate, reliable, and safe fluid level measurement across diverse industries. These include oil & gas, chemical processing, power generation, water treatment, and food & beverage. Each type of transmitter utilizes a different measurement principle, making it suitable for specific applications, media types, and environmental conditions.

Radar Level Transmitter

Yokogawa's radar level transmitters use high-frequency electromagnetic waves (microwaves) to determine the distance to the surface of a liquid or solid. The device emits a radar signal from an antenna, which travels down to the material surface and reflects back to the sensor. The time-of-flight of the signal is precisely measured, allowing the transmitter to calculate the level with exceptional accuracy—even in challenging conditions.

Advantages

• Non-contact measurement (no media contact)
• High accuracy and reliability
• Unaffected by changes in temperature, pressure, or vapor density
• Excellent for volatile, corrosive, or viscous fluids
• Low maintenance requirements

Limitations

• Higher initial cost compared to other technologies
• Performance can be affected by heavy foam, dust, or agitated surfaces
• Antenna selection is critical for optimal performance

Best for: High-precision applications, hazardous environments, sealed tanks, and corrosive or extreme process conditions

Hydrostatic Pressure Level Transmitter

This type of Yokogawa level transmitter operates on the principle of hydrostatic pressure. It measures the pressure exerted by the liquid column above the sensor, which is typically mounted at the bottom of a tank. Since pressure is directly proportional to the height and density of the liquid, the transmitter converts the pressure reading into a level measurement. It's ideal for open or vented tanks where atmospheric pressure compensation is applied.

Advantages

• Simple and reliable measurement principle
• Cost-effective solution for many applications
• Good accuracy for consistent-density liquids
• Well-suited for open tanks and sumps
• Durable and easy to install

Limitations

• Requires direct contact with the process medium
• Accuracy depends on consistent fluid density
• Not suitable for vacuum or pressurized sealed tanks without additional compensation
• Potential for clogging in slurry or dirty applications

Best for: Water and wastewater, chemical storage, fuel tanks, and applications with stable liquid density

Ultrasonic Level Transmitter

The Yokogawa ultrasonic level transmitter uses high-frequency sound waves to measure the distance to the surface of a liquid or solid. It emits an ultrasonic pulse from a transducer, which travels through the air until it hits the material surface and reflects back. The time it takes for the echo to return is used to calculate the level. This non-contact method is effective in open or vented vessels where there is a clear path for sound waves.

Advantages

• Non-contact measurement
• No moving parts, low maintenance
• Effective in open tanks and reservoirs
• Resistant to many chemicals
• Good for water, wastewater, and environmental monitoring

Limitations

• Sensitive to temperature gradients and vapor layers
• Performance affected by foam, dust, or heavy turbulence
• Not suitable for pressurized or vacuum tanks
• Sound-absorbing materials can reduce accuracy

Best for: Open tanks, ponds, clarifiers, and outdoor applications with minimal vapor or foam

Capacitance Level Transmitter

Yokogawa's capacitance level transmitters measure fluid levels by detecting changes in electrical capacitance between two electrodes (probes). As the level of the material changes, the dielectric constant between the probes changes, altering the capacitance. This change is converted into a level signal. These transmitters can be used for point level detection or continuous level measurement and are effective for both liquids and bulk solids.

Advantages

• Can measure a wide variety of liquids and slurries
• Effective for interface level detection (e.g., oil/water)
• Compact design with no moving parts
• Good for conductive and non-conductive liquids (with proper calibration)
• Reliable in high-temperature and high-pressure environments

Limitations

• Requires contact with the process medium
• Coating or buildup on the probe can affect accuracy
• Calibration is sensitive to changes in dielectric constant
• Not ideal for low-dielectric materials like some solvents

Best for: Chemical processing, food & beverage, pharmaceuticals, and applications requiring interface or slurry level detection

Technology	Measurement Type	Contact Required?	Accuracy	Best Suited For
Radar	Non-contact	No	Very High	Sealed tanks, corrosive media, high precision
Hydrostatic	Contact	Yes	High (density-dependent)	Open tanks, water, consistent liquids
Ultrasonic	Non-contact	No	Medium to High	Open tanks, outdoor use, clean liquids
Capacitance	Contact	Yes	Medium to High	Slurries, interface detection, varied media

Expert Tip: When selecting a Yokogawa level transmitter, always consider the process conditions—including fluid properties, temperature, pressure, tank geometry, and potential for foam or vapor. For sealed tanks with vapors or condensation, radar is often the most reliable choice. For cost-sensitive open tank applications, hydrostatic or ultrasonic may be ideal.

Important Features of Yokogawa Level Transmitters

Yokogawa level transmitters are engineered for precision, resilience, and seamless integration in industrial environments. Selecting the right level measurement solution requires careful evaluation of key performance characteristics. Below is a detailed breakdown of the most important features that make Yokogawa transmitters a trusted choice across oil & gas, chemical, power, and water treatment industries.

High Measurement Accuracy

Pressure-Based Level Measurement

Yokogawa differential pressure (DP) level transmitters deliver exceptional accuracy, typically within ±0.1% of the reading. By measuring hydrostatic pressure, these devices provide reliable liquid level data even in challenging process conditions such as fluctuating densities or vapor pressures. Advanced sensor technologies minimize drift and ensure long-term stability, reducing calibration frequency and maintenance costs.

Radar Level Technology

For non-contact level measurement, Yokogawa’s guided wave radar (GWR) and free-space radar transmitters offer precision down to ±0.1 inch (2.5 mm), depending on model and configuration. These systems are ideal for applications involving foam, vapor, or turbulent surfaces. With minimal maintenance requirements and immunity to changes in temperature, pressure, or dielectric properties, radar transmitters ensure consistent performance in demanding environments.

All Yokogawa transmitters process and transmit measurement data in real time, enabling immediate response from control systems. Digital signal processing reduces noise and enhances resolution, ensuring that displayed or logged values reflect true process conditions with minimal lag.

Exceptional Durability and Environmental Resistance

Designed for operation in the harshest industrial settings, Yokogawa level transmitters are built to withstand extreme physical and chemical stresses. Key durability features include:

High-Temperature Tolerance: Capable of operating in environments up to 315°C (600°F), making them suitable for steam drums, reactors, and high-temperature distillation columns.

High-Pressure Ratings: Some models support pressures up to 40 MPa (5,800 psi), ideal for supercritical processes and high-pressure storage vessels.

Corrosion-Resistant Materials: Wetted parts are constructed from materials such as Hastelloy, tantalum, and ceramic coatings to resist aggressive chemicals like acids, alkalis, and solvents.

Robust Enclosures: Housings meet IP66/IP67 and NEMA 4X standards, providing protection against dust, moisture, and mechanical impact—even in outdoor or washdown environments.

Advanced Communication and Integration Capabilities

Yokogawa level transmitters support a wide range of communication protocols, enabling seamless integration into modern process automation systems. This ensures data can be efficiently collected, monitored, and analyzed across the plant network.

Communication Protocol	Application Benefit	Compatibility
HART®	Enables two-way digital communication over standard 4-20 mA wiring for configuration and diagnostics	Compatible with most legacy and modern control systems
Foundation™ Fieldbus	Supports fully digital, multi-drop networks for improved signal integrity and reduced wiring costs	Ideal for new digital plant installations
Modbus RTU/TCP	Facilitates integration with PLCs, SCADA, and third-party systems via serial or Ethernet	Widely used in water/wastewater and power industries
Profibus PA	Enables process automation networks with intrinsic safety in hazardous areas	Common in European and chemical industry applications

In addition, select models offer optional wireless communication modules (e.g., ISA100 Wireless), allowing remote monitoring in hard-to-reach or hazardous locations. Operators can access real-time level data and diagnostic alerts from central control rooms, improving safety and operational efficiency.

Comprehensive Support and Service

Customer-Centric Support: Yokogawa provides global technical support to ensure maximum uptime and performance. Their team of field engineers and application specialists are available to assist with installation guidance, troubleshooting, calibration, and repair services. Whether through on-site visits, remote diagnostics, or training programs, Yokogawa helps customers resolve issues quickly and maintain continuous production.

The company offers flexible service options including:

Repair and Calibration Services: Factory-certified technicians restore transmitters to original specifications using genuine parts.

Field Support: On-demand engineering assistance for complex installations or emergency repairs.

Software Tools: Configuration and diagnostic software (e.g., BRAIN Terminal, FieldMate) for easy setup and maintenance.

Training Programs: Technical workshops and online resources to empower in-house teams.

This commitment to service ensures that Yokogawa level transmitters not only perform reliably but are also supported throughout their entire lifecycle.

Commercial Uses of Yokogawa Level Transmitters

Yokogawa level transmitters are precision-engineered instruments trusted across multiple industries for accurate, reliable, and safe liquid and material level monitoring. Leveraging advanced technologies such as radar, ultrasonic, and pressure-based sensing, these transmitters provide real-time data integration with control systems to enhance operational efficiency, ensure process safety, and minimize downtime. Their robust design allows them to perform under extreme temperatures, pressures, and corrosive environments, making them ideal for critical industrial applications.

Water Treatment Plants

Yokogawa level meters play a vital role in water treatment facilities by continuously measuring water levels in storage tanks, clarifiers, sedimentation basins, and effluent discharge systems. Accurate level monitoring ensures optimal hydraulic retention time, prevents overflow, and maintains consistent flow rates through various treatment stages—including coagulation, filtration, and disinfection.

• Non-contact radar and ultrasonic sensors prevent fouling in sludge-prone environments
• Integrated analog and digital outputs enable seamless communication with SCADA and PLC systems
• High IP-rated enclosures ensure durability in humid and chemically active atmospheres
• Self-diagnostics detect sensor issues before they impact operations

Key benefit: Ensures regulatory compliance with environmental discharge standards through precise level control

Oil and Gas Industry

In upstream, midstream, and downstream operations, Yokogawa’s level transmitters are essential for monitoring crude oil, refined products, LNG, and associated gases in storage tanks, separators, and processing vessels. Their ability to operate reliably under high pressure, extreme temperatures, and explosive atmospheres makes them a preferred choice in hazardous zones.

• Radar transmitters offer excellent performance in high-vapor and foaming conditions
• Intrinsically safe and explosion-proof models meet ATEX, IECEx, and SIL certifications
• Guided wave radar (GWR) provides stable readings in turbulent or low-dielectric media
• Remote monitoring capabilities support offshore and unmanned facility operations

Critical advantage: Prevents overfilling incidents and ensures inventory accuracy for custody transfer applications

Chemical Manufacturing

Precise level measurement is non-negotiable in chemical processing, where incorrect levels can lead to dangerous reactions, spills, or equipment damage. Yokogawa's chemical level gauges are engineered to withstand aggressive acids, alkalis, solvents, and reactive compounds commonly found in reactors, distillation columns, and intermediate storage tanks.

• Corrosion-resistant wetted parts made from Hastelloy, PTFE, or ceramic coatings extend service life
• Built-in safety alarms trigger automatic shutdowns during overfill or low-level conditions
• Digital communication protocols (HART, Foundation Fieldbus) allow integration into safety instrumented systems (SIS)
• Stable performance in vacuum and pressurized vessels ensures process integrity

Safety note: Reduces risk of hazardous leaks and environmental contamination through fail-safe monitoring

Food and Beverage Industry

Yokogawa level transmitters are widely used in food processing, beverage production, and packaging lines to monitor liquids such as water, juices, milk, oils, syrups, and alcohol. Hygienic design and compliance with food safety standards make them suitable for clean-in-place (CIP) and sterilize-in-place (SIP) processes.

• Sanitary models with 3-A and EHEDG certification ensure compliance with FDA and EU hygiene regulations
• Smooth, crevice-free surfaces prevent bacterial growth and facilitate easy cleaning
• Accurate level control supports fermentation consistency, batching accuracy, and filling operations
• Stainless steel housings resist washdown chemicals and high-pressure cleaning

Quality impact: Maintains product consistency and reduces waste in high-speed production environments

Expert Insight: When selecting Yokogawa level transmitters, consider the process medium, environmental conditions, and required certifications. For example, guided radar is ideal for low-dielectric liquids like solvents, while non-contact radar excels in steamy or dusty environments. Always pair the transmitter with proper mounting accessories and calibration services to ensure long-term accuracy and reliability.

Industry	Typical Application	Recommended Technology	Key Feature
Water Treatment	Clarifier & Wet Well Level Monitoring	Ultrasonic / Non-Contact Radar	Fouling resistance, IP68 rating
Oil & Gas	Crude Oil Storage Tanks	Guided Wave Radar (GWR)	Explosion-proof, SIL2 certified
Chemical	Reactor Vessel Level Control	Capacitance / GWR with PTFE Coating	Corrosion resistance, alarm integration
Food & Beverage	Mixing Tank & Fermentation Vessels	Radar with Sanitary Flange	3-A certified, CIP/SIP compatible

Additional Benefits Across Industries

• Remote Diagnostics: Real-time health monitoring reduces unplanned maintenance and increases uptime
• Scalability: Compatible with Yokogawa’s CENTUM and Exaquantum platforms for enterprise-wide visibility
• Energy Efficiency: Optimized pump and valve control based on level data reduces energy consumption
• Data Logging: Historical trend analysis supports predictive maintenance and process optimization
• Global Support: Yokogawa offers local calibration, installation, and technical support in over 60 countries

How to Choose Yokogawa Level Transmitters: A Comprehensive Buyer’s Guide

Selecting the right Yokogawa level transmitter is essential for ensuring accurate, reliable, and safe level measurement across industrial applications. With a wide range of technologies including radar, ultrasonic, and pressure-based systems, Yokogawa offers advanced solutions tailored to diverse environments. This guide outlines the critical factors buyers should evaluate when choosing the optimal level transmitter for their specific operational needs.

Important Note: Always verify compatibility with your process media, environmental conditions, and control system requirements. Incorrect selection can lead to measurement inaccuracies, equipment damage, or safety risks.

1. Required Measurement Type and Technology

Yokogawa provides three primary level measurement technologies—radar, ultrasonic, and pressure-based—each suited to different process conditions:

• Radar Transmitters (e.g., EJA Series): Ideal for high-pressure, high-temperature environments with foam, vapors, or steam. Non-contact radar (FMR) models offer high accuracy in challenging conditions without media contact.
• Ultrasonic Sensors: Best for open tanks or non-pressurized vessels with clean liquids. They are cost-effective but can be affected by vapors, foam, or dust, which may interfere with signal transmission.
• Pressure Level Transmitters: Suitable for closed tanks where hydrostatic pressure correlates directly to liquid level. These are robust and ideal for dense or viscous fluids, especially when installed at the tank bottom.

Expert Tip: In tanks with heavy foam or turbulent surfaces, guided wave radar (GWR) often outperforms ultrasonic sensors by maintaining signal integrity through the foam layer.

2. Tank Characteristics and Installation Requirements

The physical design and configuration of the tank significantly influence transmitter selection:

• Tank Type: Use non-contact radar or ultrasonic sensors for simple, open-top tanks. For enclosed or complex vessels with agitators, baffles, or internal structures, guided wave radar or pressure transmitters are more reliable.
• Level Range: Match the sensor’s measurement span to the required level range. Yokogawa’s radar transmitters can measure up to 40 meters, while ultrasonic models typically cover up to 15 meters.
• Installation Constraints: Consider nozzle size, mounting orientation, and accessibility. Some radar models support top-mounted installation even in narrow nozzles, minimizing retrofitting costs.

3. Working Conditions and Environmental Factors

Ensure the selected transmitter can withstand the operational environment:

• Temperature Range: Yokogawa transmitters support extreme temperatures—from cryogenic applications to over 400°C (752°F) with appropriate seals and materials.
• Pressure Tolerance: Pressure transmitters are rated for specific pressure classes. For high-pressure reactors or steam drums, choose models with appropriate diaphragm seals and overpressure protection.
• Chemical Compatibility: Evaluate wetted materials (e.g., 316L stainless steel, Hastelloy, Teflon) against the process fluid to prevent corrosion or degradation.
• Application-Specific Challenges: Ultrasonic sensors are excellent for clean water and wastewater, while pressure and radar sensors are preferred for oils, chemicals, and slurry applications.

4. Industry-Specific Applications and Use Cases

Yokogawa level transmitters are engineered to meet the demands of various industries:

• Pharmaceuticals: Pressure transmitters are ideal for sterile, hygienic environments such as bioreactors and mixing tanks, where precision and cleanability are critical. Models with hygienic flanges (e.g., DIN 11851) ensure compliance with sanitary standards.
• Oil & Gas: Radar and pressure transmitters excel in hydrocarbon storage tanks, offshore platforms, and separators. They provide stable readings despite vapor buildup, foam, and fluctuating temperatures.
• Chemical Processing: Guided wave radar is often used for corrosive or viscous media, offering consistent performance in aggressive chemical environments.
• Water & Wastewater: Ultrasonic level transmitters are widely used in open channels, sumps, and reservoirs due to their ease of installation and low maintenance.

5. Data Communication and Integration Needs

Modern level transmitters must seamlessly integrate into existing control and monitoring systems:

• Communication Protocols: Choose models that support your system’s protocol—options include 4-20mA with HART, Modbus RTU/ASCII, Profibus PA, and Foundation Fieldbus.
• Wireless Connectivity: For remote or hard-to-access locations, consider Yokogawa’s wirelessHART-enabled transmitters, which allow real-time monitoring without extensive cabling.
• Multi-Sensor Networks: In large tank farms or process lines requiring multiple sensors, ensure compatibility with centralized SCADA or DCS systems for synchronized data collection and alarm management.
• Smart Diagnostics: Advanced models offer predictive maintenance features, such as echo curve visualization and self-diagnostics, enhancing reliability and reducing downtime.

Technology	Best For	Limited In	Recommended Yokogawa Series
Radar (Non-Contact)	High-pressure tanks, steam, foam, volatile chemicals	Very low dielectric fluids (e.g., propane, butane)	FMR66, FMR67
Guided Wave Radar	Viscous fluids, small tanks, low dielectric media	Tanks with heavy coating or build-up on probes	FGR20, FGR30
Ultrasonic	Open tanks, clean water, wastewater	Pressurized tanks, vapors, foam, dusty environments	YTA510, YTA520
Pressure Transmitter	Dense liquids, closed tanks, hydrostatic measurement	Low-density fluids, vapor pressure fluctuations	EJA-E, EJA-F

Pro Tip: When upgrading legacy systems, leverage Yokogawa’s interoperability features. Many transmitters support analog output with digital communication (HART), allowing gradual integration into modern control networks without full system overhauls.

Final Selection Checklist

• ✔ Confirm the measurement technology aligns with your fluid and tank conditions
• ✔ Verify temperature, pressure, and chemical compatibility
• ✔ Ensure the measurement range covers minimum and maximum operating levels
• ✔ Select appropriate communication protocol for system integration
• ✔ Consider installation, maintenance access, and environmental protection (IP/NEMA ratings)
• ✔ Consult Yokogawa’s technical support or use their selection software for complex applications

Choosing the right Yokogawa level transmitter ensures long-term accuracy, safety, and process efficiency. By carefully evaluating measurement type, tank characteristics, environmental conditions, application needs, and communication requirements, buyers can make informed decisions that optimize performance and reduce lifecycle costs. When in doubt, partnering with Yokogawa-certified engineers or distributors can help tailor the best solution for your specific process.

Frequently Asked Questions About Capacitance Level Transmitters

Q1: Which factors should one consider when using a capacitance level transmitter?

When selecting and installing a capacitance level transmitter, several key factors must be evaluated to ensure accurate and reliable operation. The most critical consideration is the dielectric properties of the material being measured. Yokogawa capacitance sensors are particularly effective for non-conductive (insulating) liquids such as oils, fuels, solvents, and liquid plastics, where the sensor can detect changes in capacitance as the level changes.

However, these sensors are not ideal for conductive media like water or aqueous solutions, as the electrical conductivity can interfere with the sensor’s ability to measure capacitance accurately. In such cases, alternative technologies like guided wave radar or ultrasonic level sensors may be more appropriate.

Another important factor is the tank geometry. Capacitance transmitters perform best in tanks with consistent, predictable shapes—particularly cylindrical or vertical tanks—where the relationship between level and capacitance remains linear. Irregularly shaped or horizontally mounted tanks can introduce measurement inaccuracies due to variable surface area exposure.

Additional considerations include:

• Coating or buildup on the probe, which can alter capacitance readings over time.
• Installation position—the sensor must be mounted vertically and away from agitators or inlet nozzles.
• Grounding requirements, especially in conductive vessels or when measuring conductive liquids.

Q2: Which factors affect the performance of these transmitters?

While capacitance level transmitters are robust and reliable, their performance can be influenced by various environmental and process conditions. Understanding these factors helps in minimizing errors and ensuring long-term accuracy.

• Temperature Variations: Changes in process temperature can affect the dielectric constant of the medium and cause expansion or contraction of materials, leading to drift in readings. High-quality Yokogawa transmitters include temperature compensation features to mitigate this effect.
• Pressure Fluctuations: Although capacitance sensors are generally unaffected by pressure changes in liquid applications, extreme pressure shifts can impact mechanical integrity or seal performance, especially in high-pressure vessels.
• Tank Vibrations: Mechanical vibrations from pumps, mixers, or nearby equipment can cause false signals or physical damage over time. While radar sensors might misinterpret vibrations as level changes, advanced Yokogawa models use signal filtering and damping algorithms to reject such noise.
• Steam and Vapor: In high-humidity or steam-filled environments, condensation on the probe or insulator can create false capacitance, leading to inaccurate measurements. Proper insulation and ventilation help reduce this risk.
• Material Buildup: Sticky or viscous substances may coat the sensor, altering its effective length and dielectric response. Regular inspection or use of coated probes can address this issue.

Modern Yokogawa capacitance transmitters are engineered with intelligent diagnostics and filtering capabilities that significantly reduce the impact of these interferences, making them suitable for demanding industrial environments.

Q3: Do these transmitters require any periodic maintenance?

Capacitance level transmitters are known for their low maintenance requirements due to the absence of moving parts. Unlike mechanical float systems, they do not suffer from wear and tear under normal operating conditions. However, while routine servicing is not mandatory, proactive inspections are strongly recommended to maintain measurement integrity and prevent unexpected failures.

Key inspection points include:

• Corrosion Check: Inspect the sensor rod, housing, and connections for signs of corrosion, especially in harsh chemical or marine environments. Corrosion can alter electrical properties and compromise sealing.
• Probe Cleanliness: Look for residue, coating, or fouling on the sensing element. Accumulated material can cause false high-level readings or reduced sensitivity.
• Seal Integrity: Examine O-rings and process seals for cracks or leaks, particularly in pressurized or outdoor installations.
• Mounting Stability: Ensure the transmitter is securely mounted and not subjected to excessive stress or movement.
• Blockage Inspection: Check for obstructions around the sensor, especially in tanks with agitators or solids, which could damage the probe or interfere with measurement.

If any worn or damaged components are found during inspection, they should be replaced promptly using manufacturer-recommended parts. Scheduled visual checks—typically every 6 to 12 months—can extend service life and avoid unplanned downtime.

Q4: How can one prolong the life of these level transmitters?

Maximizing the lifespan of a capacitance level transmitter involves a combination of proper installation, environmental protection, and preventive care. By following best practices, users can ensure years of reliable service and accurate level monitoring.

• Stable Power Supply: Ensure the transmitter receives clean, stable voltage within the specified range. Voltage spikes or electrical noise from nearby motors can damage internal electronics. Use surge protectors or isolation barriers if necessary.
• Wiring Inspection: Periodically check cables and connections for fraying, moisture ingress, or loose terminals. Damaged wiring can lead to signal loss or short circuits. Use shielded cables and proper grounding techniques to reduce electromagnetic interference.
• Thermal Protection: Avoid prolonged exposure to extreme temperatures beyond the sensor’s rated limits. Excessive heat can degrade electronic components and insulation, while freezing conditions may damage seals or cause condensation. Install thermal insulation or sun shields in outdoor applications.
• Regular Calibration: While capacitance transmitters are stable, periodic calibration (annually or after major process changes) ensures long-term accuracy. Use certified reference methods to verify output and adjust zero/span settings as needed.
• Environmental Sealing: Confirm that all enclosures and conduit entries are properly sealed against dust and moisture, especially in washdown or humid areas.
• Software Diagnostics: Leverage built-in diagnostic tools available in smart Yokogawa transmitters to monitor health, detect anomalies early, and schedule interventions before failure occurs.

By integrating these practices into a comprehensive asset management strategy, operators can significantly extend the operational life of capacitance level transmitters, reduce maintenance costs, and enhance process safety and efficiency.