Guided Wave Radar Level Transmitter Installation Checklist

What is Guided Wave Radar Level Transmitter?

• Level Transmitters are crucial components in industrial process control systems, particularly for accurate level measurement in challenging environments. 
• These transmitters use radar pulses guided along a probe, making them effective for measuring levels of liquids, solids, and even in situations involving steam, foam, or low dielectric constant materials.
• The installation of a Guided Wave Radar Level Transmitter is a critical process that requires careful planning, precision, and adherence to safety protocols. 
• This guide provides a comprehensive installation procedure for Guided Wave Radar Level Transmitters, ensuring safety, precision, and optimal performance.

Step:1 Pre-Installation Considerations

Safety Precautions

• Before beginning the installation, isolate all potential energy sources, including electrical, hydraulic, and pneumatic, that could activate the transmitter. 
• Following the LOTO procedures prevents accidental activation during installation.
• Wear yourself with appropriate PPE based on the specific hazards of the process environment. 
• This includes safety glasses, gloves, hearing protection, and respirators, particularly if the installation site involves hazardous chemicals or confined spaces.
• Familiarize yourself with emergency shutdown protocols and ensure that emergency equipment, such as eyewash stations and fire extinguishers, is readily accessible.

Project Documentation Review

• Obtain and review the manufacturer’s installation manuals, technical specifications like Instrument Data Sheet /Specification, and calibration certificates. 
• These documents provide essential information, such as mounting procedures, wiring configurations, and environmental conditions suitable for the specific GWR model.
• Refer to the Instrument Loop Diagrams (ILD), Piping and Instrumentation Diagrams (P&ID), Instrument Hook-Up Diagrams, Instrument Location Layout, Instrument Cable Schedule and wiring diagrams. 
• These drawings ensure the correct integration of the GWR transmitter into the process system and help avoid any misalignment or improper connections.
• Verify that the GWR transmitter has been pre-calibrated to the specific requirements of the process. Ensure that calibration certificates are available and meet the required standards.

Click here for Types of Engineering Drawings and Documents used in Instrumentation

Measurement Blind Zone

• Ensure that the highest material level in the tank does not enter the radar’s measurement blind zone to avoid inaccuracies.

Distance from Tank Wall

• Maintain a sufficient distance between the transmitter probe and the tank wall to prevent reflections and measurement errors. 
• The minimum recommended distance from the tank wall is 1/10 of the measuring range, with a minimum of 300mm.

Probe Positioning

• The transmitter should be installed so that the cable or rod probe is as perpendicular as possible to the surface of the medium being measured. 
• This ensures accurate readings and minimizes interference from reflections.

Explosion-Proof Requirements

• If the transmitter is installed in an explosion-proof area, ensure compliance with national and local regulations for hazardous areas. 
• The intrinsically safe housing, typically made of aluminum, must be grounded properly.

Step:2 Site Preparation

• The location should minimize interference from internal tank obstructions, such as ladders, agitators, and heating coils. 
• The GWR transmitter should be installed away from the feed inlet and discharge outlet to avoid flow disturbances that can affect measurement accuracy.
• Evaluate the site for environmental hazards such as extreme temperatures, corrosive chemicals, and explosive atmospheres.
•  Ensure that the transmitter’s housing and materials are compatible with these conditions and meet the necessary protection standards (e.g., NEMA, IP ratings).

Step:3 Mounting the Transmitter

Flange Alignment 

• Align the transmitter flange with the mounting flange on the tank. Misalignment can cause stress on the transmitter or tank, leading to inaccurate readings or equipment damage.

Probe Positioning

• The probe (rod or cable) should be centered in the tank and perpendicular to the liquid or solid surface. 
• Ensure that the probe does not contact the tank walls, as this can generate false echoes.

Probe Clearance

• Maintain a minimum clearance of 300mm from the tank wall and at least 30mm from the tank bottom to avoid measurement errors caused by reflections or contact with the tank.
• The bottom of the probe should be at least 30mm from the tank bottom. Maintain a minimum distance of 200mm between the probe and any obstacles inside the tank.

Secure Mounting

• Use manufacturer-recommended bolts, washers, and nuts. Tighten bolts in a crisscross pattern to distribute pressure evenly and prevent warping.
• Refer to the torque specifications provided by the manufacturer to avoid over-tightening, which can damage the transmitter or the tank mounting flange.

Avoid Feed and Discharge Ports

• To reduce the risk of interference and turbulence affecting measurements, install the GWR transmitter away from feed and discharge ports.

Optimal Installation Position

• For solid powders or liquids, it is recommended to install the transmitter at 1/4 or 1/6 of the tank’s diameter. 
• Ensure the metal can does not touch the tank wall or bottom within the entire measuring range.

Rod-Type GWR Installation

• Suitable for liquids with dielectric constants ≥1.8 and viscosities ≤500cst, with a maximum range of 6 meters. 
• Center and secure the rod probe to avoid contact with the tank wall.

Dual-Cable GWR Installation

• Ideal for low dielectric constant liquids or light solid powders (dielectric constant ≥1.6) with a range up to 30 meters. 
• Ensure cables are evenly spaced and free of obstructions.

Threaded Connections

• Limit thread length to 15mm and keep the short pipe height ≤100mm. For pipes >200mm in diameter, use a special flange with a “horn interface” to prevent echo-related errors.

Transmitter in Plastic Tanks 

• Use a metal flange or plate for installations on plastic tanks to maintain accurate readings.

Step:4 Electrical Installation

Power Source and Grounding

• Before making electrical connections, ensure the power supply to the GWR transmitter is disconnected and locked out.
•  Install electrical conduits from the power source to the transmitter’s enclosure, adhering to local electrical codes.
• Proper grounding is essential for safety and to prevent signal interference. 
• Connect the designated grounding point on the transmitter enclosure to the plant grounding system using a suitable grounding wire.

Wiring

• Follow the wiring diagram provided by the manufacturer meticulously. This ensures correct connections for power, control signals, and feedback devices.
• Choose cables appropriate for the voltage, current, and environmental conditions. Securely terminate cables using appropriate connectors, and avoid leaving any loose or exposed wires.

Sealing and Protection

• Seal conduit entries with grommets or fittings to maintain the transmitter’s ingress protection rating. 
• This protects internal components from moisture, dust, and other contaminants.
• For installations in humid environments or outdoor locations, ensure that cable glands are tightened, and cables are looped downward to prevent water ingress.

Step:5 Installation Precautions

Outdoor Installation

• When installing outdoors or in humid environments, take measures to prevent moisture ingress by tightening the cable gland and positioning the cable to loop downward.

Cutting Excess Cable

• If the cable is too long, cut it from the bottom after disconnecting the power, remove the weight, and then reinstall it after cutting. 
• Ensure that the parameters are reset after reinstallation. For cable type GWR with casing, avoid cutting the cable yourself; instead, return it to the manufacturer.

Waveguide Installation

• For waveguide installations, use insulating brackets to maintain concentric alignment between the probe and waveguide. 
• Incorrect alignment can cause strong false echoes, affecting measurement accuracy.

Step:6 Verification and Calibration

Pre-Commissioning Checks

• Conduct a thorough inspection of the installation to ensure all mechanical and electrical connections are secure, and there is no debris or loose parts that could interfere with the transmitter’s operation.
• If possible, manually verify the probe movement within its operating range to ensure smooth operation and absence of binding.

Calibration and Configuration

• Once safety checks are completed, energize the transmitter slowly. Begin with a low power setting to check for any immediate issues.
• Refer the instrument data sheet of the transmitter and verify the configuration of parameters.
• Follow the manufacturer’s guidelines to calibrate the transmitter. This involves setting the zero and span values, adjusting the probe length, and configuring any built-in diagnostic or communication settings.
• Use reference points on the tank (such as known levels) to verify the accuracy of the transmitter after calibration. Make any necessary adjustments to fine-tune the measurement.

 System Integration and Commissioning

• Ensure the GWR transmitter is correctly integrated into the plant’s control system. This includes setting up communication with the Distributed Control System (DCS) or Programmable Logic Controller (PLC) and configuring alarms and safety interlocks.
• Perform a complete functional test of the transmitter in conjunction with the process control system. 
• This involves simulating various process conditions and ensuring the transmitter provides accurate and reliable readings.
• Conduct a final inspection after commissioning to confirm that all installation, calibration, and testing procedures were followed correctly. Ensure that all safety measures, such as grounding and sealing, are in place.

Step:7 Post-Installation Considerations

Documentation

Maintaining detailed records of the installation, calibration, and ongoing maintenance is essential for the long-term performance of the GWR transmitter. 

• Document all steps of the installation process, including any deviations from standard procedures and all calibration settings. 
• This documentation is critical for future maintenance, troubleshooting, and audits.
• Ensure that all calibration data is recorded and stored along with the instrument’s documentation. 
• This includes pre-installation calibration certificates and any on-site adjustments made during the installation.

 Maintenance and Troubleshooting

Regular inspections and adherence to the manufacturer’s guidelines will help in preventing issues and ensuring that the transmitter continues to operate effectively in your industrial process environment.

• Establish a regular maintenance schedule based on the manufacturer’s recommendations. 
• This includes periodic inspection of the probe for buildup, checking the tightness of mechanical and electrical connections, and verifying calibration accuracy.
• In the event of operational issues, refer to the manufacturer’s troubleshooting guide. Common issues include signal loss due to buildup on the probe, moisture ingress into the electronics, and incorrect calibration settings.
• Continuously monitor the environment around the transmitter for any changes, such as increased moisture or temperature fluctuations, that could affect the performance of the GWR transmitter.

Downloadable checklist for installation of the Guided Wave Radar Level Transmitter

This below checklist should help ensure that the installation of the Guided Wave Radar Level Transmitter is thorough and adheres to best practices. 

Refer the below link for the Downloadable checklist for installation of the Guided Wave Radar Level Transmitter

FAQs on Radar Level Transmitter

How to Install a Radar Level Transmitter

1. Choose Location: Pick a spot away from feed and discharge ports to avoid interference.
2. Mount the Transmitter: Align and secure the transmitter, keeping the probe at least 300mm from the tank wall and 30mm from the bottom.
3. Connect Wires: Follow the wiring diagram for power and signal connections. Ensure proper grounding.
4. Check Calibration: Power up the transmitter, calibrate it according to the manufacturer’s instructions, and verify accuracy.

What is the Working Principle of a GWR Type Level Transmitter?

A Guided Wave Radar (GWR) level transmitter works by sending radar pulses along a probe. These pulses reflect off the surface of the material (liquid or solid) and return to the transmitter. The device measures the time it takes for the pulses to return and calculates the material level based on this time.

What is the Construction of a Radar Level Transmitter?

A radar level transmitter typically consists of:

• Radar Transmitter: Generates radar pulses.
• Probe: Conducts the radar pulses through the material.
• Receiver: Detects reflected pulses.
• Electronics: Processes the signals and converts them into level measurements.
• Housing: Protects internal components and ensures durability.

What is a Guided Wave Radar Level Transmitter?

A Guided Wave Radar (GWR) level transmitter is an instrument used to measure the level of materials (liquids or solids) in tanks or silos. It sends radar pulses along a probe and measures the time it takes for these pulses to reflect back from the material surface, providing accurate level measurements even in challenging conditions.

What is the working principle of GWR level transmitter?

The GWR level transmitter is highly accurate and can measure levels even in challenging conditions like foam, steam, or low dielectric constant materials.

The working principle of a Guided Wave Radar (GWR) level transmitter is based on time-domain reflectometry. 

1. Radar Pulse Emission: The GWR transmitter sends short radar pulses down a probe (rod or cable) that is inserted into the tank or vessel.
2. Reflection of Pulses: When these radar pulses encounter the surface of the material (liquid or solid) inside the tank, they are reflected back up the probe.
3. Signal Processing: The transmitter measures the time it takes for the radar pulses to travel down the probe, reflect off the material surface, and return to the transmitter.
4. Level Calculation: Based on the time delay between sending and receiving the pulses, the transmitter calculates the distance to the material surface. This distance is then used to determine the level of the material in the tank.