Coriolis mass flow meters are widely used in chemical processing, food production, oil & gas, and pharmaceutical industries due to their high accuracy, direct mass measurement, and multi-parameter output. However, like any precision instrument, long-term operation can lead to measurement deviations or system alarms.

Understanding common faults and their solutions helps operators restore measurement accuracy quickly, reduce downtime, and extend instrument lifespan. This guide summarizes the most common Coriolis flow meter issues and provides a practical troubleshooting approach.

1. Basic Troubleshooting Workflow

Before addressing specific faults, technicians should follow a simple diagnostic sequence. Many problems can be identified within minutes through basic checks.

Visual Inspection

Check the following:

• Flow direction matches the arrow on the nameplate

• No mechanical damage, corrosion, or leakage

• Mounting bolts and flanges are properly tightened

Power Supply and Wiring

Confirm that:

• Power supply is DC 24V (±10%)

• Signal cables are intact and not damaged

• Grounding is reliable and properly installed

Process Condition Verification

Make sure the process conditions meet operational requirements:

• The pipe is completely filled with fluid

• No air bubbles or two-phase flow

• Temperature and pressure are within the meter’s rated range

Check Alarm Codes

Modern Coriolis transmitters provide self-diagnostic alarm codes, which can quickly identify sensor, wiring, or process problems.

2. Three Core Coriolis Flow Meter Faults and Solutions

The following three issues account for the majority of field service cases.

2.1 Zero Drift (Most Common Problem)

Zero drift means the meter shows a small flow value even when the fluid is static.

Possible Causes and Solutions

Installation stress

• Cause: Pipeline stress affects sensor vibration.

• Solution: Reinstall the meter and tighten flanges evenly to eliminate external force.

No on-site zero calibration

• Cause: Factory calibration does not compensate for installation conditions.

• Solution: Perform zero calibration with a full pipe and no flow.
  Repeat calibration three times for stability.

Valve leakage

• Cause: Slight internal leakage creates actual flow.

• Solution: Inspect and replace leaking valves.

Sensor tube fouling

• Cause: Deposits inside the measuring tube change vibration characteristics.

• Solution: Clean the sensor tubes.

Electromagnetic interference

• Cause: Nearby motors, inverters, or power cables.

• Solution: Improve shielding and grounding.

Gas-liquid two-phase flow

• Cause: Entrained gas bubbles disturb vibration measurement.

• Solution: Increase back pressure or install a gas-liquid separator.

2.2 Unstable Measurement / Signal Fluctuation

Flow readings fluctuate significantly or become unstable.

Possible Causes and Solutions

Gas bubbles or cavitation

• Cause: Gas entering the pipeline disrupts density and vibration signals.

• Solution: Install an upstream separator and increase system pressure.

Pipeline vibration

• Cause: Pumps or compressors transmit vibration to the sensor.

• Solution:

• Install the meter at least 5 meters away from pumps or compressors

• Add flexible connectors or vibration isolation brackets.

Electromagnetic interference

• Cause: Signal cables routed with power cables.

• Solution: Separate signal and power wiring.

Low damping setting

• Cause: Response time too short for fluctuating conditions.

• Solution: Increase the damping time constant in the transmitter.

Rapid temperature or pressure changes

• Cause: Process instability.

• Solution: Stabilize the process conditions.

2.3 No Flow Indication / Zero Output

The display shows zero even when the process is running.

Possible Causes and Solutions

Power supply failure

• Check whether 24V power supply is present and polarity is correct.

Blown fuse

• Replace the fuse with the same specification.

Loose or broken signal cable

• Tighten terminals or replace damaged cables.

Pipe not completely filled

• Ensure the pipe is fully filled and remove trapped air.

Incorrect installation direction

• Reinstall the meter according to the flow direction arrow.

3. Other Possible Coriolis Flow Meter Faults

In addition to the major problems above, the following issues may also occur during operation.

Inaccurate Density Measurement

Possible causes:

• Incorrect configuration parameters

• Two-phase flow

• Installation stress

• Temperature exceeding the rated range

Solutions:

• Re-enter nameplate parameters

• Eliminate gas-liquid mixture

• Reinstall the meter to remove pipeline stress

• Restore normal temperature conditions

Power Present but No Signal Output

Possible causes:

• Measuring tube blockage

• Drive coil failure

• Sensor or cable damage

Solutions:

• Clean the sensor tubes

• Repair or replace the drive coil

• Replace damaged sensors or cables

4. Preventive Maintenance Best Practices

Preventive maintenance significantly reduces the risk of unexpected failures.

Perform Regular Zero Calibration

• Recommended every 3–6 months

• Recalibrate after installation or major temperature changes

Keep the Measuring Tube Clean

• For scaling or viscous fluids, perform periodic cleaning

Avoid Long-Term Low Flow Operation

• Enable low flow cutoff to prevent measurement instability

Maintain Adequate Back Pressure

• Prevent gasification and two-phase flow

Establish Maintenance Records

Maintain a detailed log including:

• Fault events

• Troubleshooting actions

• Calibration history

This helps engineers quickly identify recurring problems.

Conclusion

Coriolis mass flow meters deliver exceptional accuracy and reliability, but proper troubleshooting and maintenance are essential for long-term performance. Most problems—such as zero drift, unstable readings, and zero output—are typically related to installation stress, process conditions, or electrical issues.

By following a systematic troubleshooting approach and implementing preventive maintenance practices, operators can ensure measurement stability, reduce downtime, and maximize the service life of Coriolis flow meters.

If you need professional advice or product recommendations, feel free to contact us anytime.