FAQ
Frequently Asked Questions About Ultrasonic Flow Measurement

The clamp-on sensors are mounted on the outside of the pipe—therefore, it is not necessary to open the pipe. They are secured using metal chains, metal straps, or mounting rails. Coupling compound is applied to the underside of the sensor head to ensure acoustic coupling between the sensor and the pipe.

Installation advantages:

• No process interruption
• No need to cut into the pipe
• No risk of leaks
• Installation takes only a few minutes

In most cases, no preparation of the pipe surface is necessary. Only very rough or corroded areas should be sanded smooth beforehand.

Katronic devices feature an acoustic sensor positioning assistant and an integrated setup wizard that guides you step by step through the installation process. This makes it possible to set up the measurement system and obtain accurate readings in just a few minutes.

Yes. In addition to an integrated media library of standardized liquids and gases, you can enter custom substance data. To do this, select “User” from the media selection menu. The flow meter will then prompt you to enter the following three parameters:

• Kinematic viscosity (mm²/s)
• Density (kg/m³)
• Sound velocity in the medium (m/s)

Often, the speed of sound in a medium (the speed at which sound travels through a fluid) is unknown. In this case, you will find a list of parameters for non-standard media in the appendix of the operating instructions. If no suitable values are available there, please contact our technical support.

Please note that manually entered parameters are valid only for the specified temperature.

For initial estimates, a water-like medium can also be used. To do this, select “Water” as the medium from the menu. Although this setting is not exact, water has average material properties that are necessary for the flowmeter’s three measurement parameters. Selecting “Water” instead of another medium is not ideal, but it does allow for initial, orientational measurements. Please note that river water, wastewater, deionized water, or sewage sludge are also considered “water” and differ only in their solids content.

For precise measurements, however, project-specific material data is recommended.

No, as long as the paint layer adheres firmly and is uniform. Only if the paint is peeling or if there are multiple, different coats should the surface be prepared locally with a suitable abrasive.

The achievable accuracy depends on the flow meter's application:

• Volume flow without process calibration: ±1% to ±3%
• With on-site process calibration: ±0.5%
• Flow velocity: ±0.5%
• Measurable flow velocity range: 0.01 to 25 m/s; reproducibility: 0.15% of the measured value.

Katronic's clamp-on sensors cover a very wide range of pipe diameters, from 10 mm to 6,500 mm.

No. The measuring devices operate without wear because:

• there are no moving parts,
• no components that come into contact with the medium are used, and
• the sensors are mounted on the outside of the pipe wall and are made of stainless steel (Note: This applies to all types except the P-sensors).

Corrosion, pressure, or the effects of the process medium do not affect the sensors. Therefore, maintenance is not necessary.

When fully charged, the KATflow 200 and KATflow 230 portable measuring devices can operate continuously for up to 24 hours. A full charge takes about twelve hours.

Enabled analog outputs or additional functions on the KATflow 230 increase power consumption, which reduces battery life. Disable the outputs in the menu when not in use.

For long-term measurements, the KATflow 210 is available with a battery life of up to 100 days. The meter offers various battery configurations and can be operated in three different measurement modes to enable the longest possible measurement periods.

If a KATflow flow meter does not achieve the expected battery life, please contact Katronic or our sales partners. All Katronic flow meters can also be operated using AC power, ensuring continuous operation, even if only temporarily.

Standard cable lengths range from 2.5 m to 30 m, depending on the sensor type. Extension cables up to 200 m are available as an option. You can find a detailed overview in our product brochure.

First, make sure the flow meter is fully charged. Connect the device to the charger. The flow meter should now turn on, and the battery indicator should flash to show that it is charging. If this does not happen, please contact Katronic.

If the flow meter is running on AC power, turn it off, unplug it from the power source, and try restarting it by holding down the <ENTER> button.

If the device still won’t turn on, open the battery compartment, remove the batteries, and check their condition. Then reinsert the batteries and repeat the

startup process. If the screen remains dark, the batteries may need to be replaced. For more information, contact the manufacturer.

All permanently installed flow meters turn on automatically as soon as power is supplied. If this does not happen, please perform the following checks:

1. Check the power supply:

Use a multimeter to ensure that current is flowing at the flow meter’s main connection.

2. Check the fuses:

Check the flow meter’s fuses and replace them if necessary.

3. Check the wiring:

Use the wiring diagram provided in the user manual to ensure that the wiring is correct.

4. Check the supply voltage:

Make sure the flow meter is receiving the specified supply voltage. If an appropriately calibrated AC/DC multimeter indicates an incorrect supply voltage, immediately disconnect the device from the power supply and contact our technical support, as the electronics may have been damaged.

This value is an error message and usually means:

• The Pt 100 temperature sensor is not properly connected to the flow meter,
• defective Pt 100 temperature sensor,
• a break in the cable, or
• incorrect wiring.

Please refer to the user manual for information on proper wiring. Once the

connection, the temperature measurement will function properly again.

In most cases, the problem is not with the measuring device, but with the process conditions.

First, check the following points:

1. Is there actually flow?
2. Is the pipe completely filled?
3. Are the sensor spacing and alignment correct?
4. Are the signal and noise values within the permissible limits?

To do this, press <DISP> on the flow meter’s keypad to access the diagnostic level in the menu, and then press <NEXT> until the following values are displayed:

• Gain
• Signal
• Noise

The flow meter has these three preset limit values; under normal conditions, no measurement is possible outside these limits:

• If the signal drops below -10 dB, a valid measurement is not possible.
• If the noise rises above 10 dB, a valid measurement is not possible.
• If the SNR is < 6 dB, a valid measurement is not possible.

SNR (Signal-to-Noise Ratio) is the difference between the signal and the noise; for example, a 15 dB signal and -15 dB noise result in an SNR of 30 dB.

If a strong signal is displayed but no flow value is shown, the noise is often too high. In this case, check the sensor wiring for loose wires and consider grounding the cable shields.

Alternatively, you can make a note of the diagnostic values listed above and contact technical support if the problem persists.

For a reliable measurement, the signal must be at least -10 dB and the SNR must be at least 6 dB. If these values are not met, the following causes may be responsible:

Air pockets or a partially filled pipe

• If the pipe is empty or only partially filled, the flow meter cannot detect a sufficiently strong signal.

Heavily corroded or damaged pipe surface

• Rust, peeling paint, or a rough surface can interfere with signal transmission. Clean the measurement site and, if necessary, smooth the surface with a file, wire brush, sandpaper, or sander.

Inappropriate mounting position

• For horizontal pipes, the sensors should be mounted on the side, not at the top or bottom. For more information, see the manual, the quick start guide, or the installation videos.

Incorrect Sensor Alignment

• Install the sensors at the distance recommended by the Acoustic Sensor Positioning Wizard. The arrows engraved on the sensors must point in the direction of flow.

Insufficient coupling between the sensor and the pipe

• Apply a sufficient amount of coupling gel to the sensor surfaces. Air between the sensor and the pipe significantly weakens the signal.

High Gas or Solid Content in the Medium

• A high concentration of gases or solids can interfere with the measurement. Ensure that the medium is suitable for the measurement.

Incorrect sensor wiring (for permanently installed devices)

• Check the wiring according to the instructions in the manual.

Tip:

If the signal remains weak, reduce the number of sound paths to a maximum of one to maximize the available signal. If the problem persists, please contact technical support.

If the flow meter was operating continuously and the measurement suddenly stops, you should check the following:

1. Check the process conditions

• Is the liquid still flowing?
• Is the pipe completely full?

2. Check the sensor installation

• Check whether the sensors are still securely mounted on the pipe.
• Is there sensor coupling?
• Check the sensor connections and cables.

3. Check the settings in the menu

In the menu, open the item <System – Calibration – Zero – Zero Tracking> and ensure that Zero Tracking is set to <OFF>.

Also check the damping under <Output – Display – Damping>. For varying flow conditions, a damping time of approximately 5 s is recommended.

4. Account for temperature changes

Significant temperature fluctuations in the process can affect the measurement. If your process is subject to large temperature changes, using a Pt 100 temperature sensor may be advisable to compensate for temperature drifts.

Generally speaking, no. The measurement is based on the transit-time difference method and does not require factory calibration specific to the pipe. Once the application parameters (pipe diameter, pipe material, wall thickness, medium, etc.) have been entered, the accuracy specified above is achieved. An optional on-site process calibration can be performed if particularly high accuracy requirements exist.

A calibration certificate documents that the measurement system in use—consisting of an ultrasonic flowmeter and a pair of clamp-on sensors—provides measurement values within the specified accuracy range at various flow velocities. It is primarily used for quality assurance or regulatory documentation, but is not strictly required for regular operation. Calibration can be performed at the customer’s request for a fee.

No. Once installed correctly, the coupling remains stable over the long term. A visual inspection of the sensor wetting is recommended only under extreme environmental conditions, typically as part of an annual system inspection.

Inquiries regarding gas flow measurement are generally more complex than those involving liquid media and require a more thorough preliminary assessment. The main differences are:

Different types of waves

• Liquids: shear waves
• Gases: Lamb waves

Higher attenuation in gases

• Gases attenuate the signal significantly more. Therefore, a higher energy input is required to obtain a usable signal.

Limited Measurability

• While nearly all media can be measured in liquids, this is only possible to a limited extent with gases.

Dependence on Process Parameters

• The measurability of gases depends heavily on factors such as density, temperature, pressure, and composition.

Important:

For gas applications, it is therefore always necessary to conduct a preliminary feasibility assessment based on the application parameters—typically before a quote is provided.

Several application parameters are required to evaluate gas applications. These are critical for selecting a suitable measuring device.

Please provide the following information:

• Pipe material
• Pipe diameter
• Pipe wall thickness
• Medium / Gas composition
• Operating pressure
• Temperature
• Flow velocity

Note: 

The more complete this information is, the faster and more accurately we can assess feasibility and select a suitable device.