Keyence Launches new FD-H Series of Clamp-On Fluid Flow Sensors

April 07, 2022 by Damond Goodwin

New non-obstructive sensor series adapts to a wider variety of piping materials, providing accurate data with lower influence from viscosity and bubbles.

Keyence is a world leader in flow metering systems and sensors. They have recently developed a new clamp-on style system capable of monitoring flow without the challenges of the in-line installation methods. The system is capable of monitoring flow in rigid as well as flexible piping systems and offers expandable options for temperature and liquid concentration.


Keyence FD-H sensor

Keyence announces new FD-H series of clamp-on flow sensors Image used courtesy of Keyence


Challenges with Flow Measurement

Traditional in-line flow measurement has several downfalls that the new Keyence sensor circumvents. Most flow meters need direct interaction with the liquid in order to measure flow rate. In order to do this, the pipe or hose carrying the liquid has to be compromised in some way. Generally, the pipe has to be cut and fittings inserted to accept a traditional flow meter. This creates additional places for the possibility of developing leaks.

The addition of those in-line flowmeters will require the system to be shut for pipe cutting and fitting insertion, creating downtime for the plant. Since this type of flowmeter is invasive, it creates a pressure drop because of the direct interaction with the liquid and restricting flow.

Of course, it should go without saying that a large number of in-line flowmeter technologies exist, some more invasive than others. One of the oldest traditional technologies is shown below - the rotameter - but modern in-line methods include LED and ultrasonic technology, reducing pressure dropping restrictions for more efficient processes.



Rotameter - accurate, reliable, and a great choice for simple systems where digital connections may not be required. Image used courtesy of Instrumart


Flowrate sensors that clamp to pipes have existed for some time, but the technology continues to evolve to create more accurate sensing capabilities, enhanced pipe material compatibility, and methods of sensing that work in more environments to minimize flow restrictions.

Keyence FD-H Series Clamp-on Meters

Keyence Clamp-on flow sensors simply attach around the pipe without any need for pipe modification. This has several advantages over more traditional methods. Since the pipe is unchanged, flow is relatively unobstructed (all sensing methods to date still disturb flow to some small extent) and there are fewer points for leaks to develop. The device is capable of measuring:

  • Water
  • DI water
  • Oil
  • Chemicals
  • Coolants

The clamp-on meter is remarkably forgiving and will tolerate bubbles, high temperatures, and highly viscous liquids. It has an accuracy of 3% and has a built-in diagnostic function. With the addition of a concentration sensor and temperature sensor, process and product quality more accurately monitored and predicted.

There are 10 different models capable of measurement ranges from 20 liters per minute for smaller applications to 500 liters per minute for larger applications. The FD-H system is capable of measuring liquid flow, and additional Keyence sensors provide accurate concentration and temperature monitoring.

Keyence has made the flow meter connectable via I/O link as well as discrete limit and analog outputs to give customers more flexibility when integrating into plant infrastructure. It comes standard with IP66 or IP67 ratings for installation environment consideration.


Keyence flow data

Data view and trending are simple on the removable display of the FD-H flow sensor. Image used courtesy of Keyence


The meter has a built-in display capable of showing real-time values. The display is not only large and easy to read but is also detachable, communicating with the sensor wirelessly for remote monitoring and diagnostics. The historical data trending function can be quite useful for troubleshooting or looking back on how the system has been operating over time. With real-time graphing customers can see a visual representation of shorter-term data trends and predictions.


Keyence has helped to reduce costs and simplify how liquids are monitored. Their system is non-invasive and has the ability to measure many different liquids of varying viscosity with a high level of accuracy. The meter simply clamps to the pipe or hose carrying the liquid to be measured, helping to reduce or eliminate the need for downtime when it is added to an operating system. It can be used on any type of pipe or hose including metal, plastic and rubber pipes, or any type of hose. With the addition of the FD-H system, customers can measure flow, temperature, and liquid concentrations.