What is an Inline Style Flow Meter, its Benefits, and Common Uses?

Inline style flow meters
Physical Description of Inline Style Flow Meters

Local inline style flow meters have an electronics enclosure connected to a probe that is pre-installed in a section of pipe called a flow body. The flow body may be equipped with different process connections like NPT ends or flanges. NPT ends are commonly used in applications with smaller pipe sizes (up to 3-inch). Flanged end connections are routinely used for larger pipe sizes and in applications where threaded connections are not viable.

The flow body size should match the pipe size to which it is being connected. This ensures that there is not a pressure drop that may affect process function or the accuracy of the flow meter.

Fox Thermal flow meters are equipped with enclosures that have various approval ratings for use in explosive environments. A comparison of product approvals, styles, and features for Fox Thermal products can be viewed on our Products page and a full list of certification and approval documentation can be viewed on our Certifications page.

Advantages of an Inline Flow Meter

There are many factors that influence a user’s decision on what style of flow meter is required for a particular application. There may be pressure considerations, the possibility for corrosion, or physical limitations to the available process pipes. Fox Thermal inline flowbodies are available in standard stainless-steel construction with options for carbon steel.

The advantages of an Inline flow meter are:

  • Built-in flow conditioning
  • Fewer straight run requirements than an insertion style
  • Factory-configured depth setting of probe/sensor ensuring measurement accuracy

Straight run requirements for Inline flow meters
Straight Run Requirements of Inline Flow Meters and Built-in Flow Conditioning

Lateral placement of the inline flow meter on the process pipe is determined by the straight run requirements of the style of flow meter and the location of obstructions or elbows in the pipe that create swirl or turbulent flow profiles. For more accurate flow measurement, a uniform flow profile is preferred. This can be achieved either through the addition of straight pipe runs between the causes of turbulent flow or through the addition of a flow conditioning device. As Fox inline flow meters are constructed with built-in flow conditioners, the straight run requirements are less than insertion style flow meters.

Fox Thermal recommends that inline style flow meters have at least 8 diameters of straight, unobstructed pipe lengths upstream and 4 downstream.

Remote Inline style flow meter
Remote Inline Style Flow Meters

Remote inline style flow meters have an electronics enclosure that can be mounted away from the flow body. The enclosure is connected by cable to a remote junction box fitted to the probe and flow body assembly. A remote style inline flow meter is needed in cases where the flow body installation location would make viewing the flow meter’s display difficult for the user.

Installation of an Inline Flow Meter

The lateral placement of the flow meter must first be determined according to the upstream and downstream straight pipe requirements for inline flow meters. Installation requires that a section of pipe be removed at the insertion point on the process pipe to accommodate the installation of the flow body. The flow meter’s sensing elements are pre-aligned with the flow body’s centerline to ensure the most accurate measurement of the process gas in the pipe.

Fox Thermal flow meters are programmed at the factory to be ready to operate immediately after the installation and wiring steps have been completed. See your model’s instruction manual for details on these steps.

Talk to an Expert

To get expert help on your flow measurement application, contact one of our Application Engineers or find a rep near you!

Answer a few questions in our useful online Help me Choose Tool to get a recommended flow meter type right away! Then use our Product Configurator to get the right flow meter built to your specific process conditions.

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