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

Insertion style flow meters
Physical Description of Insertion Style Flow Meters

Local insertion style flow meters have an enclosure housing the electronics of the flow meter intrinsically connected to a probe that is inserted into the process pipe. The length of the probe is determined by pipe size and any additional clearance needed above the process pipe due to insulation or other piping/equipment.

All Fox Thermal flow meter models are available in insertion styles. There are many available probe lengths that can accommodate line sizes from 1.5-inches up to 70-inches. Insertion style flow meters can be installed in horizontal or vertical pipes.

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 Insertion 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 probes are available in standard stainless-steel construction with options for high temperature or Hastelloy C276 sensor types.

The advantages of an insertion flow meter are:

  • Ease of installation
  • Faster lead times
  • Appealing price point
  • Suitable for larger pipe/duct sizes (up to 70-inch)
  • Allows for retractor/ball-valve option to remove and reinstall meter from active processes

Straight run requirements for insertion flow meters
Straight Run Requirements of Insertion Flow Meters

Lateral placement of the flow meter on the process pipe is determined by the straight run requirements of the style of flow meter and the existence 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.

Fox Thermal recommends that insertion style flow meters have at least 15 diameters of straight, unobstructed pipe lengths upstream and 10 downstream of the insertion point.

FC20 flow conditioner
Flow Conditioning with an Insertion Flow Meter

Fox Thermal developed the FC20 flow conditioner that allows users some flexibility with the straight run requirements of insertion style flow meters. Use of the FC20 reduces straight run requirements by 7 pipe inside diameters (IDs) upstream and 6 pipe IDs downstream. This is especially useful in process equipment with limited straight pipe runs available at the installation site.

The FC20 can be installed upstream of the insertion probe installation point to correct distortion and swirl disturbances to the flow profile of the process gas. This results in a uniform flow profile necessary for accurate flow measurement from the sensing elements in the probe. For more information on the FC20 Flow Conditioner, visit our FC20 Product Page.

Remote insertion style flow meter
Remote Style Insertion Flow Meters

Remote style insertion flow meters have an enclosure that can be mounted at a distance away from the probe. The enclosure is connected by cable to a remote junction box fitted to the probe. A remote style insertion flow meter is needed in cases where the probe insertion location would make viewing the flow meter’s display difficult for the user if an intrinsic insertion flow meter were used.

The advantages of a remote mounted insertion flow meter are:

  • Convenient location of the electronics display for easy viewing
  • Quick access to settings through the flow meter’s configuration panel*
  • Easy access to USB port* to connect a PC or laptop and launch FT View™ software
  • Better access to electronics wiring

*Option availability dependent on model type

Insertion meters with retractors
Retractors Used with Insertion Flow Meters and their Benefits

Equipped with a ball valve, retractors are optional mounting hardware that allow the user to safely “retract” the flow meter’s probe out of the process stream, valve off the flow of process gas at the insertion point, and gain access to the flow meter for maintenance such as cleaning, servicing, or relocating the flow meter. The benefits of retractors are:

The benefits of retractors are:

  • Access to the flow meter’s probe without the need to shut down the process
  • Quick and easy re-insertion of the flow meter to the appropriate depth setting

Installation of an Insertion Flow Meter

After the lateral placement has been determined, installation requires a female NPT fitting to be welded to the insertion point on the process pipe and a hole drilled to allow the flow meter probe to be inserted through one wall of the pipe and into the process stream.

The probe’s sensing elements must be properly aligned with the pipe’s centerline to ensure the most accurate measurement of the process gas in the pipe. A formula (varies per model type, see product instruction manual for details) helps the installer measure the proper depth setting to achieve the optimal placement of the sensing elements in the process pipe. Once the proper depth has been formulated and the alignment of the probe in the direction of flow, the flow meter is secured in place with a compression fitting.

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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