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  3. D4. Correct positioning insertion flow meter

D4. Correct positioning insertion flow meter

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1. Introduction

In this chapter we will cover:

  • Positioning and tools for the right installation of your flow meter.

2. Positioning insertion flow meter

insertion_depth schematic

2.1 Insertion depth

A general rule of thumb:

Insertion depth: 0.5 * the inner pipe diameter.
The bottom of the sensor must be in the middle of the tube as seen in the picture.


Exception: Pipe sizes DN25 (1″) to DN65 (2.5″)

For these pipe sizes, measurements with an insertion type flow meter are possible:

  • Accuracy may be +/- 10% due to the larger blockage effect. (for higher accuracy take the VPFlowScope In-line flow meter).
  • Insertion depth is not in the middle, but 5 mm (0.2″) from the bottom of the pipe. This ensures proper temperature measurement.

Insertion depth table

2.2 Installation position

Install the flow meter upwards at an angle of 30 degrees. This way:

  • Easier access and visibility of the Transmitter / display.
  • Any drops (try to avoid them with thermal mass flow meters!) in the gas, will drip off without reaching the bottom of the probe.
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Never install upside down. Any dirt and moisture can stick easier on the sensor. It can also build up in the ball valve, creating unwanted oil/water showers and (electro) corrosion over time.

  • Even in the VPFlowScope DP water will enter the pressure sensing holes, causing misreadings or damage of the sensor.
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Flow direction indicators

For accurate measurements, it is important that the sensor is aligned correctly with the flow direction. Alignment by eye is sufficient.

There are 3 indicators to help you:

On the VPSensorCartridge:VPSensor flow indicator
On the safety system:Flow indicator on safety system
Via the sensor

3. Next Step

Now that you know all the information about how to position your flowmeter it is time to assemble and insert your flowmeter for fixed installation.

Next Step: D5. Assemble and install your insertion flow meter for fixed installation


Updated on May 11, 2020

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