V4 Sourcebook - March 2020

pH/ORP Sensors and Instruments Flow - Mou ting Overview

Mounting the Flow Sensor Inline

Installation of Flow Sensors:

1. Piping Location: The Correct location of the sensor in the piping system helps to ensure a proper flow profile in the pipe. It is important to have sufficient straight pipe immediately upstream of the sensor to create “fully developed turbulent flow.” Such a flow profile provides the stability required for the paddlewheel to measure accurately.

The diagrams below illustrate the minimum distances that are recommended to mount plastic and metal paddlewheel flow sensors.

In all scenarios, it is recommended to choose a location with as much straight, uninterrupted pipe length upstream of the sensor as possible.

2. Mounting Angle Paddlewheel sensors are affected by the mounting angle due to the effect of gravity increasing the friction between rotor and bearing surfaces. Air entrapment and sediments within the pipe may also adversely affect sensing accuracy and/or impede operation

Flow Sensor in Horizontal pipes:  45 deg from vertical is the recommended sensor mounting angle to avoid air bubbles (pipe must be full). With the sensor at greater angles, the drag created by the rotor resting against the sensor body may compromise performance at the lower end of the operating range.  Straight up installations may experience interference from entrained air at the top of the pipe.  Inverted installations are often subject to blockage due to sediments in the pipe. Mounting sensors in the bottom of the pipe is NOT recommended if sediments are likely to be in the pipe.

Flow Sensor in Vertical pipes:  Mount the sensor in a pipe with an upward flow. This position is recommended for all scenarios, as it ensures a full pipe.  Vertical installations with downward flow are not recommended.

194 PAAS Source Book

www.paas.com.au

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