0191 5131313 | hello@siris.co.uk
0191 5131313 | hello@siris.co.uk

What is flow monitoring?

Flow monitoring is used for many reasons including system control and regulatory purposes. Flow monitoring can be carried out throughout a variety of means to establish a flow rate.


Primary and Secondary Devices in a Flow System 

In order to set up a flow system you have to set up both a primary and secondary device.

Primary device examples include V-notch, rectangular weir or flume, the secondary device is the flow metre that is associated with either option.

V-Notch Weirs

  • Typically used on final effluent, not to be used on inlets. 
  • Used when flow rate is quite low, 5-10L per second. 
  • Secondary devices could be an ultrasonic sensor or a radar. Radars do not need a sun shield as their readings are not affected by temperature.
Issues we find with V-notch weirs
  1. Insufficient Maintenance 
  2. Incorrect sensor positioning 
  3. No sun shade for ultrasonic sensors 
  4. Inaccurate flow calculations during set-up 
  5. Turbulence and Foaming


Typically seen on inlet but can also be used on final effluent if good hydraulics are apparent.


Issues we find with flumes
  1. Insufficient Maintenance 
  2. Incorrect Flume Sizing 
  3. Unsuitable approach conditions 

Magnetic Flow Meters

Can be used on both pump lines and gravity lines.


Issues we find with MAG Meters
  1. Installation too close to another meter
  2. Incorrect use with partial flow
  3. Insufficient Maintenance 
  4. Insufficient Approach 
  5. Incorrect Sizing