Standards

It is now necessary to protect sensitive sites upstream and downstream of networks.

Article 92-3 of the French Water Act of 3 January 1992 makes it mandatory to:

  • Controlling rainwater and run-off
  • Flood protection
  • Pollution control.

Several parameters need to be taken into account when regulating flow:

  • The constancy of the leakage flow: Fascicule 77-284 (the technical instruction relating to urban drainage networks) states that a flow can be considered ‘constant if it does not vary by more than 10% as a function of the head of water’.
  • The intake surface of the incoming flow: For the same flow rate and head of water, a traditional nozzle (e.g. a pipe) will have an intake surface area 2 to 3 times smaller than a flow regulator or controller, increasing the risk of clogging and, consequently, flooding.
  • Device maintenance: Devices with moving parts should be avoided in wastewater systems.
Motifs décoratifs pour les contenus

The operating principle

By increasing the hydraulic head upstream, and thanks to a given angle, the supply to the controller creates a swirling current, known as the vortex effect, with the formation of a core of air. The pressure losses generated by this process limit the flow while maintaining a constant cross-sectional area, 2 to 3 times greater than that of a nozzle.

Dimensions

The sizing of a flow controller depends on the following parameters:

  • Diameter and slope of downstream pipe
  • Maximum head of water in the structure
  • Expected leakage rate.

When establishing the range, a step size of 0.5 m was used for the head of water in order to establish a pricing system. However, during the construction phase, this approach is no longer sufficient and generates significant differences in the leakage rate if the product is not adapted to the site surveys.