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How to Maintain a Weir Box

Although simple devices, Weirs Boxes do require periodic maintenance to provide accurate flow measurement.


  • Inspect the weir pool floor, removing sediment and debris as necessary

  • Verify that the crest is horizontally and vertically level.

  • Verify that the crest is at least 2 Hmax above the maximum downstream water level.

  • Clean the crest of any debris, ragging, vegetative growth, etc.

  • Inspect the weir crest for nicks, burrs, rust, ice, or any other condition that affects flow over it.

  • Verify that the zero elevation at the point of measurement is the same as the bottom of the weir crest.

  • Inspect the weir plate / carrier for signs of leakage.  While the weir plate / carrier are factory sealed, the stresses of shipment and installation may require that additional sealing be conducted after the weir box has been installed.

  • Inspect the inlet and outlet end connections for signs of leakage.

Downstream CHANNEL

  • If the discharge is free-spilling, inspect the downstream channel for signs of scour – reinforcing the channel as necessary.

  • Remove any debris, growth, etc. which may impede flow through the downstream channel.