Weir Cleaning For Most Accurate Flow Readings

While flumes are largely self-cleaning, you’ll have to go a bit further when it comes to maintaining a weir. Weirs require regular inspections and cleaning if you want to maintain accurate flow measurements. Fortunately, the process is relatively simple. Learn everything you need to know about how to clean a weir and ensure your weir stays in top shape for as long as you need it.

Upstream Conditions

The upstream conditions of a weir greatly impact the functioning of the weir, so you have to make a concentrated effort to keep them clean. Due to the damming action of the weir, solids will eventually build up in the upstream weir pool. In order for the flow rate to be regulated, however, the weir pool must be completely free of obstructions.

To ensure your weir pool stays free and clear of obstructions, you’ll need to clean the surrounding area. Weeds and other vegetation can compromise your weir pool, so trimming them back is the best way to keep them out of the weir pool. This also includes trees that could be hanging over the stream and potentially dropping in branches and other debris. Remember, the general rule is that the pool’s invert measures twice the maximum head below the crest at least.

The Weir Itself

The first thing you should do when cleaning a weir is to inspect for leakage around the structure itself. Any leaks could lead to a major point by which the flow undercuts the weir, defeating the entire purpose of the installation. It’s especially important to keep an eye out for leaks if you utilize clean-out doors. While these doors are useful in sluicing sand deposits, they can allow flow to move right past the weir, throwing off your measurements.

Additionally, you’ll want to make sure your weir is plumb and level. A recent installation done correctly will already have your weir set up like that, but weir systems can shift over time. Always measure during an inspection to see if any adjustments need to be made to ensure it doesn’t lean in any one direction. Keep in mind that this may require an alteration of the foundation.

The Weir Crest

The crest of the weir is key to functional operation, so it’s always best to take extra care of this essential piece. While the shape of the weir and the nature of the flow affect exactly how often the crest needs to be inspected and cleaned, it’s always necessary to maintain a proper schedule. For example, V-notch weirs will need to be cleaned more often than rectangular weirs. As you might expect, high-solids flows will need more frequent cleaning as well.

It’s best to maintain a checklist when it comes to weir crest maintenance. The following are the most important factors to look out for during your inspection and maintenance process:

  • General wear and damage.
  • Rounding.
  • Obstructions.
  • Oil buildup.
  • Level.
  • Relation to upstream gauge zero.

Weir Boxes From Tracom

You know how to clean a weir, but that can only go so far if your system is aging. Whether you’re looking to simply replace your system or start a new one, Tracom is happy to help. We’re the No. 1 choice for customized weir boxes that are built for accurate measurements and come complete for installation. Contact us today to learn more.

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