Staff gauges are among the most common ways to determine flow depth in a flume or a weir. This depth can then be used in the appropriate equation to measure flow rate with reliable accuracy. While these gauges are typically easy to use, some errors can arise due to improper application or maintenance. Learn all about the most common errors in staff gauge readings.
Improper Viewing Distance
A staff gauge is a physical measuring tool attached to the side of the flume or weir. This means you’ll have to look at it to see its reading, and there’s no digital display. Because of this, proper readings rely on what the human eye is capable of seeing. If the font is too small on the gauge, for example, you won’t be able to properly read it when you’re too far away. Choosing a staff gauge with contrasting colors between the increments/numbers and the background is a great way to enhance readability at further distances.
Misaligned Viewing Angle
The angle at which you view the staff gauge also plays a major role in accuracy. For example, you won’t be able to read the gauge properly if you’re looking down at it from above, which is the angle that’s typically the easiest to access. Surface turbulence can make that angle downright impossible to get a decent reading from. You’ll need to read measurements from an angle that’s level with the gauge. If such an angle is impossible, you may need a different method of measurement altogether.
Too Much Turbulence
Ideally, your flume or weir shouldn’t have much surface turbulence, as this can compromise all kinds of measurement methods. Staff gauges are no exception, as it’s difficult to tell the height of the flow by eye with turbulence. To counteract this, it’s best to install the staff gauge inside a stilling well. Even then, however, you have to make sure the stilling well is appropriately sized, or you’ll have to deal with well lag.
The cleanliness of your gauge will greatly impact your ability to read it. Even if you use one for a flume that’s largely self-cleaning, you’ll still need to make sure the gauge itself is clean as well. Staff gauges can gather debris from whatever is in the flow channel, like dirt, and they can also develop biological growth. Because of this, it’s always best to keep the gauge in a place that’s easily accessible for cleaning in addition to viewing.
Staff Gauges From Tracom
If you’re looking to avoid the common errors in staff gauge readings, Tracom is happy to help. While we also offer high-tech solutions, the tried and true staff gauge continues to prove its worth in terms of both function and cost. You can enjoy consistently accurate readings on your flume or weir with easy maintenance and virtually no installation costs whatsoever. Get in touch with our team today to learn more about our staff gauges as well as our custom flumes and weirs.