What instrument should be used to measure levels in a lift station?
asked 18 June 2015 asked by juan29 (1080 points)
Hi, radar instruments are very reliable and precise. A good trade-off even for deep lift stations. However watch out for thick accumulations of foam which can disrupt the reading. VEGA makes a good product.
I can confirm that VEGA works well. You can link it directly to the control panel without an intermediate transmitter.
Hello, Yes, these remotely powered sensors can be added directly to a local station; the transmitter is handy for setting the sensor parameters (which has to be done on installation) or when you need output relays or to view local data like curves, echo ..
I also confirm that radar technology is reliable and better adapted than the ultrasonic "aerial" sensor. But a little more expensive. Piezo sensors installed and immersed in a PVC tube also give very good results.
Most of our customers use piezo (hydrostatic) level sensor because they're a no-brainer. Radar as previously mentioned works fine and has the advantage of being a non-contact instruments. But sometimes they are a little trickier to install properly and the operators lacks the knowledge to do a proper start-up with mapping and other envelop-curve filters. But the #1 downside is even with a proper mapping to eliminate the echo coming from a ladder or a pump chain, the fat content or other junk can attach to an obstacle changing the "image" seen by the radar. You need to use models with advanced functions like Dynamic Mapping and usually, municipalities tend to go for lower-end models who don't offer these functions.
Hi, you can also use a piezo sensor. It all depends on your budget.
I recommend you place the piezo sensor in a disposable glove filled with water and closed to prevent contamination by any fats or sand.
We also tried the glove, but ... a piece of bike inner tube without any puncture of course (filled with water) with 2 stainless steel clamps and PVC cap on one end lasts for a while and no worries ..
If we asked the supplier to replace the glove or an air chamber, we might get them to improve the product? Alain
The additional cost of buying the piezometric sensor is offset by preventing malfunctions (especially because of accumulated foam and fats). We have kept a high level alarm float (just before the o/f). It may be a bit primitive but it’s a guarantee against sensor failure.
Hello. The float switch is the most commonly used device. If a sensor is installed for regular operations, a float switch is wired as a backup.
Hello, backup with a float switch is still necessary, or at least one high float to switch on and a low one to switch off, and one at a very high level alarm; this means the lift station can continue to work even if the sensor fails.
The Vega radar sensor works well. I tested the Paratronic radar sensor. It has the advantage being easy to install. Attached with an automatic level switch as soon as the lower seal is removed. Moreover its total height is much less than the Vega. (Ideal for o/f structure, for example)
Hi, you can always use the VEGABAR 86 suspension pressure transmitter, monitor it for fouling, or insert the sensor into a PVC tube for added protection .
You might experience the same behavior going to a radar. The problem is indeed the level fluctuation + grease. Your Time of Flight device (ultrasound or radar) was probably set with a mapping. This is a fixed "picture" of the obstacles at a certain time. As the level varies, grease attaches itself to some obstacles. This grease absorbs the energy from your US wave. Another behavior you could get is false level readings. This come from the energy being reflected off a new obstacles like grease or other junk that sticks to something which modifies the original mapping and is now perceived as the level. A hint for this is that in reality, the level goes down but the instrument is stuck at a fixed value.