Continuous measurement in a lift station can come from a variety of sensors including ultrasonic, radar, level probes, and submersible pressure transducers. Each sensor technology has pros and cons. Today’s post will focus on the benefits and challenges of using a submersible pressure transducer.
A pressure measurement at the bottom of a tank can be used to determine liquid. Submersible pressure sensors are specifically designed for these types of measurements. When a submersible pressure sensor is used in a lift station, it must be robust enough to deal with the turbulence and debris that is often present. For this purpose, a cage is often attached to the sensor to help protect the face of the transducer.
In addition, these sensors often include a “vent tube” with the cable. The vent tube is used to eliminate the impacts of ambient, or atmospheric, pressure outside of the well on the sensor reading, thus increasing the accuracy of the reading. By nature, all pressure instruments are differential pressure instruments, which either compare actual pressure to a fixed value (sealed) or a variable value, which in this case is atmospheric pressure.
Submersible pressure transducers are a very popular choice for continuous measurement in a lift station, and for good reason. Pressure sensor measurements are not effected by foam, vapor layers and physical obstructions that often cause problems for ultrasonic sensors, and they can be very easy to install. In addition, they are very cost competitive with other technologies.
The only real drawback to a submersible pressure transducer is that it gets submerged in a very nasty environment. Because of this, the idea of pulling that sensor for maintenance of any type is far from appetizing.
Not only is the material itself nasty, but when the pumps are running, some lift stations can have some pretty serious turbulence. Even with a cage installed, there is risk of the transducer face getting damaged and ruining the sensor. This is less of a concern with APG’s PT-500, which has a more robust transducer face than those found on many submersible pressure transducers.
It is for these reasons that some turn to ultrasonic and radar sensors, which we will discuss in an upcoming blog post.
Are you using submersible pressure sensors in your lift stations? If so, what do you like about using them and what problems do they create for you? Take a minute to look at the anatomy of APG’s submersible, which has some key advantages over competitor’s products.