Figuring out how much the water level has risen or fallen in a tank (or something similar) should be a simple task. After all, it’s just basic math right? Sadly, the “real world” does not make measuring any liquid level that straightforward. Now, let’s be clear. Archimedes may not have used water displacement to tell the weight difference between silver and gold, but we can certainly measure the water level of anything with similar scientific principles.
Pressure transducers are an incredibly useful tool in discerning the fluid level in different bodies of water. It’s worth noting that water is not the only liquid that can be measured using a pressure transducer. Any liquid can be measured with a pressure transducer; that is, if the system is designed properly and requirements are met. Many households in the United States have a sump pump to monitor water levels. Granted, sump pumps do not use pressure transducers, but it helps to understand how common and vital measuring water levels are in everyday life.
How to Use a Pressure Transducer for Level Measurement
Measuring the level of any liquid can be accomplished if the proper considerations are taken into account. There are a few approaches that can be used to receive an accurate level measurement.
Bottom of the Water
The pressure transducer will be placed at the bottom of the body of water; it can be submerged or attached to the outside depending on the application. Once the pressure measurement is taken, it can be fed into the system. The system can use a few different formulas to calculate an estimate of the water level. The pressure above the water has to be taken into account with this level measurement method.
Granted, this approach will never be 100% accurate. It can give system engineers an idea of the current water level, however. This will allow systems to have the proper controls in place to alert system users to make the appropriate changes if the water level gets too high or too low.
Differential Pressure Transducer
In a water tank, simply measuring pressure at the bottom of the tank may not be accurate enough. Using a differential pressure transducer is more accurate than other methods for level measurement.
The differential pressure transducer has two legs that measure the pressure of both the bottom of the water as well as above the water. In this method the pressure transducer will be able to read the difference between the total pressure at the bottom of the water level and the gas pressure at the top. The water level can be easily calculated from this pressure reading.
Pressure transducers can produce quite a bit of meaningful data for researchers. They can even analyze the data to determine how water levels have changed in groundwater or river water. The data can be extremely valuable for environment researchers who are looking into rapidly changing bodies of water.
There are some other pressure transducer level measurement methods that are more complex. However, these are two of the most common measuring systems for basic applications. Some basic requirements that should be considered when selecting a pressure transducer are accuracy and sea water versus fresh water.
Sea Water vs. Fresh Water
Salinity can vary heavily across different bodies of water. For example, in the Dead Sea people can actually float because there is so much salt in the water. That might be fun for tourists, but attempting to design a pressure transducer that will function properly in that medium is a bit of a headache. Fresh water, on the other hand, is much easier to deal with. This type of water does not quickly degrade pressure transducers, like salt water does.
‘How accurate does my water level reading need to be?’ is one of the first questions that any engineer should ask. For example, water tanks in nuclear power plants are critically important to its operation. The pressure transducers must be incredibly accurate to ensure there are no meltdowns. The more accurate the pressure transducer, the more costly it will be. If your application does not require precise readings, your system may be able to get away with a less accurate pressure transducer.
Level measurement is not always a straightforward process for engineers -- even though it is critical in many applications. Pressure transducers can turn an impossible task into a walk in the park if you work with the right organization. Many manufacturers have the necessary experience to guide you in the right direction to measure your system’s liquid level.