Description: A submersible pressure transducer is a contact water level sensor that measures the head of water above the sensor through the pressure exerted on the sensor head. Components are relatively simple and low cost. The sensor and cable are often placed in pipe/conduit that provided a limited degree of protection. There are two types of pressure transducers, being vented and non-vented. The vented option, has a tube that allows ambient air pressure to be measured by the transducer. The vented systems are then able to subtrct the atmospheric pressure from the static head pressure, thus removing variability due to changes of atmospheric air pressure on the measurement of water level. Vented solutions often require desiccant to keep the transducer free from moisture. The desiccant needs to be changed occassionaly (more often when dew point temperature is high), which can be a maintenance concern. Non-vented pressure transducers operate without directly compensating to atmospheric air pressure. Non-vented sensor or usually less expensive, require less maintenance, along with being less accurate. A third type of pressure transducer is a vented system, but the vented pressure measures the pressure from a bellows system. This solution does not require desiccant, but it generally less accurate than the vented systems to the atmosphere. The submersible pressure transducer is most common in ground water wells. Though the submersible transducers are often used in river systems because of the low initial cost, the threat of having the sensor damaged by flood waters and debris make it a less than optional solution for natural river courses.
Operational range of the sensor may vary from 0 to 350m. It is important to select the full-scale range that closely meets your needs. Accuracy is typically based on a percentage of full scale value, therefore the smaller the range the higher accuracy the measurement will be. It is important to not select a sensor range that is smaller than the maximum water level, this could cause damage to the sensor
Costs USD Lower: $500
Costs USD Upper: $1,500
Accessories: Desiccant, staff gauge
Advantages: Easy to install and relatively inexpensive. Some submersible pressure transducers offer internal data logging and power supply
Disadvantages: Susceptible to damage from water pollution and being fouled by sediment. Like any 'in stream"" measurement system, the pipe holding the pressure transducer is susceptible to damage by high water, and objects being carried by high water. In the event the sensor is lost/damaged, the expense of replacement if higher than most other solutions. Sensor needs occasional calibration to check the instrument linearity. Best suited for ground water measurement within a borehole
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