How to measure level of a pond/lagoon

[texansurfer 0]

a client wants to measure level of an existing discharge pond. it is about 40-50 ft deep so ultrasonic would be a good option. the pond is currently full. can you please suggest which sensor/transmitter would be ideal to measure the level? transmitter will be connected to a micro plc. thanks..

[DanW 41]

Two technologies: 1) Head pressure with a submersible pressure transmitter. Sensor head comes with a long coil of cable and a vent tube. Sensor is dropped into the pond and it rests on or near the bottom. The head pressure of the water above it produces a 4-20mA output signal. The measurement is the water level over the transmitter. It is powered with a 24Vdc power supply (industry standard). The 4-20mA can go long distances over copper wire. Somewhat vandal resistant because the cable on the shore can be run in conduit to a panel on pole, with the sensor in/under the water. 2) Ultrasonic level. An ultrasonic level is mounted on a stationary fixture a couple feet (600mm) above highest level conceiveable. The sensor generates an ultrasonic piug that bounces off the water/floating debris/ice and is converted to level (assuming some arbitrary zero at some depth) or distance, the distance from the stationary transducer) and provided as a 4-20mA signal. The instrument is usually AC powered, but can be had with DC power that can run from battery/solar, particularly if the update is in frequent, like hourly or twice a day. This technique is also used extensively over a flow weir where the level is used to calculate flow rate. The PLC would need an analog input compatible with the 4-20mA output of the sensor.

[waterboy 7]

A bubbler style pressure probe could be used if there is a chance of silt fouling the pressure transmitter. Old school, old tech, but they work. If the pond is fairly clean then I would prefer a pressure probe.

[JeffKiper 9]

Look at In-situ.com