I have level data from a non-vented transducer in a water body and barometric pressure data from the same location. My elevation is 500 meters, how do I determine the true depth?
The true depth can be calculated by subtracting the actual atmospheric air pressure from absolute referenced level data.
Typically a non-vented depth transducer will have an absolute range, but this should be verified by checking the reading at zero depth, which should be around 10 mH20 or 1 bar, which would signify that the transducer does indeed have an absolute reference.
Featured non-vented reference hydrostatic level measurement products
Non-vented submersible absolute range pressure and barometric sensor for measuring 10m water level - Learn how to use a non-vented submersible sensor with a barometric pressure sensor for accurate water level measurement in challenging installations.
Seawater depth sensor with I2C output for aquaculture underwater camera integration - Compact OEM customised I²C pressure sensor with an Acetyl (Delrin) body and ceramic diaphragm providing a corrosion-proof solution for measuring depth in a subsea camera used for aquaculture.
If the reading is close to zero, it will most likely be a sealed gauge reference type instead, this means that it will have a fixed zero offset that will typically correspond 1 bar, which will need to be determined precisely by subtracting the zero depth reading from the actual atmospheric air pressure and then adding the result to all non-vented depth readings, e.g. if Zero depth = -50 mbar, Atmospheric pressure = 980 mbar, then 1030 mbar should be added to all the depth data to convert it to absolute readings.
If the barometric pressure is the actual pressure at that location without any meteorological adjustment for elevation you can simply subtract that reading from the absolute referenced level reading, but be careful to ensure all calculations are carried out in the same pressure units.
If the barometric pressure was obtained from a meteorological service or barometer it is most likely to be referenced to sea level and you will need to compensate it for the 500m elevation by using a barometric formula to calculate corrected pressure for elevation.
Featured barometric pressure measurement products
DMP331 Precision Pressure Transmitter - Stainless steel pressure transmitter with ranges from 100mbar up to 40 bar gauge or absolute. Special options for ATEX , SIL2 and compound ranges.
Marine approved atmospheric pressure sensor - Marine-approved pressure sensor for atmospheric pressure measurement on ships. 4-20mA output, 800-1200mbar range.
Related Help Guides
- Atmospheric pressure compensation for hydrostatic level sensors
- Difference between vented and non-vented water level measurement
- Using absolute pressure sensors to measure hydrostatic level
- Simulating 8000 foot altitude with a pressure gauge
- Measuring barometric pressure using a dp sensor
Related Technical Terms
- at – Technical Atmosphere Pressure Unit
- atm – Standard Atmosphere Pressure Unit
- Barometric Pressure
- inHg – Inches of Mercury at 0 degrees C Pressure Unit
- MSL – Mean Sea Level
Related Online Tools
- Gauge + Barometric to Absolute Pressure Calculator
- Suction Pressure to Vacuum Calculator
- US Standard Atmosphere Altitude and Pressure Calculator
- ICAO Standard Atmosphere Altitude and Pressure Calculator
- Elevation, Station (QFE) and Sea Level (QNH) Pressure Calculator
