Specific gravity is a comparison ratio between the density of a particular substance and the density of a reference substance. Since the density of the reference substance will vary depending on its temperature, the specific gravity should also include the temperature of the reference media.
A very common reference media used for the calculation of specific gravity is fresh water at 4 degrees Celsius, which is very close to the temperature at which water is most dense.
The main use of specific gravity in pressure measurement is to calibrate hydrostatic liquid level measurement equipment. The majority of hydrostatic pressure measurement devices are calibrated in depth of water units such as mH2O or ftWG. Therefore if you want to use these devices to measure the level of a liquid which has a lower specific gravity than water, such as oil for example, you will need to re-calibrate the range from metres of water to meters of oil. The easiest way to do this is to divide the range in meters of water by the SG of the oil.
The calculation of specific gravity is very important to the management of liquid storage tanks, where the quantity of liquid contents has to be determined precisely for commercial purposes.
Borewell water level sensor for 100m water height
Underwater Pressure Sensors
200m deep well pump water level sensor, switch & display
Chemical Resistant Hydrostatic Liquid Level & Pressure Sensors
Glossary of Liquid Level technical terms
- Capacitive Fluid Level Measurement
- cmH2O – Centimetres of Water Column at 4 deg C Pressure Unit
- Conductive Fluid Level Detection
- Float Fluid Level Detection
- ftH2O – Feet of Water Column at 4 deg C Pressure Unit
- mH2O – Metres of Water Gauge at 4 deg C Pressure Unit
- mmH2O – Millimetres of Water Column at 4 deg C Pressure Unit
- Vibrating Tuning Fork Fluid Level Detection
Help from Liquid Level resources
- Measuring the volume of liquid in a horizontal cylinder tank
- Difference between vented and non-vented water level measurement
- Measuring liquid level in a tank using a dp sensor
- Determining water tank volume using hydrostatic pressure
- How do you measure the volume of a liquid using pressure
- Calculating required pressure range for fuel tank level measurement
