The reasons for level measurement:
Safety: in boilers, a dangerous state can develop if the water level varies outside certain limits.
Economy : Good level control of solids is also desirable, excessive build up in hoppers can be expensive to clear.
Monitoring : Monitoring of level in bulk storage tanks and process vessels is necessary in order that:
- Plant efficiency may be assessed and optimized.
- Stock records may be kept.
- Cost may be correctly allocated.
In the oil and natural gas industries, Liquid level measurment is necessary to achieve the following objectives:
- Compute tank inventories of hydrocarbon liquid products and utility liquids.
2, Protect equipment such as columns, compressors, turbines and pumps from damage, - Protect operating and maintenance personnel against injury resulting from hydrocarbon, corrosive or toxic liquid spillage.
- Protect the environment from the release of objectionable liquids into the rivers and the sea.
- Control phase separation processes and product loading operations.
Unlike the pressure and temperature, liquid level has no absolute value and is always relative to some reference point such as the bottom of the tank. It is the height or depth of a liquid above a reference point and is specific to a particular vessel.