Buying guide for hydrostatic level sensors
What is the principle of hydrostatics?
Hydrostatics is a science that deals with the properties of vacuum, liquid and vapor.
This discipline relies on the action of the pressure exerted by the fluid on its surface to determine the heights or volumes involved.
The principle of hydrostatics was developed in the 16th century by an Italian mathematician named Evangelista Torricelli (1608-1647). It is one of the fundamental principles of hydraulics.
What is a hydrostatic level sensor?
Hydrostatic level sensors measure hydrostatic pressure, which is proportional to the measured liquid level.
Consisting of a pressure-measuring cell, the sensor's stainless steel or other diaphragm reacts to changes in level.
The force exerted by the diaphragm is converted by the level sensor into an analog electrical output signal.
How is hydrostatic level measurement calculated?
The relationship between the height h of the liquid and the hydrostatic pressure P in a liquid at rest and at atmospheric pressure, can be written as follows:
- g = 9.81 m/s 2 , constant, the Earth's acceleration due to gravity (at sea level) ;
- ρ = density of the liquid ;
- h = height of liquid.
The pressure measured by the transmitter is proportional to the liquid column. For example, for a water level measurement in a tank, the pressure varies by 100 mbar per meter of water column. For a tank height of 12 meters, the level sensor measures a pressure of 1.2 bar relative to the sensor diaphragm.
How does hydrostatic level measurement work?
Hydrostatic level measurement involves determining the height of a liquid using the hydrostatic pressure exerted by the liquid on its surface.
The higher the liquid level, the higher the measured pressure applied to the diaphragm. There are two different methods for measuring hydrostatic level.
Gauge pressure and differential pressure measurement methods.
A manometric pressure transmitter measures static pressure at a low position in the reservoir. This pressure is then converted into height using the hydrostatic level equation.
In closed vessels, a second measurement is required to measure the pressure of the gaseous atmosphere (air or gas above the liquid being measured). A differential pressure transmitter measures the differential pressure at two different points in the tank, where the tank is subjected to a pressure different from atmospheric pressure. The measuring cell calculates the pressure difference between these two points to determine the liquid level.
What are the applications of hydrostatic pressure transmitter level measurement?
For accurate hydrostatic level measurement, the specific weight of the product in the tank or reservoir and gravity must be taken into account.
Hydrostatic pressure transmitters are preferred for applications where the liquid density is constant.
Common industrial applications for hydrostatic pressure transmitter level measurement include the following:
Level control in tanks or pressure vessels- Level measurement in open-air or ventilated industrial tanks
- Level-dependent pump start-up and shutdown in open water and wastewater pipes
- Dosing and distribution of liquids in processes
- Automation of industrial level control processes and data transmission. These pressure transmitters are used in processes in the chemical and petrochemical industries (chemicals), the food industry (water, beverages, milk), the water industry (water and wastewater), the environment and theshipbuilding industry (seawater).
What are the advantages of hydrostatic level measurement?
Hydrostatic level probes use proven measurement technology and offer a number of advantages, including :
- Reliable, precise measurement
- Insensitive to foam and viscosity
- Independent of liquid dielectric constant
- Easy to install
- Works even with agitators
- Compatible with all internal tank structures
- Wide measuring range
- Long-term stability
What are the disadvantages of hydrostatic level measurement?
- The hydrostatic level sensor only works on liquids.
- Hydrostatic level transmitters offer measurement by contact with the fluids to be measured.
- Measurement is dependent on the density of the liquid to be measured and the pressure in the vessel.
- Regular maintenance is required to clean the sensor membrane of deposits and debris. Level measurement solutions with flush diaphragms or hygienic connections avoid the creation of retention zones.
- Intervention on level transmitters may require draining the reservoir. Level measurement systems with integrated ball valves do away with this constraint. Level probes can be removed without emptying the tank.
How to choose a hydrostatic level sensor?
To select a hydrostatic pressure transmitter , it is important to know the following parameters:
- the nature of the liquid (water, milk, oil, chemicals, etc.)
- product density
- process corrosiveness and abrasiveness
- liquid height (measurement range)
- type of tank (atmospheric or pressurized)
- reservoir pressure
- fluid temperature
- type of process connection (flanged, screwed, hygienic, etc.)
- local or remote display
- a protection index
The choice of level sensor will depend on these components. The scale of the sensor's measuring cell, and the materials of construction such as stainless steel, Hastelloy C and monel, all need to be adapted to ensure reliable, accurate measurement over time.
Fuji Electric solutions for liquid level measurement
Fuji Electric offers state-of-the-art hydrostatic pressure transmitters that meet the specific needs of different industries. These include the diaphragm seals pressure transmitter and the hydrostatic pressure transmitter .
Fuji Electric's diaphragm seals pressure transmitter is designed for accurate pressure measurement in harsh and corrosive environments. It offers excellent long-term stability, high resolution and accuracy, making it an ideal choice for demanding industrial applications.
Fuji Electric's hydrostatic pressure transmitter is specially designed for liquid level measurement. This sensor offers high precision, corrosion resistance and exceptional durabilityeven under extreme conditions.
These products offer advantages such as :
- Precise, reliable liquid level measurement
- Resistance to corrosive and harsh environments
- Long service life and low maintenance
Importance of hydrostatic pressure transmitters in industry
Hydrostatic pressure transmitters are essential to guarantee theefficiency and safety of industrial processes that require precise liquid level measurement. The solutions offered by Fuji Electric, such as the pressure transmitter with diaphragm sealsthe retractable level sensor and the pressure transmitter hydrostaticare reliable, technologically advanced tools that can be used in a variety of industries to solve common problems associated with liquid level measurement.
By choosing Fuji Electric as your trusted supplier for these essential products, you benefit not only from high-quality hydrostatic pressure transmitters , but also from a solid partnership and dedicated technical support to ensure the success of your projects.
LEVEL MEASUREMENT BY GAUGE PRESSURE
LEVEL MEASUREMENT DIFFERENTIAL PRESSURE