What is hydrostatic pressure?
Hydrostatic pressure is the pressure exerted by a stationary fluid due to the effect of gravity. It increases with the depth of the fluid.
Hydrostatic pressure is widely used in engineering. Especially when designing structures that will be subjected to liquid loads. For example, the design of pipes within a house or other building needs to take hydrostatic pressure into account. This is to ensure that the pipes can safely withstand the liquid load. If the pipes cannot withstand the liquid load, it may burst.
Characteristics of hydrostatic pressure include:
- All-around action;
- Hydrostatic pressure is applied evenly to all parts of the surface of an object;
- Pressure increases with depth;
- The deeper the liquid is, the greater the pressure applied;
- Dependent on liquid density and depth;
- Hydrostatic pressure is a function of the density and depth of the liquid and the gravitational constant and is independent of the shape and mass of the liquid.
What is a hydrostatic pressure sensor?
Hydrostatic pressure sensors are specially designed to directly measure the pressure of liquid at a certain depth. Using the principle of hydrostatic pressure, the depth of liquid can be measured indirectly.
A hydrostatic pressure sensor measurement can be made with a submersible-mounted probe. Or the pressure sensor can be installed as close to the bottom of the tank as possible. It is widely used in many industries such as measuring the pressure of liquids in tanks or reservoirs, food, water, and wastewater.
Key points about hydrostatic pressure sensors:
Function: They measure the static pressure of a column of liquid. This static pressure is proportional to the liquid level.
Design: Usually a submersible pressure transmitter. Its diaphragm is exposed to the liquid. The pressure difference across the diaphragm is converted into an electrical signal.
Key principle: Hydrostatic pressure is directly related to the density of the liquid and the depth of the sensor.
Working principle of hydrostatic pressure sensor
The working principle of the hydrostatic pressure sensor is to measure the pressure exerted by a liquid column at a given depth. The pressure is proportional to the height of the liquid column. The liquid level is calculated based on the principle that the pressure increases with the depth of the liquid due to weight and gravity. By sensing the change in the static pressure of the liquid, it is converted into an electrical signal. After temperature compensation and linear correction, it finally outputs a standard electrical signal (usually 4~20mA or 1~5VDC).
The basic principle of a hydrostatic pressure sensor is based on the principle of hydrostatic pressure measurement:
This principle is based on Pascal’s law. This law states that pressure applied to a confined fluid is transmitted evenly in all directions throughout the fluid. The pressure exerted by a stationary fluid at a certain point is proportional to the depth of the liquid column above that point. It is calculated based on the density of the fluid, the acceleration due to gravity, and the depth. The deeper you are in the fluid, the greater the pressure exerted due to the weight of the fluid above.
Hydrostatic Pressure Formula
The measurement formula of hydrostatic pressure is: P = ρ*g*d,
where:
- P represents hydrostatic pressure, in Pascal (Pa);
- ρ represents the density of the fluid, in kilograms per cubic meter (kg/m³);
- g represents the acceleration due to gravity, usually 9.8 m/s²;
- h represents the height of the fluid, in meters (m).
Example Calculation
We can demonstrate this with an example. Suppose we have a swimming pool that is 10 meters deep and filled with water (ρ = 1000 kg/m³). Let’s calculate the pressure at the bottom of the pool. Using the hydrostatic pressure formula:
- ρ = 1000 kg/m³
- g = 9.81 m/s² (standard value of gravity)
- h = 10 m
Substituting these values into the formula we get:
P = ρgh • P = (1000 kg/m³) * (9.81 m/s²) * (10 m) • P = 98,100 Pa (Pascals)
So, the pressure at the bottom of the swimming pool is 98,100 Pascals (Pa).
Application of hydrostatic pressure sensors
Hydrostatic pressure sensors have a wide range of applications in a variety of fields. They are able to measure pressure which is directly related to the depth of the liquid.
Main applications of hydrostatic pressure sensors:
- Industrial Tank Level Monitoring: Measure the level of liquid in oil, chemical, and water storage tanks. To control inventory and prevent overflows.
- Wastewater Treatment Plants: Monitor levels at various stages of the treatment process.
- Well Water Monitoring: Measure groundwater levels in wells.
- Pool Level Control: Maintain the desired water level in swimming pools.
- Marine Applications: Measure water depth for navigation and offshore operations.
- HVAC Systems: Monitor pressure in heating and cooling systems to ensure efficient operation.
- Automotive Applications: Tire Pressure Monitoring Systems.
- Medical Devices: Blood pressure measurement in medical devices.
- Aerospace Applications: Use air pressure to measure aircraft altitude.
Advantages of hydrostatic pressure sensor
Hydrostatic pressure sensors have many advantages, including high reliability, accurate level measurement, insensitivity to foam and viscosity, and easy installation. They can work properly even in turbulent or contaminated liquids. They are very suitable for applications such as tank level monitoring in harsh environments.
Main advantages of hydrostatic pressure sensors:
- High accuracy: Hydrostatic pressure sensors are usually highly accurate. They can accurately measure small pressure changes.
- Insensitive to foam and turbulence: Unlike other liquid level sensors. Hydrostatic pressure sensors are not significantly affected by foam or agitation in the liquid.
- Stability: High-quality hydrostatic pressure sensors are not affected by factors such as temperature and humidity.
- Durability: Hydrostatic pressure sensors are made of corrosion-resistant materials. They can work for a long time in harsh industrial environments without damage.
- Easy to integrate: Hydrostatic pressure sensors can be easily integrated into various systems. Such as automated control systems, monitoring systems, etc., to provide real-time data.
- Low energy consumption: Many hydrostatic pressure sensors are designed with low energy consumption. Suitable for long-term continuous operation and reduce energy consumption.
- Environmental adaptability: Hydrostatic pressure sensors can be designed to be suitable for different media and environments. Including high temperature, high pressure, corrosive environment, etc.
- Easy to maintain: Due to its simple structure, hydrostatic pressure sensors are usually easy to maintain and replace. Reduce long-term operating costs.
More pressure and level measurement solutions
Each solution offers unique capabilities for different applications and environments based on factors such as pressure range, temperature, fluid type, and required accuracy.
Specific examples of advanced pressure and level measurement solutions:
- Guided wave radar: For high-pressure applications, including liquids with high dielectric constants.
- Ultrasonic level sensors: Can measure the level of open tanks or those with large vapor spaces.
- Magnetostrictive level transmitters: Offer high accuracy and are often used in tanks with agitators.
- Differential pressure transmitters with diaphragm seals: Ideal for measuring the level of corrosive or viscous fluids.
- Capacitive level sensors: Used to monitor the interface level between different liquids.
- Weighing systems: Provide high accuracy level measurement when combined with tanks or containers.
Hydrostatic pressure transmitters measure the pressure of a stationary liquid. And use this measurement to determine the height of the liquid. They are used in a variety of applications. Including water tanks, pump wells and sewage treatment plants. When choosing a hydrostatic pressure transmitter, there are many factors to consider: pressure range, accuracy, media compatibility, etc.
Compared with other level measurement technologies, whether it is a submersible hydrostatic level transmitter or a pressure or differential pressure level transmitter. The cost of hydrostatic level measurement is relatively low.
We are a professional hydrostatic level sensor manufacturer at Sino-Inst. We also provide a variety of customized pressure sensors, level gauges, etc. If you need hydrostatic level measurement or related technical information, please feel free to contact us.
