Hydrostatic Level Gauge (Level Sensor)

Hydrostatic Level Measurement

The hydrostatic level gauge operates by measuring the pressure or pressure difference in a liquid. This method is based on the fact of the existence of hydrostatic pressure in a liquid and its change directly proportional to the depth. Special sensors allow measuring the level in open or closed tanks. Accordingly, one membrane is installed directly on the tank, and the other – in the area of excess pressure (for closed containers) and at the supply of atmospheric pressure (in open ones). Devices of this type can work with viscous liquids and under high excess pressure. However, it is important that the sensitive element is in direct contact with the measured medium.

Hydraulic type level sensors are made in two design variants.

Hydrostatic Probe

The first design option is submersible pressure transducers, which consist of 2 units connected by a compensation cable. The measuring unit is a submersible probe. They are used for wells, pits, open tanks, reservoirs. Also suitable for non-pressurized tanks. Devices are made from various materials. The housing can be stainless steel or polymer, and the sensitive membrane – steel or ceramic. Inside the compensation cable sheath runs a reference pressure tube, which can be made of Teflon, polyurethane, or PVC.

Flanged Level Transducer

The second option is a flanged transducer suitable for horizontal installation in the tank wall. They feature an open end membrane. Models can also be contact or non-contact.

Models are also classified by:

• Connection method: submersible, flanged, flange-mounted;
• Type of measured medium: non-aggressive or aggressive, viscous, abrasive, and so on;
• Atmospheric connection method: for closed and open tanks.

Application Area of Hydrostatic Level Sensor

Hydrostatic level sensors are optimized functional devices that help measure the depth of the liquid column and pressure. They are used in various industries related to water or gas, including oil and gas, chemical, pharmaceutical industries, where they enable control and measurement work with gases, oil, fuel, alcohols, and acids, and perform quantitative evaluation of liquids.

Water Level Sensor

This equipment is also widely used in metallurgy and mining industries to assess groundwater levels or liquids in wells and reservoirs. Additionally, they are necessary for environmental monitoring, including measuring the volume of tanks with technical and drinking water at plants and settlements, and for monitoring the condition of natural water bodies.

Hydraulic Level Indicator

High-quality modern equipment is used to solve the following tasks:

• Continuous monitoring of liquid level in a container and its pressure, regardless of composition and contamination level;
• Assessment of liquefied gas quantity in industrial tanks;
• Pressure control in various hydraulic and pneumatic systems – pumps and compressors;
• As critical level detectors;
• Control of filling irrigation systems, sprayers;
• Commercial accounting of various liquids;
• Monitoring the filling process of septic tanks;
• As a protective element in systems with well pumps: preventing dry run;
• Inspection of narrow hard-to-reach places in pipelines.

Principle of Operation of Hydrostatic Level Gauge

The submersible well level sensor measures hydrostatic pressure. This method allows determining the height of the liquid column depending on the pressure acting on the vessel’s side walls or bottom. According to Pascal’s law, hydrostatic pressure depends only on the height of the column and the density of the liquid, while the shape and total volume of the tank do not affect this value.

Therefore, a sensor can be fixed stationary on the tank’s side surface (or a submersible model can be used, where the pressure sensor is located directly in the controlled medium at a certain depth). Accordingly, the device helps measure pressure and then convert this value into volume.

The measurement principle is common for all level gauges, regardless of the chosen design – flanged, submersible, or flanged. It is important to note that they can only measure liquids with constant density.

The type of membrane also matters: an open membrane can only be used where there are no large inclusions in the liquid that could cause damage. A protected membrane can be used for heavily contaminated media, but possible inclusions must be larger than the size of the technological hole. Otherwise, the membrane will need frequent cleaning and may be damaged by mechanical impact.

Advantages of Using a Hydrostatic Level Sensor

With a hydrostatic level gauge, it is possible to measure the liquid column at immersion depths up to 100-250 m. There are also models in special designs for deep-water measurements. The key advantages of such devices include:

• Reliable components, including membranes made of stainless steel and a hermetically sealed housing (protection class IP68) – steel or titanium;
• The cable includes an air-permeable but waterproof filter;
• The ability to choose the length (must exceed the maximum liquid level) and cable material considering the density and aggressiveness of the measured media (for water and water-based liquids, for oils, concentrated acids and alkalis, or high-temperature liquids heated up to +125 degrees);
• Availability of additional temperature sensors, lightning protection in certain models, as well as explosion-proof design in some cases;
• The ability to operate in harsh conditions and at great depths;
• Reliability and durability of the measuring device, its easy cleaning (simply remove the housing from the liquid).

Liquid Level Sensor

The Izmerkon company catalog features models designed for water supply systems, hydrogeology needs, as well as for treatment facilities. Industrial level transducers are also available (including those with digital interfaces).

Sensor Model 26 Y Housing diameter 20 mm Output signal 4…20mA; 0…10V Level transducers of the 26Y series have high accuracy indicators while remaining affordable for most consumers.
Sensor Model 25 Y Insertion hydrostatic level meter Output signal 4…20mA; 0…5V; 0…10V The 23 (S)Y/25 Y series has excellent compatibility due to its increased resistance to electromagnetic fields. According to international CE standards, sensors can be used for level fields of 10.
Sensor Model 36 XW Housing diameter 22 mm Output signal 4…20mA; RS485 Sensors of this series feature exceptionally high measurement accuracy, signal interference resistance, and low power consumption. Programming of measurement range, zero adjustment, and built-in output relay are available.
Sensor Model 36 XS Housing diameter 16 mm Output signal 4…20mA; RS485 The 36XS level transducer is a full analog of the previous series sensor but has better dimensions for installation in piezometer tubes.
Sensor Model 36KyX Housing diameter 32 mm Output signal 4…20mA; RS485 Sensors of this type are designed for use in aggressive acidic environments and brines. They possess all the characteristics of the 36XW series sensors.
Sensor Model 46X Housing diameter 38 mm Output signal 4…20mA; RS485 Sensors of the 46x series are equipped with high-precision ceramic sensors. Designed for small measurement ranges (up to 3 meters of water column). Explosion-proof versions are available.
CASTELLO Model Indicator for digital and analog sensors with liquid level recalculation (including under excess pressure) in tanks of complex geometric shapes.