Level Measurement

Level measurement of liquid media based on the float principle

WEKA has specialised in recording the level of liquid media in tanks whose content cannot be monitored on a directly visual basis by the operator.

Whether on submarines, on offshore platforms, in chemistry or in research, high pressures and/or high temperatures are increasingly being worked with, as are media that are toxic or high-purity. In all cases, the opening of the containers is undesired or not possible, yet the level must be recorded securely and continuously.
For this purpose, WEKA has made use of the principle of magnetic transmission. In a float that floats on the surface or a separating layer, magnets are integrated whose position can be displayed electrically or visually. The magnets are so strong and stable that several millimetres to centimetres of distance can be bridged. This distance means large wall thicknesses of the float chambers and thus safe use in high pressures of the systems.

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Connection type
Application
Resolution
Fixation
Coating
Density of liquid
EAC approval
Ex approval
Counter plug
Accuracy
Halogen-free
Cable outlet
Contacts
Mounting of converter
max. indication length
Application of media
min. indication length
Nominal pressure PN
Process connection
Pipe diameter
Shipbuilding approval
Shock resistance
Welding approval
Float material
Service flange
Signal output (1)
Temperature Range
Death band
Interface measurement
Ozone / UV resistant
Material

Bypass - Visual Level Indicators (VLI)

Three functions combined in one instrument

Magnetic visual level indicators combine up to three functions in one device: level display, switch and transmitter. The display, which is readable across large distances, does not use any energy and functions inevitably owing to the physical law of fluids in communicating vessels.

WEKA magnetic visual level indicators impress thanks to their compact design and their wide range of applications.

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Wide range of applications

Operating pressures of the vacuum of up to 500 bar and more are possible, as well as calculation pressures for the float standpipe of up to PN630. Fluid densities > 0.3 g/cm3 and a temperature range of 77K to 673K (-196°C to 400°C) allow use in applications for cryogenic liquid gases as well as in water hydraulics and in steam boilers. Closed floats for condensing media up to a max. operating pressure of 320 bar are available.

Flexibility thanks to suitable selection of materials

  • Standard materials: 316/316L 1.4435/1.4404, austenitic stainless steel of the A4 group
  • Further possible austenitic stainless steels: 304/304L 1.4301/1.4306, 1.4571, 321, 1.4541
  • Stainless steels with higher Mo content, such as: 1.4539 (904L; UNS N08904), 254 SMO (UNS 31254)
  • Nickel alloys and special metals such as: Inconel/Incoloy/Hastelloy, titan alloys, zirconium, tantalum. Aluminium alloys
  • Plastics: PVDF, PP, PE, PVC, ECTFE coating (Halar), PTFE-PFA lining, PFA coating.
  • In principle, all possible non-magnetic materials are conceivable!

Energy-free, inevitable functioning

The WEKA magnetic visual level indicator is ideal when starting up systems. The display does not use any energy and functions inevitably owing to the physical law of fluids in communicating vessels. Independent of control – and thus also in the event of a power cut – a visual level indicator is guaranteed on site.

Secure readability

The wide, red-silver colour-contrasted leaf indicator is easily and securely readable, even across large distances. The completely transparent leaf indicator in polycarbonate (PC) also ensures lateral readability. The not always unproblematic and also dangerous fluids are securely enclosed in the tight, pressure-resistant float standpipe and are separated from the indicator.

The secure readability of the level indicator is not impeded by turbidity or the translucence of the fluid to be measured.

Level measurement à la carte

As described, WEKA magnetic visual level indicators offer the ideal solution for nearly all operating conditions. For most applications you will find a suitable device from our standard range. However, special solutions are also repeatedly required for special operating conditions. Many versions are usable in dangerous areas according to ATEX or IECEx. Thus, many of our devices are also usable in potentially explosive environments.

Benefit from our many years of experience! Including the time-tested and patented WEKA magnet system for the float and the gauge bar, we have developed and constructed magnetic visual level indicators according to specific customer requirements for over 50 years. If needed, our standard interfaces to your control system can also be installed on these devices. The WEKA leaf indicator can be designed with a different colour contrast of the leaves. The WEKA magnet system with the gauge bar is also used to display stroke positions of hydraulic or pneumatic pistons and pressure accumulator membranes. For all of this, we offer you solutions on request for your special requirement.

A picture, visual magnetic bypass level indicator economy line for up to 6 bar process pressure
EconomyLine

≤ 6bar
-40 … +100°C
≥ 0.60g/cm3
≤ 600cSt

A picture, visual magnetic bypass level indicator smart line for up to 50 bar process pressure
SmartLine

≤ 50bar
-80 … +250°C
≥ 0.60g/cm3
​≤ 150cSt

A picture, visual magnetic bypass level indicator standard line for up to 50 bar process pressure
StandardLine

≤ 50bar
-100 … +400°C
≥ 0.55g/cm3
​≤ 600cSt

A picture, visual magnetic bypass level indicator high pressure line for up to 200 bar process pressure
HighPressureLine

≤ 200bar
-80 … +400°C
≥ 0.70g/cm3
​≤ 600cSt

A picture, visual magnetic bypass level indicator petro line for up to 150 bar process pressure
PetroLine

≤ 148bar
-80 … +400°C
≥ 0.47g/cm3
​≤ 600cSt

A picture, visual magnetic bypass level indicator low density line for up to 50 bar process pressure
LowDensityLine

≤ 50bar
-196 … +400°C
≥ 0.27g/cm3
​≤ 600cSt

A picture, visual magnetic bypass level indicator plastic line for up to 10 bar process pressure
PlasticLine

≤ 10bar
-20 … +140°C
≥ 0.75g/cm3
​≤ 600cSt

A picture, visual magnetic bypass level indicator special VLI for up to 630 bar process pressure
Special VLI

≤ 630bar
-196 … +400°C
≥ 0.27g/cm3
​≤ 600cSt

Accessories & spare parts

Top of Tank - Visual Level Indicators (ToT VLI)

All advantages top of tank​

Instead of on the side of the tank, top of tank magnetic visual level indicators are installed on top of the tank.

The magnet is not located in the float directly, but in a magnetic carrier found above the top of the tank that is connected to the float by a connecting pipe. The float system moves in a guide pipe and the fill level is displayed above the tank, as in the bypass visual level indicators. Thus, all the advantages of the magnetic visual level indicators are available.

Magnetic visual level indicators combine up to three functions in one device: level display, switch and transmitter. The display, which can be read across large distances, works without energy. The float records the fill level directly and inevitably and displays it without further calculations.

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WEKA magnetic visual level indicators impress thanks to their compact design and their wide range of applications.

The WEKA function principle with a horizontal bar magnet ensures clear, operationally safe control of the gauge bar, the switches and the transducer. This is the case even with the biggest wall thicknesses of the float standpipe. Comparable to a compass needle, the float in the standpipe always aligns itself according to the patented rotating magnetic band integrated into the gauge bar. Large functional flexibility is combined with the advantages of the large field density of the bar magnet! Each gauge leaf has its own permanent magnet integrated. Thus, the gauge leaves are magnetically coupled and position-stabilised. Together with the insulating field of the rotating magnetic band, a clear level display is ensured even under difficult operating conditions (e.g. fast level change, vibrations). Select magnetic materials with the smallest degradation of the field strength ensure the preservation of the functional advantages of the WEKA bar magnet principle up into the highest operating temperatures. The low weight of the WEKA bar magnet principle allows a lightweight design of the floats and thus an extremely compact, material-sparing and contemporary design for the standpipe. Also ensured is the greatest possible radial clearance between the float and the standpipe – an advantage in the case of heavily soiled or high-viscosity fluids.

Like the bypass visual level indicators, top of tank visual level indicators offer a wide application range.

The material selection is also flexible.

  • Standard materials: 316/316L 1.4435/1.4404, austenitic stainless steel of the A4 group
  • Further possible austenitic stainless steels: 304/304L 1.4301/1.4306, 1.4571, 321, 1.4541
  • Stainless steels with higher Mo content, such as: 1.4539 (904L; UNS N08904), 254 SMO (UNS 31254)
  • Nickel alloys and special metals such as: Inconel/Incoloy/Hastelloy, titan alloys, zirconium, tantalum. Aluminium alloys
  • Plastics: PVDF, PP, PE, PVC, ECTFE coating (Halar), PTFE-PFA lining, PFA coating.
  • In principle, all possible non-magnetic materials are conceivable!

Energy-free, inevitable functioning

The WEKA magnetic visual level indicator is ideal when starting up systems. The displays works without energy and inevitably. Independent of control – and thus also in the event of a power cut – a visual level indicator is guaranteed on site.

Secure readability

The wide, red-silver colour-contrasted leaf indicator is easily and securely readable, even across large distances. The completely transparent leaf indicator in polycarbonate (PC) also ensures lateral readability. The not always unproblematic and also dangerous fluids are securely enclosed in the tight, pressure-resistant float standpipe and are separated from the indicator.

The secure readability of the level indicator is not impeded by turbidity or the translucence of the fluid to be measured.

Level measurement à la carte

As described, WEKA magnetic visual level indicators offer the ideal solution for nearly all operating conditions. For most applications you will find a suitable device from our standard range. However, special solutions are also repeatedly required for special operating conditions. Many versions are usable in dangerous areas according to ATEX or IECEx. Thus, many of our devices are also usable in potentially explosive environments.

Benefit from our many years of experience! Including the time-tested and patented WEKA magnet system for the float and the gauge bar, we have developed and constructed magnetic visual level indicators according to specific customer requirements for over 50 years. If needed, our standard interfaces to your control system can also be installed on these devices. The WEKA leaf indicator can be designed with a different colour contrast of the leaves. The WEKA magnet system with the gauge bar is also used to display stroke positions of hydraulic or pneumatic pistons and pressure accumulator membranes. For all of this, we offer you solutions on request for your special requirement.

A picture, visual magnetic level indicator top of tank line - stainless steel for up to 50 bar process pressure
Top of Tank Line - SS


≤ 50bar
-80 … +150°C
≥ 0.55g/cm3
​≤ 600cSt

A picture, visual magnetic level indicator top of tank line - plastic for up to 10 bar process pressure
Top of Tank Line - Plastic

≤ 10bar
-20 … +140°C
≥ 0.87g/cm3
​≤ 600cSt

A picture, visual magnetic level indicator top of tank line - special for up to 630 bar process pressure
Top of Tank Line - Special

≤ 630bar
-80 … +400°C
≥ 0.30g/cm3
​≤ 600cSt

Accessories & spare parts

In-Tank - Tank Level Instruments (TLI)

WEKA TLI, continuous level measurement in the tank, as an ideal complement to WEKA magnetic visual level indicators

The continuous level sensors from WEKA are the ideal complement to the WEKA bypass system wherever an outer installation is not possible. Fully electronic and, apart from the float, without moving parts, they deliver reliable level values for remote indication. The XM types work according to the voltage divider principle and deliver output voltages between zero and the supply voltage along the lines of the float status. Most types are also available as an XT version, where an integrated converter changes the voltage signal into a 4…20mA signal (current sink).

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Function principle

The level sensors are integrated vertically into the tank to be monitored and are connected to an external evaluation unit by means of a cable. Within the hermetically pressure-resistant skid pipe, across its entire length, there is a board equipped with reed contacts and resistances. By means of the magnets integrated into the float, the reed contacts are activated, which, by means of the resistances, trigger a signal change on the lines of the fill level.

The voltage divider principle

The electronic components are set up in such a way that they switch in a controlled 2-3-2 sequence by means of a defined magnetic field. This produces a virtually linear output signal with high repetition accuracy and offers the advantage that, in the event of a single reed failing, the entire device will not fail, but there will be only a mismeasurement of one measurement step.

The float technology

The tried-and-tested, robust float technology allows the true level to be recorded, without the aid of extrapolated values from indirect measurements, such as pressure or echo, and independent of the temperature and air pressure fluctuations. Thus, secure, direct measurement is ensured, including in tanks with curved walls or where continuous, vertical accessibility is not possible.

The float technology makes it possible, as the only measurement principle, to record separating layers of two fluids in practically all tank sizes and shapes. Wherever two non-mixing media with a density difference of more than 0.1 g/ccm are to be measured, WEKA TLIs deliver the exact fill level of the separating layer.

IndustryLine

≤ 20bar
-20 … +150°C
≥ 0.60g/cm3

HeavyDutyLine

≤ 140bar
-20 … +80°C
≥ 0.50g/cm3

Level switches

≤ 50bar
-20 … +80°C
≥ 0.60g/cm3

HeavyDuty cables

≤ 90bar
0 … +85°C
 

Accessories & spare parts