Switches Indicators & Gauges

Level Transmitters

A level transmitter is an electronic device that converts level measurements from a sensor to a display for a user. They can measure the level of both liquids or solids within a defined space or container (water tank, oil drum, etc), sending the data via a signal to a receiver. The receiver can be either a computer-controlled device or to a display for a user to read.

The term ‘hydrostatic’ refers to the pressure that fluids exert or transmit. So a hydrostatic sensor will measure the increase in hydrostatic pressure resulting from the increasing height of the liquid. A displaced electrical charge will accumulate, generating an output signal. Applications include measuring levels in groundwater, deep wells, water towers, rivers, sewage treatment plants and so on.

Hydrostatic Level Transmitter

Semrad Pty Ltd, distributor of high quality industrial level sensors, gauges, switches and transmitters, is dedicated to providing cost effective and technically advanced solutions for measuring and controlling liquid and bulksolid levels. Their products are specifically designed to perform accurately and reliably in a range of environments, including caustic, hazardous, non-contact and invasive configurations. Their years of experience have included thousands of installations worldwide in a range of industries from chemical to wastewater, mining, beverage, electronic, material handling, agriculture, textile, pharmaceutical, medical and environmental.

Semrad’s NivoPress NT-100 is a two-wire hydrostatic level transmitter that can be used in applications from liquids and masses in tanks and vessels to chemicals with dense vapour or gas layers above the surface, foaming liquids, and viscous or corrosive materials. It is controlled by a microprocessor to measure the pressure difference between the hydrostatic pressure of the liquid head above the sensor and the actual atmospheric pressure. The changes in pressure are converted into a 4-20 mA output signal. It features a ceramic diaphragm, scalable analogue output, programmable damping, secondary lightning protection, high overload capability, high accuracy (<0.2%), and a process temperature range of -30° to +100°C. The probe material is made of stainless steel, takes a power supply between 12 – 30V DC, and 8 ranges starting at 0.1 bar.

Magnetic Tracking

Magnetostrictive level transmitters operate through a float containing a magnetic disc moving along a guide tube with a specific magnetostrictive wire in it. Magnetostriction is a property of ferromagnetic materials that causes them to change their shape when subjected to a magnetic field. This conversion of magnetic energy into kinetic energy is quantifiable by the magnetostrictive coefficient L, which is the fractional change is length as the magnetisation of the material increases from zero to the saturation value.

The NivoTRACK operates by having a pulse generated by the electronics sent along the magnetostrictive wire, which develops a twist once the pulse reaches the float’s magnetic field. Reflected from the torsion point, the pulse creates an acoustic wave that travels back along the wire. The 4 – 20mA output of the transmitter is proportional to the elapsed time between the excitation and detection.

NivoTRACK

NivoTRACK is a magnetostrictive level transmitter distributed by Semrad Pty Ltd. A highly accurate float level transmitter working on the magnetostrictive principle, it is suitable for custody transfer measurement of valuable liquids such as fuels, solvents, alcohol derivatives, and so on. It can also be applied in level measurement for vessels of production technologies, the most suitable being liquids free of solid particles and with low viscosity both in ordinary and hazardous locations.

This level transmitter comes in both stainless steel for ordinary applications, and plastic coated for a wide range of aggressive materials. It comes with HART communication, a rigid or flexible guide tube, plug in field display module, intrusion length up to 10m, and a 1mm accuracy. The units with flexible tubes make it possible for more accurate measurement for higher tanks, as well as offering a more convenient way for delivery and installation.

NivoTRACK can be housed in either powder paint coated aluminium or plastic (PBT fibre-glass reinforced and flame retardant). The transmitter also is designed as a single or double float, the latter for continuous measuring of liquid interfaces. It can measure levels, interface level, level difference, and medium temperature at one point.

Level Transmitters

Level transmitters are electronic devices that send measurements of the liquid or bulksolid levels via an electromagnetic signal to a receiver. The receiver can be either a computer-controlled device or a user. This measurement information could be in the form of point level measurements (measurements taken at a specific level or at certain intervals) or as a continuous measurement (measurements within a specified range).

Transmitters usually consist of a power supply, an oscillator that emits the signal, a modulator to change the signal from one wave form to another, and an amplifier to increase the strength of the signal. Transmitters are contained within all electronic communication devices, as it is the unit used to send information. Transceivers are devices that contain both a transmitter and a receiver.

Level transmitters come in a range of different technologies for different applications, including hydrostatic, ultrasonic, capacitance, magnetic float, optical, conductivity and more.

NivoCAP

NivoCAP is a capacitance level transmitter distributed by Semrad Pty Ltd, designed to measure the level in vessels filled with conductive or non-conductive liquids, powders and granular materials. It is best suited for the measurement of conductive liquids in regularly shaped conductive containers, though with the use of an auxiliary probe it can also measure levels in irregular or non-conductive vessels. The probe must be continuously in contact with the medium for accurate measurement.

With capacitance level measuring, the probe is one ‘plate’ of the capacitor with the metallic wall of the vessel being the other ‘plate’. The dielectric of the capacitor consists of either the material itself if non-conductive, or by insulation on the probe if measuring a conductive medium. Level changes in the material may be correlated with changes in capacitance, which are then transformed in a 4 to 20mA analog signal by the electronics in the probe head.