Switches Indicators & Gauges

Hydrostatic Pressure

Hydrostatic pressure is the pressure at any given point in a static fluid. Pressure in open conditions (e.g. the ocean, the atmosphere, a pond) can be approximated as the pressure in static conditions, since the motion of currents or waves create only negligible changes in pressure. It is the same at any given point because otherwise the fluid would move in the direction of the resulting force.

According to the principles of equilibrium, the pressure of a liquid at rest is isotropic, meaning it acts with equal magnitude in all directions. If a point in the fluid is thought of as an infinitesimally small cube, the pressure of every side of this unit of fluid must be equal. This characteristic allows fluid to transmit force through the length of pipes (a closed condition).

Hydrostatic pressure is useful for determining the levels of liquid in a tank, among other things, using devices such as a hydrostatic tank gauge.

Hydrostatic Bubbler

Semrad Pty Ltd offers a range of industrial level gauges, sensors, switches and transmitters. Their WaterLOG® H-3531 FlashLite™ is a NIST traceable pressure sensor. It combines low cost with high accuracy, as it can directly measure dry gas with accuracy better than 0.02% FSO. It comes with built-in temperature compensation, with an operating range between -40° and +60°C.

This non-submersible pressure sensor has an easy to use Simple RS-232 Menu Interface, and a non-conductive and corrosion proof enclosure. Its SDI-12 output provides measurement data in engineering units (e.g. feet or meters), it is easy to use with the H-355 Gas Purge System and is compatible with the RS-232 Data Logger. It also features extended SDI-12 command for setting the stage to the correct water elevation or pressure. It operates on low currents and deviates less than 0.02% from a staight line referenced to end points.

Oil Separators

An oil separator is a large drum designed to separate production fluids into oil, gas and water. These three components have different densities, meaning they stratify when moving slowly. Gas works it way to the top, water falls to the bottom and oil stays in the middle. The oil and water are separated by a baffle set at the height of the oil-water contact. This allows the oil to spill over the side, trapping the water on the other.

Valves on the oil and water outlets are controlled to ensure the interfaces are kept at optimum levels for separation to occur. Oil separators are used for bulk separation as droplets of water will not settle by gravity and will remain in the oil stream. To remove the last of the water the oil is routed to a coalescer. Any solids will drift to the bottom and this sludge is removed with a mechanical scraper or a sludge pump.

Water and oil separators are used throughout industry, with the oil either being further refined to develop petroleum or the water purified and pumped back into a reservoir or the sea.

Alarm Sensors

Oil separator alarm sensors indicate when the sludge deposit or layer of oil or grease needs to be emptied. The alarm is the only way to be sure when it is economically sound and environmentally safe to collect the hazardous waste.

Semrad’s Oilset 1000 and 2000 are interface level detectors for oil, water, sand, sludge and grease. They feature reset and test functions, no moving parts, high accuracy, a large display, no calibration needed, and explosion proof models. The alarm is audible, can operate in temperatures between -30° and +55°C, and the cabling between controller and sensor can reach up to 3m. They are wall mounted sensors whose internal buzzer and external alarm can be muted. The direction of the alarm can also be changed.

Magnetostrictive Tank Gauging

There are different ways of measuring levels in a tank, whether it be hydrostatic, magnetic float, capacitance, ultrasonic or conductance. Tank gauges are used to determine different variables including levels, condensation, density, or temperature.

Magnetostrictive tank gauges use magnetic tracking to determine the fluid pressure in a closed body of liquid. Magnetostrictive materials change their shape when subjected to a magnetic field, converting magnetic energy into kinetic energy. Magnetostriction is the property of ferromagnetic materials, which have a structure that is divided into domains. Each domain is a region of uniform magnetic polarisation. When a magnetic field is applied, the boundaries between the domains shift, rotating them, causing a change in the material’s dimensions.

LabkoMax and LabkoFlex

The LabkoMax and LabkoFlex systems are designed for reliable, accurate and inexpensive fuel storage monitoring, in applications such as service stations, terminals, refineries and other fuel distribution sites.  These systems easily intensify logistics, optimise storage, detect condensated water and control leaks. They measure product level, temperature and eventual condensed water level. They are based on the magnetostrictive measuring principle, so are ideal for applications demanding high accuracy and good repeatability.

The sensor’s wetted parts are of stainless steel and PVDF, suitable for fuels like gasoline, diesel, fuel oil, various additives and industrial chemicals. They can take measurements from tanks up to 15 m high, are very easy to install and have an IP 68 structure. The LabkoMax is best for tanks that are less than 5 m high, while the LabkoFlex is most suitable for tanks between 5 – 15 m high. LabkoMax sensor can be equipped with one or two floats and optionally with 1 – 5 temperature sensors.

The MPS-4 is the interface and barrier unit of both systems, transforming the measurements into digital information. It is compatible with most common pump controllers, cash registers and outdoor payment terminals. It is also possible to observe the level information of containers in real time online with the LabkoNet® service site.