Switches Indicators & Gauges

The NivoCONT is a contact style level switch which is based on the conductivity principle. The NivoCONT is primarily design for use in liquids for pump control.

How they work:

The NivoCONT contains probes which are immersed into the tank. These probes work as contacts for an electric circuit. A connection is then established between the probes and the conductive liquid. This connection is converted to an output signal.  The length of the probe should be proportional to the size of the tank and the level that is being detected. When the probe is no longer submerged it triggers a response to indicate that the tank level is too low. Up to four separate probes can be placed within the tank depending on the model to enable for detection at several different levels.

Advantages:

• Contains no moving parts (i.e. it has a high reliability rating and does not break easily).
• Self cleaning (i.e. low maintenance).
• Contains flexible cable extensions of up to 20 meters (ideal for use in larger tanks).

A range of NivoCONT products can be purchase from Samrad (a switch and levels distributor). For more information click here to see what Samrad have to offer you.

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.

Hydrostatic Tank Gauging

Fluid pressure is the pressure at some point within a fluid, hydrostatic pressure being the pressure at any given point of a non-moving (static) fluid. Fluid pressure occurs in open conditions, such as the ocean, and closed conditions, such as a tank. Pressure in open conditions is usually static, as the motion of waves and currents create only negligible changes in pressure. Closed bodies of water are either static (when non-moving) or dynamic (when moving, or compressed by air).

After determining the pressure within the fluid, the pressure’s constant of integration is equal to some reference pressure within the system. The properties (such as pressure) of a fluid can be determined from a control volume analysis of a cube of water. Since the stress of all sides of the cube must be normal and equal in magnitude, the pressure gradient can be found to be linearly increasing in a potential gradient. The pressure within a fluid will increase linearly as the product of the fluid’s density and gravity.

Purge Control

Hydrostatic level transmitters measure hydrostatic pressure using an air purge connection to the tank. An integral specialised airflow regulator ensures a linear response throughout the entire operating range. LiquiSeal™ or Purge Control differential pressure air flow regulators are highly refined versions of the basic bubbler air control. ‘Bubblers’ are usually a length of open pipe that extends downwards into the tank.

Semrad’s Purge Control offers continuous level measurement with pneumatic or electronic output, and is suitable for corrosive or aggressive liquids. The electronic transmitter can be applied to a maximum depth of 49m in water, while the pneumatic transmitter has a maximum depth measurement of 91m. Both have a flow rate of one nominal cubic foot per hour, and a temperature range between -18° and +82° C (though the actual process temperature limits may be significantly higher depending on the material used for the downpipe and purge airline).