Switches Indicators & Gauges

Level Indicators

Level controls are based on a variety of systems, such as floats, probes or ultrasonic. Level indicators show the user what the level controller has determined. In most cases, the final control signal will be used to operate pumps or valves appropriate to the application. It is important that the level control system is correct for the application, and that expert advice is sought from the manufacturer before selection.

Some level gauges are available in three varieties: transmitter, transmitter with display and as a field indicator.

Level transmitters and indicators can measure normal and flammable liquids in applications where ultrasonic or capacitance units would not operate because of dense vapour, foam or inhomogenity of gas layer above the surface. For installation in hazardous areas, an intrinsically safe supply unit or a Zener-barrier between an ordinary supply unit and the device must be used. 

Industrial Switches

A switch is an electrical component designed to break an electrical circuit, interrupting the current or diverting it from one conductor to another.
A familiar example would be manually operated electromechanical devices (such as the one shown at right) with one or more sets of electrical contacts.
Each set of contacts can be either ‘closed’ (meaning the contacts are touching and electricity can flow between them), or ‘open’, meaning the contacts are separated and nonconducting i.e. electricity cannot flow between them.

The term switch has spread during the digital age, to include a variety of digital active devices such as transistors and logic gates.
‘Switch’ can also be applied to telecommunications networks, and signifies a network that is circuit switched, providing dedicated circuits for communication between end nodes, such as the public switched telephone network.
All these usages refer to devices that control a binary state: they are either on or off, closed or open, connected or not connected.

Industrial Gauges

Most gauges merely indicate whether the dimensions of the test object are sufficiently close to those of the standard; i.e., whether they are in the range between set limits, known as the tolerance, for a particular object. Gauges may operate mechanically or electrically.

Most gauges are usually regarded as fixed-type or deviation-type instruments. Fixed-type gauges are used to indicate whether a given dimension is larger or smaller than the standard. They may be of hard steel, soft steel, or glass. Sometimes chrome plating or tungsten-carbide coatings are used to prevent wear.