Level switch

Level Switches are sensors with an electrical contact output at a specific liquid, powder or bulk level. 

This is a simple limit switch based level switch. When the float moves with the raise in level then the output contact changes & it indicates the level position.

What is level switch?

A level switch is a sensor that detects the presence of liquids, powder, or granulated materials at a specific location.(It is also referred to as level sensor) For example, when a tank is supplied with liquid, it overflow.In order to prevent overflows, a level switch is installed near the top of the tank. When the liquid touches the level switch, it outputs a signal to keep the liquid from overflowing the tank. (To detect that a tank is filled with material is referred to full detection, or upper limit detection.) On the other hand, when the liquid level drops as the liquid is discharged, a level switch is used to prevent completely draining the tank. This is referred to as an empty detection or lower limit detection.

different types of level switches

Capacitive Level switch

Capacitive level switches are sensors with an electrical contact output at a specific liquid, powder, or bulk level. 

Their traditional use is for non-metallic materials such as: 

plastics industry,

chemical industry, 

wood industry, 

ceramic and glass industry, 

and packing industry.

A few models are no maintenance.

Conductivity Level switch

Conductivity level switches are sensors with an electrical contact output at a specific liquid level. 

Applications include ponds, reservoirs, sumps, pharmaceuticals, closed vessels and open tanks.

Diaphragm Level switch

Diaphragm level switches are sensors with an electrical contact output. The dry Level Switch is sensitive and very economical.

 Applications include mining, silos, hoppers, and food & beverage. A wide variety of diaphragms is available to match product bulk density, flowability, abrasiveness and temperature requirements.

Displacer Level switch

Displacer level switches are sensors with an electrical contact output at a specific liquid level. Models are suspended on a coil spring. Displacers are not affected by turbulence or pressure and are excellent for applications with viscous or dirty liquids. Applications include foaming liquids, heavy oil refineries, paints & varnishes, and chemical plants.

Float Level switch

Float level switches are sensors with an electrical contact output at a specific liquid level. 

Applications include level control, valve control, deaerators, condensate tanks, oil level control, drip legs, and boilers. A few models are designed for the automation of pumps, specifically filling and draining of tanks, wells, and reservoirs.

Optical Level switch

Optical level switches are sensors with an electrical contact output at a specific liquid level. Dwyer models are low cost and compact. Optical level switches provide rapid response while employing mo moving parts. 

Applications include air conditioning systems, sumps, pharmaceutical, hydraulic reservoirs, and liquid holding tanks.

Paddle Level switch

Rotating paddle level switches are sensors with an electrical contact output at a specific powder or bulk level.

Applications include mining, silos, hoppers, food & beverage, and grain silos. The models within this category have either top or side mounting.

Tilt Level switch

Tilt level switches are sensors with an electrical contact output. 

Applications include large hoppers, trippers, stackers, conveyors, stackers, and crushers. The probes are designed for use where the bulk material to be sensed is exposed or open. The control units feature an adjustable time delay and a logic selector switch.

Tuning Fork Level switch

Tuning Fork level switches are sensors with an electrical contact output at a specific level. Cost effective models are an ideal choice for level control of powders and fine grained solids. Models are easy to use and applications include mining, chemical processing, and food & beverage.

Rod Level switch

Vibrating Rod level switches are sensors with an electrical contact output at a specific powder or bulk level. The Vibrating Rod Level Switch is economical in level detection of powders and bulk solids. Perfect for silo or hopper applications. The probe design allows for self-cleaning, ensuring no build-up or bridging of material and accurate detection.

Level Switch: Construction

Working

Principle:

All float operated liquid level controls operate on the basic buoyancy principle which states “the buoyancy force action on an object is equal to the mass of liquid displaced by the object.”

As a result, floats ride on the liquid surface partially submerged and move the same distance the liquid level moves. Because of this, they are normally used for narrow level differential applications such as high level alarm or low level alarm.

The float rides on the process liquid surface for precisely tracking liquid surface motion.

Rising liquid level lifts the float- to actuate the electrical switch.

Subsequently, falling liquid level lowers the float to deactuate the electrical switch.

Symbol

Application

Float type level switches are generally able to handle high temperature applications, and sometimes prove useful for close interface detection.

• Water level in bottle filling
• Diesel
• Oil
• Chemical
• Milk
• Lubrication 
• Filtration