Level Sensor

Level sensors have been widely used for a number of years within industry to detect the level of liquids and fluids. There is a variety of level sensor technology available including optical, capacitance, ultrasonic and float. Alan Butcher Components supplies the magnetic float variety, also known as float switches. These are point-level sensors which determine whether a liquid is above or below a sensing point.

How do float level sensors work?
A float sensor is a non-contact switching technology which uses a reed switch and magnet to operate. A reed switch is incorporated within the stem of the product and a magnet within an external float.

Float switch activation

The float moves up and down the stem as the liquid level inside a tank or container rises and falls. The magnet activates the reed switch as it passes turning an alarm, indicator, pump or motor on or off depending on the application.

This type of design is relatively simple and well proven. It is also one of the most cost effective and offers long-term reliability.


Liquid level sensors can be horizontally, vertically or side mounted.

Vertical Float Switch - PLS-041-A-6Side Mounting Float Switch - PLS-080A-6VALHorizontal Float Switch pls092a3pph

They can also be positioned at the top or bottom of the tank or fluid container. If mounted stem up, design engineers must note that operating functions are reversed.

Operating Functions
Typically, level sensors are either Form A or Form B.
Form A – SPST NO (Single pole single throw, normally open)

Level sensor Form A
Form B – SPST NC (Single pole single throw, normally closed)

Level sensor Form B

Liquid Level Sensors
Types of Liquid

Float level sensors work well in a variety of media. It is important to verify that the fluids the float switch will operate in are chemically compatible with the level sensor housing material. The following link provides a guide for the chemical compatibility of various housing materials – https://www.pic-gmbh.com/en/tech-center/housing-materials/application-notes/. It is essential that design engineers test the products prior to finalising their application to ensure the level sensor functions as required.

Thick liquids or liquids that adhere to the float or stem are not suitable for float level sensors as they can interrupt the movement of the float up and down the stem.


As mentioned previously, level sensor technology is widely used within a variety of industries including food and beverage, medical, printing, agriculture, automotive and domestic appliances for either leak detection or level measurement.

Here are some examples of typical applications –
Refrigerators – some modern refrigerators include automatic ice makers. They need to have a water tank to make the ice and the level of water inside the tank can be checked with a float switch. If the water levels drops below a designated point a warning can be issued and the machine will stop producing ice.

Condenser Tumble Dryers – A liquid level sensor inside the water container within the machine will monitor the water level. When the liquid reaches a certain level, the sensor will activate a pump to remove the water.

Steamers – If the water level within a steamer drops below a certain level, a warning will be issued and the machine will no longer produce steam. This ensures that the internal workings of the steamer are not damaged through incorrect use.

Industrial machines – tanks in industrial environments or machines contain operating fluids, lubricants and other crucial materials to ensure the machines operate correctly. The level of these materials can be detected using liquid level sensors.

Level Sensors Supplied by Alan Butcher Components

Alan Butcher Components supply level sensors manufactured by PIC GmbH. We stock their PLS range of level sensors and float switches. PIC stands for Proximity Instrumentation Controls Kontaktbauelemente GmbH. They are a medium-sized, international company based in Nuremburg, Germany.

PIC has its own production facilities in Turkey and China. They have been producing high quality, competitive products for over 40 years. This level of expertise combined with flexible manufacturing facilities enables PIC to respond quickly and efficiently to customer enquiries. It also enables them to develop specific customer solutions for non-standard applications.

We have been working with PIC for over 15 years. This strong relationship enables us to respond to customer enquiries effectively and ensures we are able to provide the high level of service we expect to deliver. For more information on PIC and the range of products they manufacture, you can visit their website at www.pic-gmbh.com

PLS Series
Alan Butcher Components stock PIC’s PLS Series of level sensors and float switches. This range includes the PLS-020 which PIC brands as the smallest magnetic level sensor in the world. It is only 29.5x18mm and fitted with 300mm leads.

Liquid level sensors in Polypropylene, Polyamide and Stainless Steel housings are available in either Form A or Form B types.

Benefits of the PLS Series magnetic level sensors

  • Economical – Magnetic liquid level sensors are one of the most economical means of detecting fluid levels.
  • No power supply required – the magnet within the float changes the state of the reed switch so there is no need for power.
  • Suitable for food contact.
  • IP67 rating for most products.
  • The majority of sensors are UL and CSA approved.
  • RoHS and REACH compliant.
  • Customised versions available. Talk to us about the specifics of your application and we will try to find the most suitable product.

When selecting a magnetic liquid level sensor for your application there are various points you need to consider. These include the following:

  • Size and shape of the fluid container
  • Type of liquid and therefore the sensor housing material.
  • Mounting – side, vertical or horizontal. Top or bottom of the tank.
  • Sensor rating
  • Lead length

Our website post provides more detail on this, so click on the link to find out more – https://www.abcomponents.co.uk/float-switch-selection/

We will also be happy to discuss your application with you. Contact us by:

Call – 01258 456360
Email – sales@abcomponents.co.uk
Website contact from – https://www.abcomponents.co.uk/contact/

Furthermore, we have area sales representatives available to visit if you wish to discuss your application in more detail. Please visit the “contact us” page to call them directly and or send them an email to arrange a call back – https://www.abcomponents.co.uk/contact/

Alan Butcher Components is a UK distributor of electronic and electro-mechanical components. Our core product range includes switches, piezo buzzers, miniature speakers, microphones, IEC connectors, signal lamps & indictor lights, Berker socket outlets and switch systems.