Tank or Vessel Level Control Monitoring

In level control and detection applications, the liquid level of a tank or vessel will vary at a continuous pace over a period of time. In order to know when failure occurs or when the level goes dangerously high or low, it is critical to have a level control monitoring solution in place to prevent expensive damage, flooding or run dry situations.

A single point optical liquid level switch installed at the points in the tank or vessel deemed to be critical will prevent over spilling or equipment failure using level control. In many cases, this has proved to be an affordable, small investment that adds value to products and services as it minimises the risk of, in some cases, costly consequences.

Typically, the single point level switches are mounted at the high and low level points of the tank or vessel. From low power switching to those capable of handling higher voltage inputs and a larger output drive these switches can sound an alarm, send a signal to a process controller or cut power to pumps and valves.

SST offer a broad range of single-point optical liquid level switches. A vast range of sizes, materials, housing styles and electrical connections are available to meet customer application requirements.

Liquid Level Low
Liquid Level Mid
Liquid Level High

SST’s point level switches are unlike other technologies as they have a long operating life, low sensitivity to ambient light and are solid state – so there are no moving parts to fail. Their ability to function in wide operating temperatures and harsh liquid media result in a highly reliable sensor for use in extreme conditions. The level switches are compact, meaning they can fit into applications where space is limited and they can also very quickly react to small amounts of liquid.



SST’s point level switches are used as level indicators various industries such as industrial, domestic, medical, marine, aviation and transportation. Common level detection and level control applications that SST have had experience with over the years are; High/Low level indication of/in;

  • Hydraulic fluid
  • Water storage tanks
  • Transmission fluid
  • Off-road vehicles and machinery
  • Submarine torpedo tubes and water separators
  • Dialysis machines
  • Testing machinery for electrical protective gloves
  • Water level in neonatal incubator
  • Automated refilling, low/high level processes in;

  • Medical
  • Process control
  • Domestic products
  • Food and beverage applications
  • Fluid levels in off road vehicles, aircrafts and static equipment

  • How does the sensor work?

    The optical liquid level switch uses an infra-red LED and phototransistor accurately positioned at the base of the switches tip. When the tip is in air, the infra-red light from an LED is internally reflected round the tip and back to a phototransistor. When the tip of the switch is immersed in liquid, the infra-red light escapes from the tip causing a change in the amount of light at the phototransistor which makes the output change state.

    Liquid Level Operation