• Liquid Level Switch For Almost Any Application
  • Tri-Clamp Style Process Connections
  • Temperatures to +350F
  • No Moving Parts Design
  • 3A Sanitary Design
  • Special RA Polish & Electropolishing
  • Explosion Proof Nema 4X Enclosure
  • 316L Stainless Steel Standard
  • Top, Side, or Bottom Connection

The SL series sanitary level switch has been designed to meet the most critical liquid level detection applications in the food, pharmaceutical, biotechnology, and water treatment industries. Tri-clamp quick disconnect caps are standard for 3A applications and special polished/electropolished finishes of 15Ra or better are available to meet the more stringent demands of the biotechnology and pharmaceutical industries.

The thermal dispersion principle of operation features no moving parts exposed to the process. This provides an extremely reliable and repeatable instrument even in extremely viscous or corrosive applications. The SL series instrument operates by measuring the temperature differential between a heated sensor and a reference temperature sensor. An extremely low power heating element is attached to a temperature sensor and a second temperature sensor is isolated from the heater to provide compensation for changing process temperatures.

The thermal conductivity (not electrical conductivity) of the product surrounding the probe results in a temperature differential between the heated and unheated sensor. This temperature difference is greatest in air and gases, lower in liquids, and lowest in moving or agitated liquids. All liquids that form an interface will have a difference in thermal conductivity that can be detected.


Electronics are available with one or two independently adjustable switch points. The dual switch point option allows one sensor to detect two different interfaces or one interface and another process variable such as fluid agitation or foam.

Temperature monitoring is also available with either a switch output at a chosen temperature or with a linear loop powered 4-20 mA output. One 3 amp SPDT (single pole double throw) relay output is standard with options available for different configurations and contact ratings. Remote electronics are also available for applications with high process temperatures or applications that require easy access to the electronics.

  • Able to survive high temperatures of CIP systems and detect CIP processes.
  • Electropolished sensors available with surface finishes of 15 Ra or better.
  • Wet/Dry: Point sensor detects high and or low level of practically any liquid.
  • Liquid to Liquid Interface: Detects any liquid to liquid interface
  • Agitation Monitor: Detects the difference between agitated and non-agitated liquids or slurries.
  • Overflow/Drain line Sensor: Capable of detecting liquid in partially filled lines.
  • Redundant/diversified Level Indicator: Provides primary or secondary high or low level alarms to meet critical applications that require redundant/diversified technologies.
  • Universal Level Switch: Detects liquids in low or high levels applications regardless of fluid dielectric properties.
  • Foam Detector: Differentiates differences between foam and liquids or foam and gases.
  • Emulsion Detector: Emulsions typically can be detected from their base liquids.
  • Solids in Liquids: Detects solids surrounding sensor probe in settling tank applications.