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Bubbler Systems for Liquid Level Measurement

Bubbler Systems for Liquid Level Measurement

Suitable for measuring the level of more challenging or hazardous liquids, such as viscous fluids, slurries, sludge, sewage and liquids with suspended solids. Bubblers are also used for water and downhole (well) measurement.
These systems have no moving parts, which makes them a reliable and robust solution.

The technology has been tried and true for many years and is an economical solution for a variety of environments.
Bubbler System Process

Bubbler System Process

The bubbler system works by forcing a gas (compressed air) at a near constant flow rate out the bottom of an open tube (bubble/dip tube) submerged in liquid. The back pressure in this tube is measured. With the process liquid’s density known, the level can be calculated using the back pressure and density. A pressure transmitter converts the back pressure to provide a 4-20ma output to a controller, which calculates the liquid’s level.

As the liquid level increases, the head pressure on the bubble tube gets higher. This means more pressure is needed to maintain a constant flow rate to overcome the pressure of the fluid.

If the fluid level goes down, so does the head pressure on the bubble tube and the pressure required to maintain constant flow rate of air or gas.  

To minimize maintenance requirements, we can add a purge line to clear the bubble tube of debris and buildup. This can be a manual operation with the push of a button, or automated with a purge schedule and timer.

Advantages of Bubbler Systems:

Advantages of Bubbler Systems:

  • Reliable and long lasting. The bubble tube is the only part that is in contact with the process fluid
  • The transmitter sensor is not in contact with the fluid creating longer life and accuracy
  • Solids, surface foam, temperature, PH and conductivity have no negative effects on measurements
  • High accuracy
  • Suitable in corrosive applications
  • Maintenance is minimized when integrated with an automated purge line for the bubble tube
Bubbler Applications

Bubbler Applications

  • Open top or vented tanks
  • High pressure in-process vessels
  • Wells (level and feedback for intake pumps)
  • Wastewater systems
  • Viscous fluids, slurries, sewage, liquids with suspended solids and sludge
  • Can be used in place of other technologies such as Radar and float
  • All types of liquids
Bubbler Panels


Outdoor -40° to 60°C (40 to 140 °F)
Measurement Range
Up to 4,000 psig (275,8 bar) Gage, Up to 4,000 psia (275,8 bar) Absolute
Communication Protocol
4-20 mA HART®, 1-5 V Low Power HART®, or Modbus RTU, RS485, and Ethernet IP
Process Wetted Material
316L SST
cETLus, Nema 4X,NSF, NACE®, hazardous location, see full specs for complete list of certifications


  • Standard designs
  • Flexibility for custom requirements
  • Fully insulated and heated for outdoor use
  • Single or multi level measurements
  • Adjustable set points
  • Optional: Stainless steel Nema 4X enclosures
  • Optional: Hi/Low alarms
  • Optional: Alarming back to controller
  • Optional: Indicating lights
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