Wednesday, March 14, 2018

Bubbler-Tube Liquid Level System

bubbler tube liquid level measurement system
The Type L100 is a complete and ready to use
bubble-tube liquid level measurement system.
Image courtesy ControlAir, Inc.
Measuring liquid level in an open tank or vessel can be accomplished in a number of ways, all of which require some arrangement of instrumentation to either infer the liquid level from the measurement of a related physical property, or directly deliver the liquid level visually using a scaled gauge arrangement. One indirect method of level measurement is often referred to as the bubbler or bubble-tube method, so named because it employs a purging gas that continually vents from the bottom of a tube extending into a tank of liquid. Through a simple apparatus, the level of a liquid can be inferred by the amount a back pressure exerted upon the gas flowing through the tube.

Probably the greatest advantage of this method of liquid level measurement is that the media does not contact the sensing instrumentation, protecting the instrument from damage by the media, and the media from possible contamination from the sensor. The only portion of the apparatus in contact with the liquid is a tube immersed into the tank. Basically, a purge gas flows through the immersion tube and may bubble out the immersed end of the tube, which is open to allow the contained liquid to exert a hydrostatic pressure on the purge gas. The back pressure on the gas that is exerted by the liquid contained within the tank will vary directly with the depth of the liquid. The back pressure can be correlated to a liquid level. Further calculations, which would include the tank shape, dimensions, and the liquid density can provide an indication of the volume and mass of the liquid.

It is feasible to create your own bubbler system, but the cost in human resources to design, coordinate, procure, and assemble all the components is unnecessary. ControlAir provides a completely designed and pre-assembled unit, compact and ready to run on your application. More information is included in the datasheet below. Share your process measurement challenges of all types with measurement specialists. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.