The Sludge Finder 2 sludge interface monitor from Pulsar Process Measurement features a self-cleaning Viper transducer that continuously bounces sonar signals off interface layers in primary or secondary settlement tanks and sequencing batch reactor (SBR) systems, providing a profile of sludge levels, including RAS (return activated sludge) and floc particles. The monitor can track two different echoes with one transducer and output two 4-20mA signals. A second transducer can be added for two channel ability. Radio telemetry (1.86 miles maximum range) is available.

The monitor includes a microprocessor and multifunction display that shows blanket level, echo profile, alarm points, tank depth and multiple tank status. A dropdown menu provides quick setup.

“If you have a 10-foot deep settlement tank or clarifier, and 9 feet of it is solid dense sludge, you might have this huge tank but you only have a foot of dirty water that you can put in and cycle, which is not very efficient,” says Jeff Roberts, president, Pulsar Process Measurement. “Our sensor picks up the falling sludge interface and not just the dense interfaces that are collecting on the bottom over long periods of time. We have the ability to set the unit up to read the hard interface and the light floc interface sitting atop the dense sludge.”

An alternative to manual measurements using gap switches or vacuum probes, the automated meter provides constant sludge readings.

“What an operator gets is repeatability,” Roberts says. “There also are no contamination issues where the guys have to glove-up (when using a manual probe).”

The wall-mounted monitor measures 9.25 by 7.24 by 4.72 inches and weighs 3.3 pounds. Made of flame-resistant polycarbonate, it has an operating range of -13 degrees to 131 degrees F.

A wiper blade sweeps the transducer face, helping clear algae or bacterial growth and gas bubbles that can affect performance.

“What happens in clarifiers is as the biological process proceeds, gas is released,” Roberts says. “Tiny gas bubbles filter to top of the surface. The transducer is sitting there and gas bubbles can collect on the face and get to the point where it’s not touching the liquid because it’s in a gas pocket, which will prevent us from reading the sludge interface.”

The step-motor wiper also discourages hair and debris buildup.

The transducer can be positioned up to 650 feet (200 meters) from the control unit and has a measurement range of approximately 0.98 to 33 feet (0.3 to 10 meters).

Wetted parts are chemical resistant (Valox 357, 315 stainless steel and PVC-R2). The monitor has a backlit LCD with bar graph display, full calibration menu and hot key functions. 850/279-4882; www.pulsar-pm.com.