Radar Provides New Depth Measurement Solution

Second generation Depth Ray from Eldredge Equipment takes variables out of level monitoring.
Radar Provides New Depth Measurement Solution
John Eldredge Jr., right, manager of Eldredge Equipment Services Depth Ray division, discusses the unit with an Expo attendee during the 2014 event.

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Several years ago, John Eldredge Sr., the owner of Eldredge Equipment Services, and his son, John Jr., were growing increasingly frustrated with the technology on the market for determining depth in tanks of their fleet of vacuum trucks. So the pair took matters into their own hands, developing the Depth Ray liquid level monitoring and control system. The duo used the 2014 Pumper & Cleaner Environmental Expo International, the company’s first as a stand-alone exhibitor, to introduce the second generation model of the unit.

“We just needed a solution that would work for us,” says John Jr. “We’d used rods and float balls in the past, but they weren’t accurate in thick liquid and can get stuck up with rags, strings, grease and other debris. The Depth Ray eliminates that problem.”

The unit can operate in vacuum or pressure, or in heavy material in mobile or stationary tanks. It contains no rods or floats and is constructed of chemical-resistant components. It features a wireless remote and optional controls for valves and alarms, and is unaffected by most foam or density. It can be installed in any tank or container and exceeds DOT requirements.

“The unit actually sends a radar pulse from its antenna to the surface of the material being measured, then back to the antenna,” says John Jr. “Taking the time interval for that radar pulse to return equates to the level reading. The unit is accurate to 1/10th of an inch.”

The Depth Ray radar system was extensively tested by Eldredge Equipment, at first being put to use in lined tankers in hydrofluoric acid service. The system allowed the company to eliminate the primary shut-off system, as its setpoint control relays are used to control a primary shut-off valve, preventing overfill.

“The unit underwent testing in our fleet in the hydrofluoric acid, waste oil, waste solvent, gasoline and caustic service trucks for more than two years,” says John Jr. “We wanted to hold back on offering them to the tank truck industry until we had completed our testing.” The system was also tested for fleets that haul yellow grease with vacuum tanks ranging in size from 300 to 4,000 gallons. Since yellow grease is a commodity purchased from the generator, it is critical the operator accurately knows the amount of gallons of grease being loaded.

“When you drive a vacuum truck, that load in the vacuum tank is your livelihood,” says John Jr. “It’s important to know exactly how much material is in your tank.”

Accuracy depends on the calibration chart supplied by the customer or the tank manufacturer. The tests Eldredge has done indicate it can read within 7 gallons in a 3,600-gallon used-oil collection tank truck. It is not affected by foam or product density. Because it is noncontacting, it is also ideal for use with volatile liquids.

“There was a need in the industry to be able to measure hazardous waste that could eat away other ‘contact-type’ systems,” says John Jr.

The latest-generation system offers an enclosed eight-figure digital display, LED alarm and alert lamps embedded in the circuit board, push buttons mounted on the enclosure that ensure weathertightness, an LED auxiliary input signal “on” lamp, auxiliary system option for 12-volt input signals from devices like onboard scales, and a feedback confirmation LED lamp indicating a valve or auxiliary system has physically operated.

Options include four compartment level displays, or the option to interconnect up to four additional tanks to a single display enclosure; the ability to set and override valve optional equipment setpoint controls like valve closure and PTO controls; and a timer feature to reset the override. The company’s Remote Monitoring and Control Unit provides wireless remote tank level and system control up to 500 feet from the mounted display enclosure.

The response at the Expo was overwhelming at times, according to John Jr. “We talked to a lot of truck manufacturers that were very excited about the potential of this technology,” he says. “We gathered some ideas that we’ll take back and try to work with for the future. This is certainly a technology that we’d like to develop for different uses, including permanent solar-powered units for septic and holding tank measurement. We’re excited to see where it ultimately goes.” 800/220-2052; www.depthray.com.


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