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August 2007

Solving real-world problems earns Chang-Dong Feng ISA’s Beckman Award

By Jim Strothman

“It helps control corrosion in metal pipes, which contain water flowing at high temperatures and under high pressure. Because of the temperature and pressure, power industries need to be sure the water doesn’t ‘attack’ the pipes and corrode them.” —Feng

For decades, free chlorine—the active form of chlorine that kills bacteria and algae—has been widely used as a disinfectant by the drinking water industry, and for cleaning pools, bathtubs, and spas. However, an estimated 30% of the U.S. drinking water industry, in recent years, has begun using another form of chlorine, monochloramine (NH2Cl) instead of free chlorine.

That is because tests have shown free chlorine can trigger carcinogen byproducts, when combined with certain substances in water being treated. Also, the disinfecting lifetime of free chlorine is shorter than that of monochloramine.

However, drinking water suppliers converting to monochloramine had a problem. They lacked a reliable and wide-range monochloramine sensor. So in 2003, a small team of sensor experts led by Dr. Chang-Dong “CD” Feng at Rosemount Analytical Inc. successfully developed a patented design for monochloramine sensing. That work led to Rosemount’s Model 499ACl-03 product now widely used by U.S. drinking water suppliers. The sensor provides stability and linearity with a range of 0-20 parts per million (ppm).

The monochloramine sensor’s invention is among an impressive list of achievements that resulted in Feng, senior manager of sensor technology for Rosemount, an Emerson Process Management company, being awarded the 2007 ISA Arnold O. Beckman Founder Award. Given in honor of Dr. Arnold O. Beckman, founder of Beckman Instruments (now known as Beckman Coulter, Inc., Fullerton, Calif.), the award recognizes “an outstanding development in instrumentation that has had a significant contribution to the advancement of a technology.”  Feng’s citation credits him “for the research and development of advanced electrochemical sensing and instrumentation.” 

Beckman, who served as ISA President in 1952, was an internationally recognized scientist, educator, executive, humanitarian, and civic leader. He died in 2004 at the age of 104. “Dr. Feng is being recognized for his contributions in the development of advanced electrochemical sensing and instrumentation for analysis applications,” said Gerald Wilbanks, P.E., chair of ISA’s Beckman award committee. “One area of development was a self depleting amperometric sensor for low level dissolved oxygen measurement with increased accuracy and detection capabilities. Several other devices are covered by patents and include an electrochemical gas sensor, a pH sensor with internal solution ground, and a chloramine amperometric sensor,” he said.

“Dr. Feng has authored numerous papers on these topics and made presentations to various conferences concerning analytical advances and innovative measurement technology. His abilities to cross boundaries among scientific disciplines has brought electrical engineers, mechanical engineers, and chemists together for leading-edge development of practical solutions to difficult measurements,” Wilbanks said.

“I’m very excited I won,” said Feng, who holds a Ph.D. from Nagasaki University, Japan, and completed post doctorate work at Illinois Institute of Technology.

Developed oxygen sensors

In 1998, while then working for Teledyne Instruments, Feng developed an ultrafast oxygen sensor, now Teledyne’s UFO-130 product, used in hospitals and sports physiology, as well as for monitoring oxygen levels in food packaging.

A potential life-saver, the sensor is the first microfuel cell-based oxygen gas sensor that reaches a 90% response time in 100 milliseconds at ambient temperature. 

“Doctors, and especially anesthesiologists, wanted to measure the oxygen profile in a patient’s breath during surgery,” Feng said. “Under anesthesia, patients cannot tell you if they feel pain. By measuring oxygen and carbon dioxide level in a patient’s breath, a surgeon may be able to estimate the status of the anesthesia, so they don’t overdose the patient.” Sports physiology—measuring the oxygen level in athletes—is currently another large market for the device, he said.

Electrical power-generating companies are major users of a Rosemount Analytical product developed by Feng’s team, the 499ATrDO, a low-level, part per billion (ppb) trace oxygen sensor. 

“It helps control corrosion in metal pipes, which contain water flowing at high temperatures and under high pressure. Because of the temperature and pressure, power industries need to be sure the water doesn’t ‘attack’ the pipes and corrode them. They need a have a sensor to monitor that.

“In the past, that technology was developed in Europe, but the device was relatively complicated and costly,” having a guard-ring electrode, Feng explained. “The concept I developed made it simple and lowered the cost” by eliminating the guard-ring.  Feng estimated it can reduce costs by half and “improves performance even better than that because you have fewer components to worry about for maintenance, and less failure.”

“The 499ATrDO sensor development project becomes the first R&D project that is led by  mathematical modeling rather than by ‘test-and-see,’ ” said Mark Bleak, vice president of R&D/Engineering for Rosemount Analytical’s Liquid Division, in a letter endorsing Feng’s nomination for the Beckman award. “Our sales in the high purity water ppb DO (dissolved oxygen) application are now 10 times more than that prior to the 499ATrDO release.”

Free chlorine sensor

After developing the monochloramine sensor being widely installed by the U.S. water industry, Feng and a Rosemount colleague in 2006 designed the Model 498 free chlorine sensor. Widely used in South America, and elsewhere, Feng said the Model 498 is unique, because unlike other free chlorine sensors, which are pH dependent, the Model 498 is pH independent, eliminating the need and cost for a pH sensor. Other traditional methods for using free chlorine in water treatment require reagents to measure water color, which can be costly and environmentally suspect, Feng said.

Holder of seven granted patents, and numerous others still in the approval process, Feng also demonstrated expertise in sensor instrumentation by eliminating a problem with Rosemount’s Model 1055 analytical instrument, a mid-tier heavily sold instrument with two-measurement capability.

After the product was released, some users found a pH/connectivity sensor combination because the pH sensor did not have its own solution ground. Feng figured out the problem was due to a ground loop, which involved the junction of the pH reference electrode. By jumping the solution ground and the reference electrode on the instrument with a capacitor, the problem was solved. His solution enabled Rosemount to avoid major re-engineering of the instrument and also led to one of his U.S. patents.

“It does not take long to realize the strength in (Feng’s) academic training, and his R&D style of approaching real world challenges with scientific understanding,” Bleak said. “All of his inventions are built on the science of the problem combined with the principle of the solution.”