Mercury, a highly reactive and toxic substance, can damage the central nervous system, kidneys, lungs, and brain when one is exposed to high enough doses. Mercury poisoning may trigger symptoms including swelling, peripheral neuropathy, and skin-shedding. Scientists in the Remote Systems Group of the Oak Ridge National Laboratory (ORNL) who have handled elemental mercury transfers are well aware of its hazards.

The team initially conducted mercury transfer as part of the Spallation Neutron Source (SNS) project and later the MERcury Intense Target (MERIT), a high-energy physics collaboration for demonstrating a flowing mercury-jet target in an intense magnetic field. More recently, ORNL researchers investigated the structural integrity of decades-old mercury storage flasks which required transferring mercury into new flasks.

Far-reaching Implications

ORNL is a US Department of Energy (DOE) facility that delivers technical breakthroughs in clean energy and global security. As the largest DOE science and energy laboratory, ORNL's research and development in neutron science, materials science and engineering, and nuclear science and technology have far-reaching applications. ORNL's examination of the properties of materials at a subatomic level, using the SNS, may ultimately lead to improved medicines, metals, plastics, and ceramics.

Yet, mercury transfer can be a risky business. The project's engineers and technicians put on side-shield goggles, nitrile gloves, lab coats, and safety shoes according to ORNL's safety standards. With precautionary respirator training and the use of snorkels and fume hoods to mitigate vapors, scientists are relatively well-protected. However when using centrifugal and/or vacuum pumps to transfer the substance, the pump mechanics became contaminated. The team needed a better solution.

"At the time, we investigated 'blood pumps' which are used in the medical and food industry," explained Philip Spampinato, an ORNL senior engineer. "That search led us to peristaltic pumps, which led us to the Masterflex? pump."

The Right Technology for the Task

The Remote Systems Group has used Masterflex pumps for fluid transfers since 1999. More recently, when it came to transferring 76 pounds of mercury from a standard storage flask into containment vessels, the Masterflex I/P? Precision Brushless Drive with Analog Remote proved to be advantageous on many levels. Along with the Masterflex I/P Easy-Load? pump head and compatible Tygon? long-life tubing, the pump system solved several of the group's dilemmas at one time.

"The quantity of mercury flow can be controlled by varying the pump speed and occlusion," said Spampinato. "The mechanical components of the pump do not become contaminated.

The mercury only comes into contact with the tubing. This decreases the risk of exposure to elemental mercury and its vapors. We only need to be concerned about safely discarding the tubing when it becomes necessary to replace it. Finally, because the tubing is clear, the operator can visually observe the transfer. This provides an added level of confidence that the process is working well." It also automates a process that might have otherwise been handled manually, a prospect that is both ineffective and potentially hazardous.

"The Masterflex pump system is a significant advantage compared to pouring mercury out of a flask that weighs about 80 pounds," said Spampinato. "While the viscosity of mercury is similar to water, its density is 13.6 times that of water and it is a nonwetting liquid. Therefore, controlled pouring is virtually impossible."

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