COLLEGE STATION — A controversial method for using water to help avoid grain elevator explosions should not be banned by the federal government, a Texas Agricultural Experiment Station researcher says.
Dr. Calvin Parnell, an experiment station researcher and professor in the Texas A&M University agricultural engineering department, testified before Congress in October that using water mist to suppress dust at grain elevators can reduce the possibility of grain dust explosions and is the most economical alternative for some 7,000 small country elevators.
Parnell, who until September was also a member of the Texas Air Control Board, is a specialist in the area of grain elevator explosions and dust suppression. He also sent comments on the process to the Federal Grain Inspection Service in mid-November.
The FGIS is a division of the U.S. Department of Agriculture that is considering whether it will ban the process. It is taking public comment until Dec. 2 on its recommendation of a ban.
The use of water for dust suppression, a process initially studied by USDA researchers in the early 1980s, has drawn opposition and resulted in investigations of grain facilities and distributors by both government and media. Opponents of the method say it can be used to soak grains, increasing grain weight and decreasing quality.
“I believe the safety benefits from prevention of dust explosions is sufficient justification to oppose a ban,” said Parnell. “It can be a cost-efficient method of complying with occupational hazard standards and air pollution regulations.”
Parnell said he would recommend that federal authorities formulate a rule limiting the total application rate to no more than than 0.5 percent water by weight, or less than one cup per 100 pounds of grain.
“This small amount of drinking-quality water should not impact the grain marketing system,” he said. By comparison, he said, an increase of 10 percent relative humidity could increase grain moisture content by 1.2 percent.
He said there are only three methods of reducing the concentration of grain dust entrained in air at grain transfer points to less than the minimum explosive concentration — pneumatic dust control, adding mineral oil and using water.
“Dust suppression with water is least costly,” he said.
He estimated that an elevator would spend less than 20 cents per thousand bushels for dust suppression with water. That compares to $2 per thousand bushels for oil and even more than that for pneumatic dust control, which requires varying levels of maintenance and energy depending on the elevator, he said.
“Using water would allow for significant savings for the 7,000 country elevators facing compliance with Occupational Safety and Health Administration standards and Environmental Protection Agency regulations,” Parnell said.
He said new Federal Clean Air Act amendments will have a major economic impact on small grain elevators and the use of water might allow some of them to comply with air pollution regulations and stay in business.
Parnell said using a limited amount of water for dust suppression in an elevator is not a simple process. Instead, a uniform application requires a well-engineered system to prevent problems with handling materials and grain quality losses.
He said a small amount of high-moisture grain can result in a “hot spot” in a grain bin that damages the quality of significantly larger volumes of grain, resulting in substantial losses for elevator operators.
“To assume they would abuse the application of water if it is not banned is incorrect. Maintaining grain quality during storage periods is essential for country elevators to remain in business,” he said.
“It is my view that elevator operators will strive to use water for safety and pollution-regulation compliance while maintaining grain quality,” he added. “Quite simply, I believe it would be a mistake to ban water for dust suppression in grain elevators.”
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