Ten Sunoco contractors were taken to hospitals for evaluation yesterday after acid vapor escaped at the oil company's South Philadelphia refinery.

Seven went to Methodist Hospital in South Philadelphia; the others were taken to the Hospital of the University of Pennsylvania, police said. None of the injuries were life-threatening, police said.

Thomas Golembeski, spokesman for Sunoco, said the contractors were being evaluated for possible vapor exposure. The release of hydrofluoric acid occurred about 10:30 a.m., he said.

"Sunoco emergency-response personnel responded immediately, and we secured the area," Golembeski said. "The vapor release was stopped. We do not expect any off-site impact."

He said that the release was under investigation and that it was not known how much vapor escaped.

Hydrofluoric acid, which can be fatal if inhaled, is used in making a gasoline blending component, Golembeski said.