An employee was working on a lift to clean a silo and resolve a suction issue. The employee opened the top of the silo to clean out the filter using compressed air. The vacuum for the pump at the bottom of the silo was activated; the employee felt suction on the palm of his left hand. As he tried to move his hand away, his left index finger contacted the blower fan at the top of the silo lid. The employee sustained a partial amputation to his left index fingertip.