An employee was closing a 2-inch ball valve on a test separator to make repairs to the down side of a low-pressure sand knockout. The employee was about 2 to 3 feet from the ball valve as he closed it; when he got the valve three-quarters closed, the bell reducer pipe on the back side of the ball valve separated in two, releasing pressure in the test separator. The employee suffered sand blast burns to the left side of his body, a broken arm, a sprained ankle, a fractured back vertebra, and a head laceration.