Abstract: Employee #1, of R. E. Logan Air Conditioning and Refrigeration, Inc., was turning an oil drain valve for the north coil of an anhydrous ammonia cooling system in the main process room of a meat packing plant. Employee #1 said the valve was hard to turn and then it became easier. At that point the bonnet of the valve came off. The right side of Employee #1's face, his arms, the right side of his trunk, his back, and his buttocks were sprayed with ammonia. Employee #1 tried to replace the valve, then descended the ladder and was rinsed with water at the front loading dock. He could not locate eyewash that was near the front loading dock in the plant. Employee #1 suffered second- and third-degree burns and some lung damage. He was not wearing personal protective equipment, and he said that ppe is not normally required when turning a valve in a closed system. Employee #1 was trained in safe work practices and was aware of ammonia hazards. He said that he may have unscrewed the threads of the bonnet. The employer tightened the valve and observed no defects like cracks or corrosion. The employer said that Employee #1 may not have used a wrench to check the rotation of the bonnet, but this could not be verified.