Soreness, pain, hurt-nonspecified injury

On 1/14/2015 at approximately 11:23a.m. an employee was using a blow down system on a National 340 pump to blow out water in the hard line. Once the 4 inch suction hose was drained, the suction hose was disconnected and a cam lock was placed on the suction hose coming from the pump. The four inch butterfly valve for the suction was left open allowing air to pressure up against the cam lock cap. The employee used this system to build air and blow down the fluid in the tubing line to the tank. The employee was standing in front of the manifold and slightly to the right approximately one foot away. When the employee opened up the manifold, the cam lock cap popped free hitting him in the shin.