The basic component of the ball valves is the body wherein there is located a ball provided with a through-hole of the diameter dependent of the valve size. The body complete with the ball is enclosed with a cover and a flange. The ball is sealed in the body with special-purpose PTFE rings ensuring the reliable tightness of the same. The valve may be opened and closed manually, with use of the lever. The ball driver output from the body is sealed with a special-purpose brass sleeve and with O-rings. The valve make intended under foaming agent feeders are provided with a grading and a pointer enabling to set the appropriate foaming agent concentration value.