This image shows a constant level tank with an elevated bridge with vent. The bridge is enclosed and the cover must be at least two times the diameter of the largest supply pipeline. The cover of the constant level tank must be light enough that if the milk reaches the flood level, the cover will be lifted. The air break above the flood level must be at least two times the diameter of the largest return pipeline. The size of the vent pipe must be the size of the largest return pipeline or larger. Raw milk well at the bottom of the tank must be at a level below the bottom of the tank.