The valve is applied in the industry of bathroom furniture, the industry of manufacturing urinals or dry urinals that do not drag waste through water. The valve provides a water seal that does not require dragging water; it is the urine itself that achieves the seal without the odor developed by the urine of the water seal returning to the users' space. A seal is provided by spheres avoiding the use of consumables, such as sealing oil, scent pads, among others. An outlet valve is provided, in a waterless urinal, towards the drainage, preventing the return of foul odors, including a hydraulic trap formed by a tank where a certain volume of urine is formed, a funnel that discharges the new urine into the bottom of the tank, and an upper valve where the seal is carried out by one or two spheres in their respective seats.