The basic component of the valve is the body with a square basis and a lateral outlet provided with the thread for securing a 75 cap under a typical pressure hose of Ø 75. Within the valve body, there is located a spindle provided with a trapezoidal thread. On the lower spindle end, there is a mandrel with the valve mushroom. The mushroom is of a special profile and is vulcanised with rubber. Inside the spindle, there is fitted a spring pressing the valve mushroom, via the mandrel, to the seat being sealed; this avoids the back water direction when the valve is open. On the upper end of the spindle, there is secured a knob for manual valve closing and opening.