Upper and lower hollow cylinders communicate with each other. The diameter of the upper cylinder is larger than that of the lower cylinder. The lower cylinder has an opening through which fluid to be dispensed can be introduced. A piston has an upper vertical hollow cylindrical section open at opposite ends with a first extension in peripheral sealing engagement with the inner surface of the upper cylinder and a lower extension in peripheral sealing engagement with the inner surface of the lower cylinder. An aperture is located in the second extension between its ends. A vertical stem is slidable within and extends through the upper section of the piston. The stem has an enlargement spaced below its upper end. A vertical discharge conduit is coaxial with the piston and stem. An actuator is disposed above the upper cylinder, being secured to the upper end of the stem and having a horizontal discharge channel which communicates with the discharge conduit. The actuator slidably receives the upper end of the upper section of the piston in a region defining a gap. The stem is biased by a spring to close the discharge conduit and to position the enlargement above the aperture when the dispenser is in rest position. The spring is disposed outside the cylinders to exert an upwardly directed biasing force against the actuator and against the upper end of the stem. The piston and actuator can be interconnected in such manner that the dispenser can be placed in locked down position without actuation. This interconnection can be used regardless of the placement of the spring outside or inside the cylinders.