1. IN A VALVE FOR MEASURING AND DELIVERING PREDETERMINED QUANTITIES OF FLUID COMPRISING A HOUSING HAVING AN INLET FOR FLUID, AN ELASTIC BLADDER SURROUNDING SAID INLET AND RECEIVING ALL FLUID FLOWING THROUGH, IT, SAID HOUSING PROVIDING A CHAMBER AROUND THE OUTSIDE OF THE SAID BLADDER, EXPANSION AND CONTRACTION OF SAID BLADDER CHANGING THE VOLUME OF SAID CHAMBER, SAID CHAMBER HAVING AN OUTLET FOR FLUID, AND VALVE MEANS INSIDE SAID BLADDER ACTING TO BLOCK THE FLOW OF FLUID THROUGH THE BLADDER WHEN FLUID ENTERS UNDER PRESSURE THROUGH SAID INLET AND THEREBY CAUSING EXPANSION OF THE BLADDER TO REDUCE THE VOLUME OF SAID CHAMBER.