To eniarge the using range of all kind of the universal pressure gauge,and make it suited for measuring the pressure of the service medium which is high corrosiveand easily crystallized,or the medium which has floating solid.And in order to prevent some service medium from entering the universal pressure gauge or to be easy for clear the place where the precipitation is resistenced,there must have a diaphgram pressure gauge which is made up of a diaphragm and a universal pressure gauge.