External and Internal Construction of Pressure Gauges

All pressure gauges are made of stainless steel and filled with glycerin. The purpose of glycerin is to lubricate and keep the needle from vibrating. It has a front ring with a lens on it. On the back side of the pressure gauge are the two screws on the protective cover. The internal skeleton is entirely made from brass except for a copper tube, the Bourdon tube. It is nothing more than a bent tube in a circular formation. It is then attached to the square brass part at both ends. This means that it is airtight. The front face has the calibrations and the needle. It usually measures up to 100psi, where psi stands for ‘pounds per square inches.’ Some pressure gauges also tell the pressure in Kilopascal unit. There is a little pin for the zero calibration that stops it going any further than that point.