These are used for liquid / gas / Steam service under normal conditions. The bourdon tube is 'C' shaped and closed at one end. When this is subjected to fluid pressure from the other end, the deflection is created and transmitted via movement to thte indicating pointer over dial. These are calibrated by comparison against master gauges and the accuracy is +/-1% of span with test certificates traceable to national standard. Connection is threaded 1/4", 3/8", 1/2" BSP/NPT. Range upto 1000 Kg/cm2, -760 mm Hg to 0 (Vacuum).