Structure of pressure gauge

An improved structure of pressure gauge, comprising:

• a bottom case, wherein the peripheral edge of the bottom case protrudes upward to form a ring base and the bottom case has a pipeline for gas to circulate wherein a seal pad is installed on the ring base around the peripheral edge of the bottom case;
• a pressure measurement assembly, which is installed above the seal pad and is shaped with a plurality of concentric circular waves on the surface thereof;
• a rotation assembly, which comprises a sleeve body and a central rod wherein the sleeve body is installed at and connected to the central location of the pressure measurement assembly;
• the inside of the sleeve body is formed with a spiral part of a spiral shape;
• the central rod is plugged into the sleeve body;
• the side skirt of the central rod has a thread part;
• the upper area of the central rod is formed with a coil slot;
• and top end of the central rod protrudes upward and is installed with a pointer rod;
• a rotating piece is used to drive the pointer rod;
• a pointer is installed on the pointer rod;
• a fulcrum piece, which is installed across between the central rod and the pointer rod wherein the fulcrum piece has a plurality of through holes for installation and penetrating through and is formed with a coil retaining base at one end close to the central rod;
• a coil spring, wherein one end of the coil spring is screwed onto the coil slot;
• the other end of the coil spring is installed on the coil retaining base;
• a scale meter, which is installed between the pointer rod and the pointer, and has a through hole that is correspondent to the through hole on the fulcrum piece;
• and
• an outer case, which is installed outside the bottom case and the fulcrum piece and is covered with a transparent cover body thereon.