The structure of the dome valve:
      The dome valve adopts a special sealing structure, and the sealing chamber does not contact the sealing ring and dome under normal pressure. After pressurization, the valve achieves a sealing effect. The sealing ring is made of elastic rubber material and embedded in the valve body of the dome valve. The sealing gas source can be connected to the sealing chamber through a cylindrical hole of about 5mm. The valve core adopts a spherical dome, and the contact surface between the valve body and the valve core is machined into a spherical surface, with a gap of about 1mm at the fitting point. The valve core is fixed on the shaft pin and connected to the crank, and the opening and closing of the dome valve is achieved through an actuator connected to the crank. When the dome valve needs to be closed, the spherical dome first rotates upwards to a position perpendicular to the center of the material port, and the pressurized sealing gas is filled into the sealing chamber. The sealing ring expands under pressure and is in close contact with the dome to achieve sealing closure; When the dome valve needs to be opened, the pressurized gas in the sealing chamber must be discharged into the atmosphere first. The pressure in the sealing chamber will be reduced to normal pressure, and the sealing ring will naturally shrink. There will be a sealing gap of about 1mm at the fitting point with the dome. The crank will drive the dome to rotate 90 °, and the valve will open.

The usage characteristics of the dome valve:
      When using on site, the spray tank should first be depressurized to normal pressure, and can only be opened when there is no pressure difference between the top and bottom of the dome valve. Otherwise, when the valve operates, the coal powder quickly washes the sealing ring and dome valve core under the pressure difference, which will accelerate valve wear; The filling pressure of the sealing chamber is 1.6MPa, which is greater than the maximum working pressure of the injection tank of 1.04MPa. Otherwise, the sealing ring cannot fully expand after filling, which cannot achieve the sealing effect, resulting in gaps and coal powder leakage between the sealing ring and the dome.
      Dome valves are often used in pipelines and tanks for gas-solid two-phase injection or transportation, to achieve cutting or closing functions. When the sealing chamber of the dome valve is under normal pressure, the dome valve core, valve body, and sealing ring do not come into contact, and the opening and closing action of the dome valve will not cause wear on various components [1]; After the sealing chamber is pressurized, the sealing ring expands to achieve sealing, and the remaining powder on the dome is squeezed into the sealing sphere to prevent wear on the sealing ring and valve body during flow; The sealing ring of the dome valve is embedded and installed on the valve body, which is the only component in contact with the dome valve core. Even if there is wear, it is easy to disassemble and repair [2]; The sealing contact surface and dome may experience slight wear during long-term production, but after the sealing chamber is filled with pressure, the expanded sealing ring will automatically compensate for the amount of wear generated. Therefore, the wear limit of the dome valve is much larger than that of any other type of valve, with better sealing effect and longer service life.
 
Key points for the installation and use of pneumatic dome valves:
1) Before installation, carefully read this manual and verify the valve model, diameter, and technical parameters.
2) It is strictly prohibited to weld the flange after installing the valve to avoid damaging the valve sealing ring. The installation distance of the valve reserved in the pipeline should be suitable, and gaskets should be added on both sides of the flange.
3) The center of the two pipelines should be coaxial with the center of the valve diameter, and the flange surface should be flat. No significant deviation of the flange surface is allowed to ensure the clamping and normal operation of the valve. Tighten the bolts evenly and symmetrically.
4) The valve has been adjusted and dynamically tested before leaving the factory, and the air circuit is well connected.
5) The main vulnerable parts are sealing rings and valve cores.