3. Classification according to sealing form
(1) Forced sealing butterfly valve. 1) Resilient sealing butterfly valve. The sealing specific pressure is generated by the elasticity of the valve seat or valve plate when the valve plate squeezes the valve seat when the valve is closed. 2) Applied torque sealed butterfly valve. The sealing pressure is generated by the torque applied to the valve shaft.
(2) Pressurized and sealed butterfly valve. The sealing specific pressure is generated by charging the elastic sealing element on the valve seat or valve plate.
(3) Automatic sealing butterfly valve. The sealing pressure is automatically generated by the medium pressure.

System service and maintenance of pneumatic butterfly valve
The starter needs cooling water, and more cooling lines are connected to the external exhaust manifold. The tank has an exhaust line, usually a copper pipe, from the fuel pump in the tank, and then another hose is connected to the fuel hose of the fuel filter. From there, another hose needs fuel for the carbohydrate or fuel radiation system on the diesel engine, and there is a return line to take unnecessary fuel back to the fuel tank!
Compared with the cost of system service and maintenance of pneumatic butterfly valve at least once a year, some hoses have a service life of 2-3 years. After a long time of use, vibration, heat and fatigue, exchange all hoses and use warm new clamps, all through the double clamps of rubber hose body. The hose only needs to meet the minimum SAE specification and survive within the warranty period, which is usually only 1 year. Some hoses have a 2-year, 3-year or 5-year warranty. When you enter the high-end flexible silicone exhaust hose, there is a 10-year warranty period, but it does not mean that you can neglect the hose for 10 years
Almost all yacht inboard engines send their exhaust and cooling water through high temperature hoses and full exhaust pipes in the crossbeam, or through the drive unit and through the propeller hub. For all hoses and pipe joints, if the pneumatic butterfly valve is equipped with tap water at the kitchen head, the cockpit refreshment center or the ice machine on the bridge. All these hoses are the thoroughfare for the flow of liquids and gases that make your rubber hoses work.