Working principle and application of bellows valve
principle of operation
Sealing principle: bellows valve mainly relies on bellows as sealing element. Bellows are tubular elements with multiple folded corrugations, which are usually made of metal materials, such as stainless steel. It has good flexibility and scalability. When the valve is closed, one end of the bellows is connected with the valve stem, and the other end is fixed on the valve body. When the valve stem drives the valve core to move downwards, the valve core and the valve seat are closely attached, and the fluid channel is cut off. At this time, the bellows is in a compressed state, and its corrugated structure can effectively prevent the medium from leaking from the valve stem. As the bellows is a continuous sealing barrier, compared with the traditional packing seal, it can provide more reliable sealing performance and avoid the leakage problem caused by packing wear and aging.
Opening and closing principle: similar to other valves, the valve stem is driven by external driving devices (such as manual handwheel, electric actuator, pneumatic actuator, etc.). When the driving device acts, the valve stem moves axially. When the valve is opened, the valve stem drives the valve core to lift upwards, so that the valve core is separated from the valve seat, the fluid channel is opened and the medium can pass through the valve. In this process, the bellows will stretch with the rising of the valve stem, but its sealing performance will always be maintained. When the valve is closed, the valve stem drives the valve core to move downward, and the valve core is attached to the valve seat again, and at the same time, the bellows is compressed and returns to the initial sealing state.
application area
Petrochemical industry: In the process of petroleum refining and chemical production, all kinds of flammable, explosive, toxic and corrosive media are often involved. Bellows valves are widely used in the pipeline system of these media because of their excellent sealing performance. For example, on the inlet and outlet pipelines of crude oil distillation unit and chemical reaction kettle in refinery, bellows valves can ensure that the medium will not leak under high temperature, high pressure and complex medium environment, and ensure the safety of production process. For some chemical products with strict environmental requirements, such as fine chemical industry, the zero leakage characteristic of bellows valve can effectively prevent product pollution and ensure product quality.
Pharmaceutical industry: Pharmaceutical process requires extremely high cleanliness of production environment and quality of drugs. Bellows valves play an important role in the water system, liquid medicine delivery pipeline and clean gas pipeline of pharmaceutical factories. In the preparation and delivery system of water for injection, the sealing performance of bellows valve can prevent the invasion of microorganisms and impurities, and ensure the quality of water for injection meets the pharmacopoeia standards. In the filling process of liquid medicine, bellows valve can accurately control the flow of liquid medicine, ensure the accurate dosage of each bottle of medicine, and avoid the pollution of production environment caused by liquid medicine leakage.
Food and beverage industry: in the production process of food and beverage, health and safety are the primary factors to consider. Bellows valve is widely used in the pipeline system of food and beverage production because its sealing structure is not easy to breed bacteria and there is no leakage to pollute the product. For example, in the beverage filling production line, bellows valves are used to control the flow and on-off of various raw materials (such as juice, syrup, carbonated water, etc.) to ensure the accurate formula of products and the hygiene and safety of the production process. In the production of dairy products, bellows valves protect milk from external pollution and maintain its freshness and nutrients in the processes of milk transportation, sterilization and filling.
Power industry: Bellows valves are used in the fields of thermal power, hydropower and nuclear power. In the steam system of thermal power plant, because steam has the characteristics of high temperature and high pressure, bellows valve can withstand this harsh working condition, and at the same time ensure that steam will not leak and improve energy utilization efficiency. In the cooling system of nuclear power plant, the reliable sealing performance of bellows valve is very important for the transportation of radioactive medium, which can prevent the leakage of radioactive materials and ensure the safe operation of nuclear power plant and the safety of surrounding environment.
Aerospace field: Bellows valves are widely used in the fuel system, hydraulic system of aero-engines and propellant delivery system of spacecraft. The aerospace field requires high reliability and lightweight of equipment. The metal bellows structure of bellows valve not only has good sealing performance, but also has light weight, which can meet the special requirements of aerospace equipment. In the fuel system of aircraft, bellows valve controls the flow and on-off of fuel to ensure that the engine can obtain stable fuel supply under various flight conditions. In the propellant delivery system of spacecraft, bellows valve can work reliably in extreme environments such as vacuum and low temperature, accurately control the injection of propellant, and ensure the smooth completion of spacecraft orbit adjustment and attitude control tasks.
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