Is a butterfly valve or a ball valve better for vacuum use?

At the connection point with the reactor, the pressure will never exceed five units, and the temperature will never exceed 200 degrees

It is better to use a ball valve; it is safer.

Thank you all for your suggestions. It seems that everyone is recommending that I use a ball valve, but could someone please explain in detail why a ball valve is the best choice? Thank you!

Taking the temperature conditions into account, a cemented carbide sealed ball valve is used.

Butterfly valves are suitable for flow regulation. Since the pressure loss in the pipeline caused by these valves is relatively high, approximately three times that of gate valves, when selecting butterfly valves it is necessary to take into full account the impact of such pressure losses on the pipeline system. Additionally, the strength of the disc in resisting the pressure of the medium in the pipeline when the valve is closed must also be considered. In addition, the limitations on the service conditions imposed on the elastic seat material at high temperatures must also be taken into account. Butterfly valves have a small structural length and overall height, fast opening and closing speeds, as well as excellent fluid control properties; their structural principle makes them most suitable for manufacturing valves with large diameters. When a butterfly valve is used to control flow, it is crucial to select the correct size and type of butterfly valve to ensure it functions properly and effectively. Generally, in throttling, control regulation, and mud media applications, a short structural length and fast opening/closing speed (1/4 turn) are required. For low-pressure shutdown (small pressure difference), butterfly valves are recommended. In applications involving two-position control, narrowed channels, low noise levels, the presence of cavitation and vaporization, minor leakage to the atmosphere, and abrasive media, butterfly valves can be used. In special operating conditions such as those requiring precise throttling, strict sealing, severe wear, or low temperatures (cryogenic conditions), specialized butterfly valves with a three-eccentric or double-eccentric design and metal seal strips for adjustment are necessary. Centerline butterfly valves are suitable for use in pipelines carrying fresh water, sewage, seawater, brine, steam, natural gas, food, pharmaceuticals, oils, as well as various acids, bases, and other fluids, where complete sealing is required, zero leakage during gas testing is essential, a long service life is needed, and the operating temperature ranges from -10°C to 150°C. Soft-sealed eccentric butterfly valves are suitable for two-way opening, closing, and regulation in ventilation and dust removal pipelines, and are widely used in gas pipes and water pipelines in metallurgy, light industry, power, and petrochemical systems. The metal-to-metal wire-sealed double-eccentric butterfly valve is suitable for use in pipelines for urban heating, steam supply, water supply, as well as for gases, oils, acids, and alkalis, serving as a regulating and shutoff device. The metal-to-metal face-sealed triple-eccentric butterfly valve can be used not only as a programmably controlled valve in large-scale pressure swing adsorption (PSA) gas separation systems, but also in various fields such as petroleum, petrochemicals, chemicals, metallurgy, and power generation; it serves as an excellent alternative to gate valves and globe valves. Selection principles for butterfly valves: (1) Since butterfly valves have a higher pressure loss compared to gate valves and ball valves, they are suitable for pipeline systems where strict requirements regarding pressure loss are not necessary. (2) Since butterfly valves can be used for flow regulation, they are suitable for use in pipelines where such regulation is required. (3) Due to the structure of the butterfly valve and the limitations of its sealing materials, it is not suitable for use in high-temperature and high-pressure pipeline systems. The normal operating temperature is below 300°C, and the nominal pressure is below PN40. (4) Due to its relatively short structural length and the possibility of being manufactured in large diameters, butterfly valves are suitable for applications where a short structural length is required, or for large-diameter valves (such as those with a diameter of DN1000 or more). (5) Since a butterfly valve can be opened or closed by rotating only 90°, it is suitable for use in situations where rapid opening and closing are required. Applications for ball valves. Since balls typically use rubber, nylon, and polytetrafluoroethylene as materials for valve seat seals, their operating temperature is limited by the material of those seals. The shut-off function of a ball valve is achieved by the metal ball pressing against the plastic seat under the influence of the medium (in the case of a floating ball valve). Under a certain contact pressure, the valve sealing ring undergoes elastoplastic deformation in certain areas; this deformation can compensate for the manufacturing precision and surface roughness of the ball, thereby ensuring the sealing performance of the ball valve. Furthermore, since the seat seals of ball valves are usually made of plastic, when selecting the structure and performance of ball valves, their fire resistance and flame retardancy must be taken into account. This is especially important in industries such as oil, chemicals, and metallurgy, where ball valves are used in equipment and piping systems handling flammable and explosive substances. Generally, ball valves are recommended for pipeline systems that require two-position control, high sealing performance, resistance to mud and wear, operation with quick actuation (1/4 rotation to open or close), high-pressure shut-off (large pressure difference), low noise, tolerance to cavitation and vaporization phenomena, minor leakage to the atmosphere, low operating torque, and low fluid resistance. Ball valves are also suitable for pipeline systems with lightweight structures, low-pressure shut-off (small pressure difference), and corrosive media. Ball valves can also be used in low-temperature (cryogenic) equipment and piping systems. In the oxygen pipeline systems of the metallurgical industry, ball valves that have undergone strict degreasing are required. When the main pipelines in oil and gas transmission lines are buried underground, full-bore welded ball valves must be used. When regulatory performance is required, a ball valve with a special structure featuring a V-shaped opening should be selected. In the petroleum, petrochemical, chemical, power, and urban construction industries, ball valves with metal-to-metal sealing are used for pipeline systems where the operating temperature is above 200°C. Selection principles for ball valves: (1) For main pipelines used in the transportation of oil and natural gas, where it is necessary to clean the pipelines and these pipelines are to be buried underground, ball valves with a full-connected structure should be chosen ； For those buried in the ground, ball valves with full-bore welded connections or flange connections are preferred; for branch pipes, flange connections and welded connections, as well as full-bore or reduced-bore ball valves, are used. (2) For the pipelines and storage equipment for transporting finished oil, ball valves with flange connections are used. (3) For urban gas and natural gas pipelines, floating ball valves with flange connections and internal thread connections are selected. (4) In the oxygen pipeline system of metallurgical systems, fixed ball valves with flange connections that have undergone strict degreasing treatment are preferred. (5) For the piping systems of low-temperature media, low-temperature ball valves equipped with valve caps are recommended. (6) For the piping systems of the catalytic cracking units in oil refining plants, lift-type ball valves can be used. (7) In the equipment and piping systems of chemical processing systems that are exposed to corrosive media such as acids and sludges, all-stainless-steel ball valves made of austenitic stainless steel, with polytetrafluoroethylene as the valve seat seal, are recommended. (8) Metal-to-metal sealed ball valves can be used in the pipeline systems or devices involving high-temperature media in metallurgical systems, power systems, petrochemical plants, and urban heating systems. (9) When flow regulation is required, a V-shaped orifice regulating ball valve with worm gear drive, pneumatic, or electric operation can be used. When selecting valves, regardless of the type in question, aside from the constraints imposed by their structure, the main factor is to provide the manufacturer with detailed information about the process conditions and the process system ； Regarding butterfly valves, among the many types available, there are also those designed for higher temperatures and pressures, such as triple-eccentric butterfly valves. Generally speaking, butterfly valves have a lower leakage level than ball valves and are suitable for applications with lower pressure differences.

What is the diameter? Not even knowing the caliber, what kind of silly suggestion is that?