Butterfly valves: manual and worm drive, how to choose?

The manual pressure level is low; it is used for cutting off flow. The worm gear requires high operating torque, and the shutdown time requirement is not high

Firstly, turbine valves also belong to the manual type; the only difference is in the direction of operation. Turbine butterfly valves are primarily used in pipelines where there is limited space for operation and where the opening speed cannot be too fast.

If manual operation is required, butterfly valves are installed at a relatively low height above the ground, which facilitates manual handling. If worm gear drive is used, the butterfly valves are installed at a higher height. Our company is a manufacturer of butterfly valves and worm gearboxes: Yongcheng Pipe Rack Co., Ltd., Sheyang County, Jiangsu Province. Phone: 0515-82356556. Website: www.syycgj.com

It seems that the valve manual states that for manual butterfly valves with a nominal diameter > DN200, a worm gear drive box is required to facilitate opening and closing.

It must be related to the caliber size

Hello, original poster. Everyone above has already answered your question; I’d like to add a few more points. Please take a look and choose as appropriate – the disc of a worm gear butterfly valve is installed in the diameter direction of the pipeline. Within the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around its axis, with an angle of rotation ranging from 0° to 90°; when it reaches 90°, the valve is in its fully open position. 　　The worm gear butterfly valve has a simple structure, is small in size and light in weight, consisting of only a few components. Moreover, it can be quickly opened and closed by simply rotating 90°, making operation simple; at the same time, this valve boasts excellent fluid control properties. When the flanged butterfly valve is in the fully open position, the thickness of the butterfly disc is the only resistance to the flow of the medium through the valve body; as a result, the pressure drop across this valve is very small, giving it excellent flow control properties. Butterfly valves come in two types of sealing: elastic sealing and metal sealing. Elastic-sealing valves, where the sealing ring can be embedded in the valve body or attached around the butterfly disc. 　　Valves with metal seals generally have a longer lifespan than those with elastic seals, but it is difficult to achieve a complete seal. Metal seals can withstand higher operating temperatures, while elastic seals have the drawback of being limited by temperature. 　　If a butterfly valve is to be used for flow control, the key is to select the correct size and type of valve. The structural principle of butterfly valves makes them particularly suitable for manufacturing large-diameter valves. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemicals, and water treatment, but also in the cooling water systems of thermal power plants. 　　The commonly used butterfly valves are wafer-type butterfly valves and flanged butterfly valves. A wafer-type butterfly valve is connected between two pipe flanges using bolts, while a flanged butterfly valve has flanges on it, with the flanges at both ends of the valve being connected to the pipe flanges via bolts. 　　In the fully open position, the thickness of the butterfly plate is the only resistance to the flow of the medium through the valve body; as a result, the pressure drop across this valve is very small, giving it excellent flow control properties. Butterfly valves come in two types of sealing: elastic sealing and metal sealing. Elastic-sealing valves, where the sealing ring can be embedded in the valve body or attached around the butterfly disc. 　　I. Applications and main performance specifications: 1.1 Scope of application The D341H-1.6C type metal-sealed butterfly valve is suitable for temperatures up to ≤400°C. 　　The D341X-1.6C type soft-sealed valve is suitable for temperatures ranging from 90 to 100°C. 　　They are suitable as opening and closing devices for industrial pipelines such as those for air, water, steam, and oils. 　　1.2 Performance specifications of the valve Model and specifications Pressure test (MPa) Operating temperature (°C) Applicable media Strength Sealing performance Gas sealing D341H-1.6C DN150 and DN300 2.4 1.76 0.6 ≤425 Water, steam, air, and oils D341X-1.6C DN150 ≤100 II. Working principle and structural description 2.1 Structure: Vertical plate-type structure; the valve stem is integral. 2.1.1 The sealing element of the metal hard-sealed valve consists of a composite structure of flexible graphite sheet and stainless steel sheet, which is installed on the valve body; the sealing surface of the butterfly disc is clad with stainless steel. 　　2.1.2 The sealing ring of the soft-seal valve is made of nitrile rubber and is installed on the butterfly disc. The valve body and seat are surfaced with stainless steel. 　　2.2 Working Principle 　　2.2.1 The design of metal-sealed valves relies on the three-eccentric structure principle; by utilizing the inherent cam effect, all friction between the valve seat and the sealing ring during a 90-degree stroke is completely eliminated. 　　2.2.2 The design of the rubber soft-seal butterfly valve features a single-eccentric structure; unlike medium-line soft seals, once the butterfly disc rotates by about 20 degrees, the valve seat separates rapidly from the seal ring, thereby reducing friction. 　　2.3 Valve actuation method The valve is actuated by a worm gear manual mechanism: rotating the handle 90° clockwise closes the valve, while rotating it 90° counterclockwise opens the valve. 　　3. Materials of main components: Model and specifications Valve body/valve disc Valve stem Seal ring Packing D341H-1.6C DN150 and DN300 WCB 1Cr17Ni2 Flexible graphite + stainless steel Flexible graphite D341X-1.6C DN150 1Cr13 Nitrile rubber Manual butterfly valve Manual butterfly valve The butterfly disc of the butterfly valve is installed in the diameter direction of the pipeline. Within the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around its axis, with an angle of rotation ranging from 0° to 90°; when it reaches 90°, the valve is in its fully open position. 　　Butterfly valves have a simple structure, are small in size and light in weight, consisting of only a few components. Moreover, it can be quickly opened and closed by simply rotating 90°, making operation simple; at the same time, this valve boasts excellent fluid control properties. When the butterfly valve is in the fully open position, the thickness of the butterfly disc is the only resistance to the flow of the medium through the valve body; as a result, the pressure drop across this valve is very small, giving it excellent flow control properties. Butterfly valves come in two types of sealing: elastic sealing and metal sealing. Elastic-sealing valves, where the sealing ring can be embedded in the valve body or attached around the butterfly disc. 　　Valves with metal seals generally have a longer lifespan than those with elastic seals, but it is difficult to achieve a complete seal. Metal seals can withstand higher operating temperatures, while elastic seals have the drawback of being limited by temperature. 　　If a butterfly valve is to be used for flow control, the key is to correctly select its size and type. The structural principle of butterfly valves makes them particularly suitable for manufacturing large-diameter valves. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemicals, and water treatment, but also in the cooling water systems of thermal power plants. 　　The commonly used butterfly valves are wafer-type butterfly valves and flanged butterfly valves. A wafer-type butterfly valve is connected between two pipe flanges using bolts, while a flanged butterfly valve has flanges on it, with the flanges at both ends of the valve being connected to the pipe flanges via bolts. 　　Comparison of the performance of ordinary butterfly valves and gate valves Which one, among ordinary butterfly valves and gate valves with the same nominal pressure and nominal diameter, has better sealing properties and is less prone to leakage? 　　Gate valves have better sealing performance than butterfly valves, although there are also manufacturers that produce butterfly valves with excellent sealing properties. 　　Gate valves are large in size and take up a lot of space. 　　Butterfly valves are small in size and take up little space. 　　When making the specific selection, the temperature of the medium, as well as the valve’s sealing and packing, also need to be taken into consideration. 　　The standards specify that disc valves should be used for nominal diameters greater than 50. 　　The elastic metal-sealed butterfly valve is a **high-priority new product; this high-performance manual butterfly valve features a dual-eccentric design as well as a special inclined-cone elliptical sealing structure. It overcomes the drawback of traditional eccentric butterfly valves, in which the sealing surfaces remain in a state of sliding contact and friction during the opening and closing process from 0° to 10°; it ensures that the sealing surfaces separate immediately when the butterfly valve opens and come into contact to form a seal when it closes, thereby extending its service life and achieving optimal sealing performance. 　　I. Applications Used in the sulfuric acid industry for gas pipelines: at the inlets and outlets of the blast fans in front of the furnace, at the inlets and outlets of the backup fans, for series connection and bypass valves in electrostatic precipitators, at the inlets and outlets of the main SO2 blast fans, for regulation in converters, and at the inlets and outlets of preheaters – all to regulate and control the flow rate of gas. 　　Used in the sulfur burning, conversion, and dry absorption sections of sulfur-based acid production systems, it is the preferred brand of valves for such installations. Users consider it a butterfly valve with excellent sealing properties, smooth operation, resistance to corrosion, high-temperature tolerance, as well as ease of operation and flexibility; it is also safe and reliable, which has led to its widespread use. 　　It is also widely used in industries such as chemicals, petrochemicals, smelting, pharmaceuticals, and food processing, where it serves as a regulating and shunting device for pipelines carrying media such as SO2, steam, air, gas, ammonia, CO2, oils, water, brine, alkali solutions, seawater, nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid. 　　II. Structural Features 　　① The unique three-way eccentric design eliminates frictional transmission between the sealing surfaces, thereby extending the valve’s service life. 　　②The elastic seal is generated by torque. 　　③The clever wedge design enables the valve to achieve an automatic sealing effect that becomes tighter as it is closed, with compensatory properties between the sealing surfaces to ensure zero leakage. 　　④Small in size, light in weight, easy to operate, and simple to install. 　　⑤Pneumatic and electric devices can be configured according to user requirements to meet the needs of remote control and programmed operation. 　　⑥Changing the material of the parts allows them to be used with various media, and lining can be applied for corrosion protection (lining with F46, GXPP, PO, etc.). 　　⑦Continuous structure diversity: butt, flange, weld.

D71 refers to the handle-type version, while D371 is the one with a turbine. Generally, handle-type versions are suitable for DN50-DN150 sizes, whereas turbine-type versions are needed for sizes above DN200, as they make it easier to operate the switch.