Principle and characteristics of three-eccentric butterfly valves
Thread Content
With the rapid development of modern industrial technology, butterfly valves are widely used in pipeline control systems, especially in those for large-diameter pipelines where other types of control valves fail to meet the requirements. To address the structural shortcomings of double-eccentric butterfly valves, improve their performance, and meet higher requirements of operating conditions, a triple-eccentric butterfly valve was developed. Its features include the use of an eccentric parabolic sealing surface in place of a spherical sealing surface, as well as a floating metal valve seat instead of a fixed metal valve seat. The new type of triple-eccentric butterfly valve consists of a valve body, valve seat, valve stem, butterfly plate, and sealing ring; its feature is that the right-angled pressure angle of the metal sealing ring is greater than the friction angle of the material. This utility model ensures that the deformation of each point on the periphery of the sealing ring is sufficient after being subjected to force, by requiring that the pressure angle around the sealing ring be greater than the friction angle of the material. As a result, the sealing ring does not experience self-locking due to its deformation, which **significantly improves the sealing performance of the valve. This new model also boasts advantages such as a simple and rational structure, a long service life, and a wide range of applications. Structural principle of the triple-eccentric butterfly valve: Single eccentricity: The rotation center of the valve stem is offset from the center line of the valve seat, ensuring sealing between the valve seat and the valve disc. Second eccentricity: The rotation center of the valve stem is offset from the center line of the valve seat; when the valve is opened, the sealing surface of the butterfly disc quickly separates from the sealing surface of the valve seat. Third eccentricity: The center of the sealing surface on the Vertebral body is offset from the valve’s center line, which eliminates any contact and friction between the butterfly disc’s sealing surface and the valve seat’s sealing surface when the valve is opened or closed. Main features of the triple-eccentric butterfly valve: 1. It can withstand pressure in both flow directions, allowing for installation without any restrictions on flow direction. 2. Full-metal sealing design: the valve seat and sealing rings are fabricated using Stellite alloy surfacing technology, which solves the problem of poor sealing performance in butterfly valves under severe operating conditions such as high temperature and pressure, as well as low temperatures ； It can withstand pressures up to 2500 pounds, temperatures ranging from -196 °C to 850 °C, with zero leakage in terms of sealing, and a control ratio of over 100:1. 3. The valve seat and valve body are designed as separate components, as are the valve disc and seal ring; this allows for interchangeable use of different components in the product. The entire valve does not have to be discarded due to seal wear; simply replacing the valve seat and seal ring allows it to function properly, thereby reducing operating costs. Advantages of three-eccentric butterfly valves: 1. Good sealing performance, which enhances the reliability of the system ； 2. Low frictional resistance, making operation effortless and flexible ； 3. Long service life, allowing for repeated switching on and off ； 4. It has strong pressure resistance and high-temperature tolerance, offering a wide range of applications.
shjovalve.com Pneumatic hard-sealed butterfly valve | D643H Pneumatic triple-eccentric metal-sealed butterfly valve – Jingou Control Valves. Delivery time: 27–34 minutes. D643H Pneumatic hard-sealed butterfly valve. Product overview: The structure of the D643H/D673H pneumatic hard-sealed butterfly valve consists of an imported pneumatic piston actuator and a triple-eccentric hard-sealed butterfly valve; it is commonly referred to as a pneumatic triple-eccentric metal-sealed butterfly valve. The valve seat features a multi-layer structure compatible with hard sealing, featuring exquisite machining and advanced manufacturing techniques. The pneumatic hard-sealed butterfly valve is used in conjunction with an electrical valve actuator; it can be controlled by an input signal of 4–20 mADC along with a gas supply of 0.4–0.7 MPa, allowing for the regulation of parameters such as pressure, flow rate, temperature, and liquid level. The pneumatic hard-sealed butterfly valve, equipped with travel limit switches, solenoid valves, pressure relief valves, and a gas supply of 0.4–0.7 MPa, enables switching operations; it also outputs two pairs of passive contact signals to indicate the open or closed state of the valve. Pneumatic hard-sealed butterfly valves are composed of main components such as the valve body, butterfly plate, multi-layer valve seat, valve stem, and actuation mechanism. Thanks to their simple structure, small size, and light weight, pneumatic hard-sealed butterfly valves and pneumatic triple-eccentric metal-sealed butterfly valves are widely used in pipelines handling corrosive media in industries such as metallurgy, power generation, petroleum, chemicals, as well as in systems for air, gas, flammable gases, and water supply and drainage. Product features of pneumatic hard-sealed butterfly valves: (1) The pneumatic hard-sealed butterfly valve features a triple-eccentric sealing structure, which results in almost no wear between the valve seat and the butterfly plate, offering an increasingly tight sealing effect over time. (2) The sealing ring is made of stainless steel, offering the advantages of both metallic hard sealing and elastic sealing. It provides excellent sealing performance in both low- and high-temperature conditions, and features corrosion resistance as well as a long service life. (3) The sealing surface of the butterfly valve is clad with cobalt-based cemented carbide, ensuring wear resistance and a long service life. (4) Larger-sized butterfly valves feature a lattice structure, which provides high strength, a large flow area, and low flow resistance. (5) Pneumatic hard-sealed butterfly valves have a two-way sealing function; their installation is not restricted by the flow direction of the medium nor by spatial constraints, allowing them to be installed in any direction. (6) The pneumatic device can be installed in multiple positions (rotated 90° or 180°), facilitating user operation. Pneumatic hard-sealed butterfly valve – Technical parameters
Nominal diameter DN (mm): DN50–1000 mm
Nominal pressure (MPa): PN1.0, 1.6, 2.5 MPa
Valve body type: Straight-through cast valve body
Connection types: Flanged, wafer-type
Valve disc type: Butterfly disc
Sealing filler: Flexible graphite, polytetrafluoroethylene
Flow characteristics: Approximately equal percentage, linear
Operating range: 0–90°
Leakage rate Q: Meets ANSI B16.104 Class IV standards
Applicable temperature: Hard seal version – up to 450°C
Basic error: With positioner – less than ±2% of the full stroke
Hysteresis: With positioner – less than 2% of the full stroke
Adjustability ratio: 50:1
Actuators available: GT, AT, AR, AW series of single- and double-acting pneumatic actuators
Control methods: On/off two-position control, 4–20 mA analog control
Pneumatic hard-sealed butterfly valve – Actuator parameters
Actuator models: GT, AT, AR, AW series of single- and double-acting pneumatic actuators
Supply air pressure: 0.4–0.7 MPa
Air supply interface: G1/4”, G1/8”, G3/8”, G1/2”
Ambient temperature: –30–+70°C
Operation mode: Single-acting actuator: Air-shut type (B) – valve opens when air supply is lost (FO) ； Air-open (K) -- Valve position closes when air is lost (FC); Double-acting actuator: Air-close (B) -- Valve position remains unchanged when air is lost (FL) ； Air-operated type (K) – The valve position is maintained in the FL position when air supply is lost. Accessories such as positioners, solenoid valves, air filters and pressure regulators, hold-down valves, limit switches, valve position transmitters, and handwheel mechanisms can be used. It features a new series of pneumatic actuators, available in double-acting and single-acting (spring-return) types, with gear and rack drive for safety and reliability ； Large-diameter valves use series AW pneumatic actuators with fork-type drive; they feature a rational design, high output torque, and are available in double-acting and single-acting versions. 1. Gear-type dual pistons, offering high output torque and a compact size. 2. The cylinders are made of aluminum alloy material, which is lightweight and has an attractive appearance. 3. Manual operating mechanisms can be installed at the top and bottom. 4. The rack-type connection allows adjustment of the opening angle and rated flow rate. 5. The actuator can be equipped with a telecommunication signal feedback indicator and various accessories to enable automated operation. 6. The IS05211 standard facilitates the installation and replacement of products. 7. The adjustment screws at both ends allow the standard product to have an adjustable range of ±4° at 0° and 90°. Ensure the synchronization accuracy with the valve. Pneumatic hard-sealed butterfly valve
Parts and materials
Part name | Material
Valve body | Cast iron, stainless steel, chrome-molybdenum steel, alloy steel
Butterfly plate | Cast steel, alloy steel, stainless steel, chrome-molybdenum steel
Sealing ring | Multi-layer combination of stainless steel and high-temperature resistant asbestos sheet
Valve stem | 2Cr13, 1Cr13 stainless steel, chrome-molybdenum steel
Packaging material | O-ring, flexible graphite
Performance specifications of pneumatic hard-sealed butterfly valve
Nominal diameter DN (mm): DN50～1200
Nominal pressure PN (MPa): 0.6, 1.0, 1.6, 2.5
Test pressures
Strength test: 0.9, 1.5, 2.4, 3.75
Sealing test: 0.66, 1.1, 1.76, 2.75
Low-pressure airtightness test: 0.5～0.7
Applicable media: Air, water, sewage, steam, gas, oils, etc.
Applicable temperatures: Carbon steel: -29℃～600℃; Stainless steel: -40℃～600℃
Design standards for pneumatic hard-sealed butterfly valve
Design standard: GB/T12238-1989
Flange connection dimensions: GB/T9113.1-2000 ； GB/T9115.1-2000 ； JB78 Structural length GB/T12221-1989 Pressure test GB/T13927-2000 ； JB/T9092-1999 Pneumatic hard-sealed butterfly valves – Eccentric principle: (1) Deviation from the center of the pipeline; (2) Deviation from the center of the sealing surface; (3) Inclined cone shape. When the valve is opened, the butterfly disc comes into contact with the valve seat for a brief moment at the time of closure; by utilizing eccentricity 1 and eccentricity 2, the butterfly disc can quickly disengage from the valve seat, thereby reducing wear on the sealing surfaces. This results in low friction torque and smooth operation of the valve. The eccentric conical surface 3 allows the butterfly disc to pass through the inner hole of the valve seat when the valve is opened or closed, thereby achieving a contact seal. Furthermore, the rotational radius of the conical butterfly valve disc is greater than that at the contact point of the sealing pair; as a result, the disc closes more tightly as the valve is closed, enabling self-locking and preventing the disc from moving beyond its intended position. Pneumatic triple-eccentric hard-sealed butterfly valve (eccentric principle) Pneumatic triple-eccentric hard-sealed butterfly valve (sealing principle) Pneumatic triple-eccentric hard-sealed butterfly valve (eccentric principle) Pneumatic triple-eccentric hard-sealed butterfly valve (sealing principle) Pneumatic hard-sealed butterfly valve Connection dimension diagram D643H Pneumatic hard-sealed butterfly valve (flanged type) D673H Pneumatic hard-sealed butterfly valve (wafer type) D643H Pneumatic hard-sealed butterfly valve (flanged type) D673H Pneumatic hard-sealed butterfly valve (wafer type) Pneumatic hard-sealed butterfly valve Connection dimensions Nominal diameter (DN) Main dimensions Flange dimensions L (overall length) H H1 A 1.0MPa 1.6MPa 2.5MPa Flange Wafer D D1 n-Фd D D1 n-Фd D D1 n-Фd 50 108 43 112 625 245 165 125 4-18 165 125 4-18 165 125 4-18 65 112 46 115 625 245 185 145 4-18 185 145 4-18 185 145 8-18 80 114 46 120 645 245 200 160 4-18 200 160 8-18 200 160 8-18 100 127 52 138 675 355 220 180 8-18 220 180 8-18 235 190 8-22 125 140 56 164 715 355 250 210 8-18 250 210 8-18 270 220 8-26 150 140 56 175 800 355 285 240 8-22 285 240 8-22 300 250 8-26 200 152 60 200 850 250 340 295 8-22 340 295 12-22 360 310 12-26 250 165 68 243 925 250 395 350 12-22 405 355 12-26 425 370 12-30 300 178 78 250 1035 450 445 400 12-22 460 410 12-26 485 430 16-30 350 190 78 280 1070 450 505 460 16-22 520 470 12-26 555 490 16-33 400 216 102 305 1190 450 565 515 16-26 580 525 16-26 620 550 16-36 450 222 114 350 1250 650 615 565 20-26 640 585 16-30 670 600 20-36 500 229 127 380 1290 650 670 620 20-26 715 650 20-30 730 660 20-36 600 267 154 445 1455 850 780 725 20-30 840 770 20-33 845 770 20-39 700 292 165 480 1585 850 895 840 24-30 910 840 24-36 960 875 24-42 800 318 190 530 1700 1250 1015 950 24-33 1025 950 24-39 1085 990 24-48 900 330 203 580 1965 1250 1115 1050 28-33 1125 1050 28-39 1185 1090 28-48 1000 410 216 650 2015 1250 1230 1160 28-36 1255 1170 28-42 1320 1210 28-56 1200 470 254 760 2250 1250 1455 1380 32-39 1485 1390 32-48 1530 1420 32-56 Pneumatic hard-sealed butterfly valve Product selection (1) Valve body parameters: series parameters such as nominal diameter, operating pressure, process medium, application environment, and valve body material. (2) Actuator parameters: actuator type, control method, control signal (4-20mA, 1-5V), and operation mode (air-open, air-close). Please provide as many details as possible for these technical parameters, so that our company’s production team and technical staff can select the most suitable option for you. If you have any questions, you can call us; we will do our best to provide you with excellent service! Related names: Pneumatic hard-sealed butterfly valve, D643H pneumatic triple-eccentric metal-sealed butterfly valve
Nominal diameter DN (mm): DN50–1000 mm
Nominal pressure (MPa): PN1.0, 1.6, 2.5 MPa
Valve body type: Straight-through cast valve body
Connection types: Flanged, wafer-type
Valve disc type: Butterfly disc
Sealing filler: Flexible graphite, polytetrafluoroethylene
Flow characteristics: Approximately equal percentage, linear
Operating range: 0–90°
Leakage rate Q: Meets ANSI B16.104 Class IV standards
Applicable temperature: Hard seal version – up to 450°C
Basic error: With positioner – less than ±2% of the full stroke
Hysteresis: With positioner – less than 2% of the full stroke
Adjustability ratio: 50:1
Actuators available: GT, AT, AR, AW series of single- and double-acting pneumatic actuators
Control methods: On/off two-position control, 4–20 mA analog control
Pneumatic hard-sealed butterfly valve – Actuator parameters
Actuator models: GT, AT, AR, AW series of single- and double-acting pneumatic actuators
Supply air pressure: 0.4–0.7 MPa
Air supply interface: G1/4”, G1/8”, G3/8”, G1/2”
Ambient temperature: –30–+70°C
Operation mode: Single-acting actuator: Air-shut type (B) – valve opens when air supply is lost (FO) ； Air-open (K) -- Valve position closes when air is lost (FC); Double-acting actuator: Air-close (B) -- Valve position remains unchanged when air is lost (FL) ； Air-operated type (K) – The valve position is maintained in the FL position when air supply is lost. Accessories such as positioners, solenoid valves, air filters and pressure regulators, hold-down valves, limit switches, valve position transmitters, and handwheel mechanisms can be used. It features a new series of pneumatic actuators, available in double-acting and single-acting (spring-return) types, with gear and rack drive for safety and reliability ； Large-diameter valves use series AW pneumatic actuators with fork-type drive; they feature a rational design, high output torque, and are available in double-acting and single-acting versions. 1. Gear-type dual pistons, offering high output torque and a compact size. 2. The cylinders are made of aluminum alloy material, which is lightweight and has an attractive appearance. 3. Manual operating mechanisms can be installed at the top and bottom. 4. The rack-type connection allows adjustment of the opening angle and rated flow rate. 5. The actuator can be equipped with a telecommunication signal feedback indicator and various accessories to enable automated operation. 6. The IS05211 standard facilitates the installation and replacement of products. 7. The adjustment screws at both ends allow the standard product to have an adjustable range of ±4° at 0° and 90°. Ensure the synchronization accuracy with the valve. Pneumatic hard-sealed butterfly valve
Parts and materials
Part name | Material
Valve body | Cast iron, stainless steel, chrome-molybdenum steel, alloy steel
Butterfly plate | Cast steel, alloy steel, stainless steel, chrome-molybdenum steel
Sealing ring | Multi-layer combination of stainless steel and high-temperature resistant asbestos sheet
Valve stem | 2Cr13, 1Cr13 stainless steel, chrome-molybdenum steel
Packaging material | O-ring, flexible graphite
Performance specifications of pneumatic hard-sealed butterfly valve
Nominal diameter DN (mm): DN50～1200
Nominal pressure PN (MPa): 0.6, 1.0, 1.6, 2.5
Test pressures
Strength test: 0.9, 1.5, 2.4, 3.75
Sealing test: 0.66, 1.1, 1.76, 2.75
Low-pressure airtightness test: 0.5～0.7
Applicable media: Air, water, sewage, steam, gas, oils, etc.
Applicable temperatures: Carbon steel: -29℃～600℃; Stainless steel: -40℃～600℃
Design standards for pneumatic hard-sealed butterfly valve
Design standard: GB/T12238-1989
Flange connection dimensions: GB/T9113.1-2000 ； GB/T9115.1-2000 ； JB78 Structural length GB/T12221-1989 Pressure test GB/T13927-2000 ； JB/T9092-1999 Pneumatic hard-sealed butterfly valves – Eccentric principle: (1) Deviation from the center of the pipeline; (2) Deviation from the center of the sealing surface; (3) Inclined cone shape. When the valve is opened, the butterfly disc comes into contact with the valve seat for a brief moment at the time of closure; by utilizing eccentricity 1 and eccentricity 2, the butterfly disc can quickly disengage from the valve seat, thereby reducing wear on the sealing surfaces. This results in low friction torque and smooth operation of the valve. The eccentric conical surface 3 allows the butterfly disc to pass through the inner hole of the valve seat when the valve is opened or closed, thereby achieving a contact seal. Furthermore, the rotational radius of the conical butterfly valve disc is greater than that at the contact point of the sealing pair; as a result, the disc closes more tightly as the valve is closed, enabling self-locking and preventing the disc from moving beyond its intended position. Pneumatic triple-eccentric hard-sealed butterfly valve (eccentric principle) Pneumatic triple-eccentric hard-sealed butterfly valve (sealing principle) Pneumatic triple-eccentric hard-sealed butterfly valve (eccentric principle) Pneumatic triple-eccentric hard-sealed butterfly valve (sealing principle) Pneumatic hard-sealed butterfly valve Connection dimension diagram D643H Pneumatic hard-sealed butterfly valve (flanged type) D673H Pneumatic hard-sealed butterfly valve (wafer type) D643H Pneumatic hard-sealed butterfly valve (flanged type) D673H Pneumatic hard-sealed butterfly valve (wafer type) Pneumatic hard-sealed butterfly valve Connection dimensions Nominal diameter (DN) Main dimensions Flange dimensions L (overall length) H H1 A 1.0MPa 1.6MPa 2.5MPa Flange Wafer D D1 n-Фd D D1 n-Фd D D1 n-Фd 50 108 43 112 625 245 165 125 4-18 165 125 4-18 165 125 4-18 65 112 46 115 625 245 185 145 4-18 185 145 4-18 185 145 8-18 80 114 46 120 645 245 200 160 4-18 200 160 8-18 200 160 8-18 100 127 52 138 675 355 220 180 8-18 220 180 8-18 235 190 8-22 125 140 56 164 715 355 250 210 8-18 250 210 8-18 270 220 8-26 150 140 56 175 800 355 285 240 8-22 285 240 8-22 300 250 8-26 200 152 60 200 850 250 340 295 8-22 340 295 12-22 360 310 12-26 250 165 68 243 925 250 395 350 12-22 405 355 12-26 425 370 12-30 300 178 78 250 1035 450 445 400 12-22 460 410 12-26 485 430 16-30 350 190 78 280 1070 450 505 460 16-22 520 470 12-26 555 490 16-33 400 216 102 305 1190 450 565 515 16-26 580 525 16-26 620 550 16-36 450 222 114 350 1250 650 615 565 20-26 640 585 16-30 670 600 20-36 500 229 127 380 1290 650 670 620 20-26 715 650 20-30 730 660 20-36 600 267 154 445 1455 850 780 725 20-30 840 770 20-33 845 770 20-39 700 292 165 480 1585 850 895 840 24-30 910 840 24-36 960 875 24-42 800 318 190 530 1700 1250 1015 950 24-33 1025 950 24-39 1085 990 24-48 900 330 203 580 1965 1250 1115 1050 28-33 1125 1050 28-39 1185 1090 28-48 1000 410 216 650 2015 1250 1230 1160 28-36 1255 1170 28-42 1320 1210 28-56 1200 470 254 760 2250 1250 1455 1380 32-39 1485 1390 32-48 1530 1420 32-56 Pneumatic hard-sealed butterfly valve Product selection (1) Valve body parameters: series parameters such as nominal diameter, operating pressure, process medium, application environment, and valve body material. (2) Actuator parameters: actuator type, control method, control signal (4-20mA, 1-5V), and operation mode (air-open, air-close). Please provide as many details as possible for these technical parameters, so that our company’s production team and technical staff can select the most suitable option for you. If you have any questions, you can call us; we will do our best to provide you with excellent service! Related names: Pneumatic hard-sealed butterfly valve, D643H pneumatic triple-eccentric metal-sealed butterfly valve
That’s great. If product promotion is intended, it’s a good idea to create high-quality materials, such as sending product samples and selection guides, or sharing videos that contain technical information or insights from actual usage experiences – these are also very popular.