However, instead of a ball mounted in the valve body a circular disc called a butterfly because the two half circles around the vertical shaft appear like wings. There is evidence that the cv number on certain valve types, such as angle valves. All thermoplastic waferstyle butterfly valves shall be manufactured from pvc type 1, grade 1 astm d1784, cell classification 12454, cpvc astm d1784, cell classification 23447 or glass filled polypropylene astm d4101, cell classification 85580. For the installation, operation and maintenance manual iom see the. F l ow r a t e % cv is defined as the flow in gpm that a valve will carry with a pressure drop of 1. Turning the butterfly disk, to close the valve, blocks the passage of the fluid. Butterfly valve types wafer, lug, double offset and triple offset types. Butterfly valve cv values vary with the disc angle and valve. A control valve may be defined as a valve with a powered actuator that responds to an external signal. Wafer type butterfly valve with sy actuator installation of the shutoff and butterfly valves in open systems the fitting of a siphon is recommended for the purpose of achieving the maximum service life of the butterfly valve the seat should be in the. Butterfly valves have fewer parts and are easy to maintain.
Garlock does not offer rubber or metal valves, so our main focus will be on plasticlined valves. Basic norris butterfly valve body types are slip in wafer valves. The design of triple offset butterfly valve bfv tcbv 28150 class is optimized in such way that the torque of the valve is minimized. This type of valve plug is normally utilized in process control applications. Breakaway torque is the total of the torques resulting from bearing. Valve types and features the three basic functions of valves are. The effective volumetric flow calculated for opening angle 54 is.
Concentric rubber lined butterfly valve 2 piece split body ptfe lined butterfly valve double eccentric high performance butterfly valve triple eccentric high performance butterfly valve dual plate check valve engineering data 04 12 14 17 20 22 valve. The manufacturer shall have produced awwa butterfly valves for a minimum of five years. Valves can be categorized also based on their function. A lugstyle butterfly valve used in dead end service generally has a reduced pressure rating. For rotatingstem valves ball, plug, and butterfly, the torque needed to operate the valve is a summation of two loads. A control valve is comprised of an actuator mechanism that is capable of changing the position of flow controlling element in the valve. Shutoff and butterfly valves for openclose applications and. The advantages, components and application of butterfly. A butterfly valve is a quarterturn rotary motion valve, that is used to stop, regulate, and start the flow. Butterfly valves are produced in sizes ranging from nps 1 dn 40 to over nps 200 dn 5000. Different types of valves with pdf file engineering.
A valve with a circular body and a rotary motion disk closure member, pivotally supported by its shaft. Hello, i had to calculate it some years ago and used awwa c504 if i remember well. The torque required to operate a butterfly valve is dependent upon valve diameter, shaft diameter, bearing friction coefficient, type of seat and seat material, shutoff pressure, velocity, disc configuration, system head characteristics, and piping arrangement. Butterfly valve types wafer, lug, double offset and. The amount of total torque tt required to modulate a butterfly valve disc. The manual valves on the bypass of the control valves were evaluated for globe or butterfly valve selection. It is noticeable that wafer type butterfly valves are much cheaper than globe valves, especially when it comes to exotic materials. Noise reduction in butterfly valve cavitation by semicircular fins and vis ualization of cavitation flow 485 figure 2 shows the test valves. A butterfly valve is a sim ple compact device that is easily coupled with actuators. The vf series butterfly valve product data sheets contain the necessary actuator sizing sheets. The torque required is the maximum of two different calculations, by one side the required to overcome the. Calculating a butterfly valves torque pls help cr4. These factors combine into four kinds of torque that are discussed in the article. This source of power can be manual hand, gear, chainwheel, lever, etc.
A quick opening valve plug produces a large increase in flow for a small initial change in stem travel. The optimised design of triple offset butterfly valve. Metalseated butterfly valves 336 80900 mm asme classes 150, 300. Butterfly valve cv values vary with the disc angle and valve size. The table below can be used to indicate butterfly valves and their flow coefficients at different open or closed positions. Many of the equations used in these sizing procedures contain a numerical. Noise reduction in butterfly valve cavitation by semicircular.
Effect of butterfly valve disc shape variations on torque. However, in highrecovery valves such as ball or butterfly valves, significant. This turning force in a butterfly valve is determined by three factors. Pressure drop across control valve the following figure is schematic illustration to show fluid flow at around port and plug of.
The following formula may be used to calculate bolt length for. Vf series butterfly valve with a cv 496 at 70 rotation weighs only 19 pounds including a va909x series actuator. In addition to controlling the flow, a control valve may be used to shut off flow. Butterfly valve torque is the rotary effort required to operate a value. Butterfly valves are widely used piping components for both regulation and onoff flow control. For example, a lugstyle butterfly valve mounted between two flanges has a 1,000 kpa 150 psi pressure rating.
They can be useful where it is desirable to control mass flow rates into and out of a process such as liquid level control. You can also open the valve gradually to reduce flow. Operating frequency if a butterfly valve remains closed for an extended period of time, then the initial opening of the valve will require above normal torque. The disk, referred to as the butterfly is attached to a rod. Rotary valve selection guide d102550x012 product bulletin 40. The same valve mounted with one flange, in dead end service, has a 520 kpa 75 psi rating. Manufacturers data should always be checked before actual use.
Figures 59 show the geometry, relative proportions and key features for various types of butterfly valves that were tested. Design criteria mss sp68 design mss sp25 markings api609 seat pressure temperature ratingsblowout proof stem asmeansi b16. Guide for norris series 200 and series 285 butterfly valves. Valve maunufacturers supply tables of required torques for their valves. When the butterfly valve is opened all the way, the disc rotates a 14 turn, allowing for a nearly unrestricted passing of the fluid. Noise calculation formula for valves other than 507v and 508v types. Butterfly valves are available in sizes up to 20 in. The vfh type is provided with a doubleeccentricity disc and a spring to reduce the backlash. Butterfly valves types, construction, applications and. Formulas applicable to circulating conditions with no cavitation inside the valve. See complete details on our full line of manual and.
In the chart below, we show the approximate cv value of butterfly valves ranging from 2 to 24 and at various disc angles. Suitable for use with air and nonaggressive gases according to en 437 vf type. The torque varies between manufacturers and styles of valves and i would never try to calculate it with a generic method. Head loss, torque, and cavitation analysis awwa manual m49 coefficients provided by the quarterturn valve manufacturer may be used to calculate the head loss and torque as described in this manual of standard practice, provided that the data are determined on the basis of testing methods described in chapter 5. Keystone figure 9 butterfly valve a resilient seated butterfly valve for general purpose applications features bubbletight shutoff at full pressure rating ptfe lined configuration is drop tight. Normally, they are used in systems where positive shutoff is not required. The amount of total torque tt required to modulate a butterfly valve. Concentric rubber lined butterfly valve 2 piece split body ptfe lined butterfly valve double eccentric high performance butterfly valve triple eccentric high performance butterfly valve dual plate check valve engineering data 04 12 14 17 20 22 valve configurations scale drawing to actual size application this catalog remains the property of ms.
The torque required is the maximum of two different calculations, by one side the required to overcome the seat friction and get it tight, and the other by calculating the hydrodynamic torque produced in the disc at different angles with flow direction plus the friction on upperlower bearings. The flow coefficient cv equation illustrates that the flow rate through a valve q. To adequately cover the variations in disc geometries common in nuclear power plant applications, a total of 25 disc shapes were included in the test matrix. A control valve performs a special task, controlling the flow of fluids so a process variable such as fluid pressure, level or temperature can be controlled. To determine dynamic torque, the following equation is applied. Selecting a butterfly valve instead of a globe valve for. The design of a slim and streamlined disc shape results in low pressure losses and reduced energy costs for the end user.
Flowseal high performance butterfly valves are available in sizes from 2 48 in asme pressure classes 150, 300, and 600 and are available with a diverse range of actuation options. A typical flanged butterfly valve is illustrated in fig. Wafer type nxo holes threaded or clearance j depth of thread on m bolt circle. The saving of energy costs may be several times the initial cost of the valve. Aerodynamic torque characteristics of butterfly valves in. The difference between a lug and wafer butterfly valve.
The actuator selection charts incorporate a 25% safety factor for 2 in. Less expensive valves for nondemanding, nonabrasive, lower temperature applications. A part of a valve trim that surrounds the closure member and may provide flow characterization and or a seating surface. Comparison of butterfly valves with other valves using 100mm diameter tomoe 700g. We recommend butterfly valves to be sized at 600 opening of the valves. A butterfly valve has a disc which is mounted on a rotating shaft. Low leakage when valve is in closed position vfh type provided with butterfly disc stop. A 90 rotation of the handle can completely close or open the valve. To select the correct valve to fulfill these functions properly, an outline of the different types of valves and their features is given below. They are usually manufactured in flanged, wafer, and lug, or singleflange type designs. However, instead of a ball mounted in the valve body a circular disc called a butterfly because the two half circles around the vertical. The advantages, components and application of butterfly valves a butterfly valve is a quarterturn rotational motion valve, that is used to stop, regulate, and start flow. Key words butterfly valve, numerical simulation, flow coefficient, hydrodynamic torque coefficient 1. Fisher rotary valve selection guide emerson electric.
Butterfly valves butterfly valves use a similar principle to ball valves. For valves supplied with amaterial, chainwheel, the. Flow calculations and cv values ball valves, butterfly. Bolt lengths 112 4 12 12 1916 bolt lengths will vary according to thickness of valve, mating. The seat and the disc are the only two valve parts in contact with the medium. Again the orientation of the butterfly determines the flowrate. Design calculations are carried out for triple offset butterfly valve bfv tcbv 28150 class 700mm size and 20 bar based on maximum pressure. Temperature any service that requires the butterfly valve to operate at the upper or lower. The two types of control valves most commonly utilized in the. The valve modulates flow through movement of a valve plug in relation to the ports located within the valve body. Rubber seated butterfly valve, sizes 3 through 20 inches general butterfly valves shall be manufactured in accordance with the latest revision of awwa c504, class 150b and conform to ansinsf 61 and ansi nsf 372. When trying to calculate the correct torque, the following 5 factors should be considered. It may also provide stability, guiding, balance, and alignment, and facilitate assembly. The valve plug is attached to a valve stem, which, in turn, is connected to the actuator.
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