Butterfly Valve DatasheetsFace to face dimensions for full and standard port valves is the same. All ball valves 2" and below are both standard and full port valves. | |||
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A butterfly valve, abbreviated as BTFLV, is a quarter turn valve (90° or less) with a circular disk as its closing element. The standard design has the valve stem running through the disk, giving a symmetrical appearance. Other designs offset the stem. Advantages include less wear and tear on the disk and seats, and tighter shut-off capabilities. When space is limited, sometimes larger valves may use a hand wheel with a gear arrangement. Butterfly valves are rather easy to maintain. These valves are used for gases, liquids, slurries, powders, and vacuum.
There are Two Butterfly Valve Categories
Category A - Manufacturer's rated cold working pressure (CWP) butterfly valves, usually with a concentric disc and seat configuration. Sizes covered are NPS 2 to NPS 48 for valves having ASME Class 125 or Class 150 flange bolting patterns.
Category B - Pressure-temperature rated butterfly valves that have an offset seat and either an eccentric or a concentric disc configuration. These valves may have a seat rating less than the body rating. Sizes covered are NPS 3 to NPS 24 for Classes 150, 300, and 600.
Butterfly Valve Design Classification
Double Offset Butterfly Valve - This valve features the stem center deviated from the center of the disc and valve. With this structure, the valve disc can leave the valve seat quickly, greatly reducing unnecessary over compression and scraping between them. This structure also helps decrease the wearing process and prolongs the operational life of the valve.
Fire Tight Valve - When using valves in a service that may provide fuel to a fire, it is important to ensure that they are fire tight. Typically the seat in a soft seated fire tight valve contains a metal strip that will provide additional sealing should the seat be burnt or melted away. Fire tight valves can be found on fuel gas applications, VRU systems and in other flammable systems.
Flange Style Butterfly Valve - A butterfly valve with a flange on each end. These have a larger face to face dimension than the wafer and lug style butterfly valves and should not be used when there is limited space. These valves connect directly to the flanges by means of machine bolt to each side of the valve. If the valve torque is high or valve operations become too frequen, a manual flanged butterfly valves can be automated if need be.
High Performance Butterfly Valve - A valve in which the stem is not collinear to the disc centerline but rather offset from the center. The use of offset design helps to enhance uniform tight shut-off against the valve seat and also reduce wear due to friction. This valve can be used for shut-off and throttling fluid flow applications. This valve is made to handle different fluids from general fluid flow applications to viscous and corrosive fluids. The corrosive fluids can be gases or steam. High-performance butterfly valves are mostly of large sizes like 60 inch diameter.
Lug Style Butterfly Valve - Lug butterfly valves connect directly to the flanges by means of a lug or machine bolt. Since these are attached directly to the flanges, each length of pipe on either side of hte valve can be removed and replaced independant of the other. Unlike a wafer type butterfly valve, a lug style valve can serve as an end of the line valve. Lug style butterfly valves have the same face to face dimensions as a wafer style butterfly valve. The valves can be used for end of line service but a blind flange is always recommended. The valves are manufactured to be compatible with either pneumatic or electric actuation.
Triple Offset Butterfly Valve - The design eliminates the rubbing between the seat and seal ring through the flow path, reducing seat and seal wear and extending cycle life. They are used in applications similar to gate valves, where a metal seat is required, and tight shutoff and/or quarter-turn actuation is desired. Triple offset butterfly valves can open and close more quickly and can be frequently operated, even if there is an emergency shutoff. This valve has low torque and is recommended for both high and low temperature applications.
Wafer Style Butterfly Valve - Most wafer style butterfly valves are engineered with four holes that align with the connected pipeline. The valve is sandwiched between two flanges. The rubber valve seat creates a strong seal between the valve and flange connection. Unlike lug style butterfly valves, wafer style butterfly valves cannot be used as pipe ends or end of line service. The entire line must be shut down if either side of the valve requires maintenance. Wafer style butterfly valves are manufactured to be compatible with either pneumatic or electric actuation. Disc and seat material should be determined based on application and flow media.
Zero Offset Butterfly Valve - Concentric or rubber seated are other names for the zero-offset design. Zero offset means there is no offset by the stem of the valve. The valve seals via interference along the disc edge at the stem between the disc and the rubber seat.
Optical path length, abbreviated as \(OPL\), is the effective distance that light travels through an optical system after accounting for the optical properties of the materials along its path. Unlike ordinary geometric distance, which measures only the physical length between two points, optical path length also includes the effect of the material's refractive index, which determines how much the material slows the propagation of light. Optical path length is used in wave optics, fiber optics, astronomy, and optical engineering because it determines how the phase of light changes as it propagates through different media. \( OPL \;=\; n \cdot d \) (Optical Path Length) \( n \;=\; \dfrac{ OPL }{ d }\) \( d \;=\; \dfrac{ OPL }{ n }\) Roche limit, also called Roche radius, is the minimum distance at which a celestial body, such as a moon, comet, asteroid, or other satellite, can orbit a much larger body, such as a planet or star, without being torn apart by the larger body's tidal forces. Tidal forces arise because the gravitational attraction exerted by the larger body is stronger on the side of the satellite closest to it than on the far side. If the satellite moves within the Roche limit, this difference in gravitational pull can exceed the satellite's own gravitational force that holds it together. When this occurs, the satellite may become structurally unstable and begin to break apart. \( d \;=\; R_M \cdot \left( 2 \cdot \dfrac{ \rho_M }{ \rho_m } \right)^{1/3} \) (Roche Limit) \( R_M \;=\; \dfrac{ d }{ \left( 2 \cdot \dfrac{ \rho_M }{ \rho_m } \right)^{1/3} }\) \( \rho_M \;=\; \dfrac{ \rho_m \cdot d^3 }{ 2 \cdot R_M^3 } \) \( \rho_m \;=\; \dfrac{ 2 \cdot \rho_M \cdot R_M^3 }{ d^3 } \) The Roche limit is not a fixed distance applicable to every system. Instead, it depends on the sizes and densities of both the primary body and the orbiting body, as well as the physical properties of the orbiting body. A satellite with a lower density generally has a larger Roche limit because its self-gravity is weaker and therefore more easily overcome by tidal forces. Conversely, a denser satellite can survive closer to the primary because its stronger self-gravity better resists tidal disruption. An important applications of the Roche limit is in explaining the formation and persistence of planetary ring systems. Material orbiting within the Roche limit of a planet is generally unable to accrete into a large, self-gravitating moon because tidal forces continually oppose gravitational assembly. As a result, particles remain dispersed, producing rings such as those surrounding Saturn. Many of Saturn's bright main rings lie within or near Saturn's Roche limit for icy material, consistent with this theory. Similar principles apply to the ring systems of Jupiter, Uranus, and Neptune, although the details of ring formation and evolution involve additional processes such as collisions, resonances, and interactions with shepherd moons. \( d \;\approx\; 2.44 \cdot R_M \cdot \left( 2 \cdot \dfrac{ \rho_M }{ \rho_m } \right)^{1/3} \) (Roche Limit) \( R_M \;\approx\; \dfrac{ d }{ 2.44 } \cdot \left( \dfrac{ \rho_m }{ 2 \cdot \rho_M } \right)^{1/3} \) \( \rho_M \;\approx\; \dfrac{ \rho_m }{ 2 } \cdot \left( \dfrac{ d }{ 2.44 \cdot R_M } \right)^3 \) \( \rho_m \;\approx\; 2 \cdot \rho_M \cdot \left( \dfrac{ 2.44 \cdot R_M }{ d } \right)^3 \) It is important to distinguish the Roche limit from other gravitational boundaries. The Roche limit concerns whether an orbiting body can remain gravitationally intact against tidal forces. It does not determine whether an object remains gravitationally bound to a planet. This question is addressed by concepts such as the Hill sphere or the sphere of gravitational influence. Likewise, crossing the Roche limit does not necessarily mean an object is instantly destroyed. The process of disruption can occur over time and depends on the object's physical properties, orbital trajectory, rotation, and internal structure. The Roche limit is a basic concept in celestial mechanics because it defines the region around a massive body where tidal forces become strong enough to overcome the self-gravity of an orbiting body. It helps understanding the stability of moons, the origin and maintenance of planetary rings, the tidal breakup of comets and asteroids, and the evolution of close-orbiting celestial systems. Orifice plate beta ratio, abbreviated as \( \beta \) (Greek symbol beta), also called beta value or beta coefficient, a dimensionless number, is the relative size of the orifice opening compared to the pipe diameter in which it is installed. The beta ratio is important in flow measurement applications using orifice plates because it affects the accuracy and performance of the measurement. The beta ratio determines the shape of the flow profile downstream of the orifice plate and influences factors such as pressure drop and flow coefficient. \( \beta \;=\; \dfrac{ d_o }{ d }\) (Orifice Plate Beta Ratio) \( d_o \;=\; \beta \cdot d \) \( d \;=\; \dfrac{ d_o }{ \beta }\) Typically, orifice plate installations aim for a beta ratio between 0.2 and 0.8. A beta ratio of 0.2 means that the orifice diameter is 20% of the pipe diameter, while a beta ratio of 0.8 indicates that the orifice diameter is 80% of the pipe diameter. Choosing an appropriate beta ratio depends on factors such as the desired measurement accuracy, the flow conditions, and the specific application requirements. It's worth noting that different beta ratios may require different correction factors and equations to accurately calculate the flow rate through the orifice. These correction factors take into account the beta ratio and other parameters to provide more precise measurements.
Millimeter per Square Second
Millimeter per Square Second Conversion Table Multiply By To Get
0.1
centimeter per square second
0.003278551
foot per square second
0.0001019
acceleration of gravity, g
0.0010
meter per square second
0.00223537
mile per hour second
1
millimeter per square second
Optical Path Length
Optical Path Length Formula
Symbol
English
Metric
\( c \) = Optical Path Length
\(ft\)
\(m\)
\( n \) = Refraction Index
\(dimensionless\)
\(dimensionless\)
\( d \) =Geometric (Physical) Path Length
\(ft\)
\(m\)
Roche Limit
Roche Limit Ridgid Body Formula
\( d \;\approx\; 1.26 \cdot R_M \cdot \left( \dfrac{ \rho_M }{ \rho_m } \right)^{1/3} \) (Roche Limit)
System
English
Metric
\( d \) = Limit Distance from the Center of the Primary Body
\(mi\)
\(km\)
\( R_M \) = Radius of the Primary Body
\(mi\)
\(km\)
\( \rho_M \) = Density of Primary Body
\(lbm \;/\; ft^3\)
\(km \;/\; m^3\)
\( \rho_m \) = Density of Satellite Body
\(lbm \;/\; ft^3\)
\(km \;/\; m^3\)
Roche Limit Fluid Body Formula
System
English
Metric
\( d \) = Limit Distance from the Center of the Primary Body
\(mi\)
\(km\)
\( R_M \) = Radius of the Primary Body
\(mi\)
\(km\)
\( \rho_M \) = Density of Primary Body
\(lbm \;/\; ft^3\)
\(km \;/\; m^3\)
\( \rho_m \) = Density of Satellite Body
\(lbm \;/\; ft^3\)
\(km \;/\; m^3\)
Orifice Plate Beta Ratio
Orifice Plate Beta Ratio formula
Symbol
English
Metric
\( \beta \) (Greek symbol beta) = Orifice Plate Beta Ratio
\(dimensionless\)
\(dimensionless\)
\( d_o \) = Orifice Opening Diameter
\(in\)
\(mm\)
\( d \) = Pipe Inside Diameter
\(in\)
\(mm\)
Butterfly Valve Advantages and Disadvantages | |
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