The Difference Between a Lug And Wafer Butterfly Valve

Butterfly valves are widely utilized in many different applications and have been around for a while. Since their initial introduction in the 1930s, a variety of industries have made use of them. The butterfly valve, which is commonly composed of cast iron, gets its name from the way its disk functions. Butterfly valves come in a variety of forms, however they can be broadly classified as either lug or wafer valves.
 

MORE ABOUT BUTTERFLY VALVES

"Quarter-turn" valves are what butterfly valves fall under. The valve opens or closes when the metal disk that is a part of its construction rotates a quarter of a turn. A rod is linked to the disk, sometimes known as the "butterfly". The disc spins (a quarter turn) when the butterfly valve is fully opened, enabling almost unfettered fluid passage. To lessen flow, you can alternatively gradually open the valve. Fluid flow is stopped by turning the butterfly (disk) to close the valve. This is because, regardless of its position, the disc is always parallel to or perpendicular to the flow, which causes a drop in pressure.
 

LUG BUTTERFLY VALVE

The lug form of the butterfly valve is comparable to a three-piece ball valve in that it allows one end of the line to be removed without affecting the other end. Threaded inserts, flanges, and two sets of lugs (bolts)—which don't require nuts because each flange has its own bolts—can be used to accomplish this. It's also crucial to remember that replacing, cleaning, inspecting, or repairing a lug butterfly valve doesn't need shutting down the entire system—a wafer butter valve would require this.


 

WAFER BUTTERFLY VALVE

The purpose of a wafer butterfly valve is to hold onto a seal to guard against two-way pressure differentials in fluid flow. Stated differently, the purpose of the wafer version of butterfly valves is to maintain a tight seal and protect against bi-directional pressure differential, hence preventing backflow in systems that are intended for unidirectional flow. This is achieved by utilizing a flat valve face on the upstream and downstream portions of the valve in conjunction with a precisely machined gasket and a tightly fitted seal, such as an O-ring.

Main Differences Between the Two Valves

A Wafer butterfly valve and a Lug butterfly valve differ primarily in their respective designs. Wafer butterfly valves are often smaller due to its disc-shaped body, which creates a tight seal between the pipe flanges. Because of its standard sizing, this type of valve may be rapidly and easily placed into existing pipes, even if it requires somewhat more pressure to operate. They are available in any preferred material and connection method, but they are not as strong as lug butterfly valves. A disc-shaped element that regulates the flow of liquids or gases is attached to the body section of lug butterfly valves, which is connected to the pipeline by bolts and nuts. 
Larger pipes benefit greatly from this design's increased strength and resistance to higher pressures over wafer designs; yet, installation takes longer and there are fewer material possibilities available than for wafer valves.

Wafer Vs Lug in Terms of Connections and Seals

The main differences between lug and wafer butterfly valves are their seals and connections. Wafer-style valves provide a tight seal by fitting their disc-shaped body between two pipe flanges. Although these valves require more pressure to operate than conventional butterfly valves, their common size makes installation into existing pipes simple. Because lug butterfly valves are made of two pieces that are fastened together—a disc inside the body that controls flow and a body section with flanges attached to the pipeline via bolts and nuts—installation requires additional hardware. Compared to wafer designs, this shape offers more strength, but there are fewer material alternatives.Because lug butterfly valves produce a tighter seal against higher pressures than wafer types, their sealing performance is also better.
 

Size, Strength, and Diameter Considerations When Installing the Valves

When installing a pneumatic butterfly valve, the diameter, strength, and size of the pipe connection are important factors to take into account. Wafer butterfly valves fit between two flanges rather than being bolted together, which makes them smaller than lug variants and suitable for confined spaces. They are not as strong as lug valves, though, as the latter require more pressure to function. Because lug valves are stronger and more resistant to higher pressures, they are typically needed for larger pipelines. Wafer-style valves are available in conventional sizes that easily fit into existing pipes, while lug styles are typically required for greater diameters. The valve must match the pipe diameter.
 

Installation and Maintenance for Each Type of Valve

Wafer-style butterfly valves are typically easier and faster to install than lug varieties since they only require the butterfly valve to be placed between two pipe flanges; no additional hardware is needed. Wafer style valve maintenance just involves basic tightening, which is accomplished by adjusting the nuts and bolts holding the body of the valve together. However, lug-style butterfly valves need extra gear to be installed, including bolts and nuts, as well as tools to tighten them. Because lug designs have a few more moving parts than wafer designs, they require a little more maintenance. As such, all parts should be checked before use, including the disc seating and bolt lubrication and seal inspection.

Conclusion wafer vs lug butterfly valve

In conclusion, when comparing wafer-style versus lug-style butterfly valves for usage in HVAC systems, there are a number of distinctions to be aware of. Wafer-style valves have the benefit of being able to fit into small locations, being simple to install with little effort, and requiring less maintenance because they have fewer moving parts. Compared to wafer designs, lug-style butterfly valves are stronger, have superior flow rates, and can withstand higher pressures. While lug styles have slightly more moving parts than wafer designs, installation requires additional hardware in addition to tools for fitting and tightening them. Maintenance calls for more involved procedures like inspecting seals, lubricating bolts, and making sure the disc seats properly. When deciding which type of valve is best for a certain application, it's critical to take its specific requirements into account.

Applications for lug and wafer butterfly valves can be found in many industrial sectors, such as waste water management, food processing, pharmaceutical, chemical, and oil. The "Pharmaceutical Quality/Manufacturing Standard" and current good manufacturing practice (cGMP) criteria are often followed during the manufacturing process of the valves used in these industries. In several industries, ball valves have mostly been replaced by butterfly valves. This is particularly true for individuals working with petroleum since they are less expensive and simpler to install. It's crucial to remember that butterfly valve-equipped pipes cannot be "pigged" for cleaning. The technique known as "pigging" involves using tools called "pigs" to perform a range of maintenance tasks.