The wafer butterfly valve and the lug butterfly valve
This butterfly Valve comes in different assortments, depending on the usage and need. In the structure of these valves, there are two main styles or designs: the wafer and the lug.
The wafer design is installed in between two pipe flanges. The valve is held in place since the flanges are surrounded by bolts attached to the flanges, which makes dead end service or disassembly of one end of the piping system impossible. The wafer is also the more common one being bought at hardware stores since most salesmen take it for granted that whenever a person is asking for a butterfly valve, he would automatically assume that the customer is looking for wafer type. This valve is designed to maintain an air tight seal against high amounts of pressure to prevent backflow in the system. The best advantage of this is that it is cheaper compared to the next style.
The lug design takes pride in doing what the wafer style cannot do, by providing dead end service. Lug style butterfly valves have threads inserted at sides of the body. The valve is installed between two pipe flanges and each flange has a different set of bolts, which means that they have to be installed using two sets of bolts and no nuts. This kind of set-up allows it to be disconnected at one side while the other side is not bothered. The down side is that when this ball type valve is used in dead end service, the pressure that it can handle is drastically decreased. More products of valves
