Wegman valves offers various valves
Rubber lined butterfly valve
All names where usually the same type of butterfly valve design is meant. The shaft is in the is in the middle of the disc and is the center of the rotation of the disc. It’s also in the middle of the valve body and in line with the sealing area.
The disc seals to the rubber liner which is “on” the valve body. It actually presses into the liner.
This “on” needs to be explained as it can be loose, which means it can be replaced when damaged, but it also means it can get off in under pressure (usually called vacuum but it isn’t) applications. I can be vulcanized to the valve body which is understood as high quality and applicable in under pressure applications but there is also the “glued” version.
Typically class 150 (PN16/20) rated, this does not always mean the complete valve can handle this pressure but it’s the body rating.
Usually available in wafer, wafer/lug and lugged.
EPDM, NBR are the usual liner materials.
The body can be Iron or steel and the disc is typically Stainless Steel or (epoxy) coated steel.
A lined (PTFE) butterfly valve is a high corrosion resistant version of the above.
Temperature is limited by the liner material.