A wafer type butterfly valve is a type of butterfly valve that is designed to fit between two flanges in a pipeline. The valve is named "wafer" because it is thin and flat, with a wafer-like shape, and is designed to fit between flanges without the need for bolts and nuts.

The wafer type butterfly valve is operated in the same way as other butterfly valves, by rotating a disc-shaped closure mechanism around an axis perpendicular to the flow of fluid. When the valve is open, the disk is turned parallel to the flow, allowing fluid to pass through. When the valve is closed, the disk is rotated 90 degrees, blocking the flow of fluid.

Wafer type butterfly valves are commonly used in applications where space is limited, as they are compact and lightweight. They are often used in HVAC systems, water treatment plants, and the food and beverage industry.

One of the benefits of wafer type butterfly valves is that they are easy to install and do not require the use of bolts and nuts, making them a cost-effective solution for many applications. They are also available in a variety of materials, including stainless steel, cast iron, and PVC, and in sizes ranging from a few inches to several feet in diameter, making them suitable for a wide range of applications.