How many types of gate valves are there? What are the distinguishing methods?

(1) Classified into two types based on the structure of the gate plate

1. Parallel gate valves feature sealing surfaces parallel to the vertical centerline, meaning the two sealing surfaces are parallel to each other. Within this category, there are double-disc and single-disc types. They are further classified as having or lacking flow-through holes.
2. A wedge gate valve refers to a gate valve where the sealing surfaces form a wedge shape by being angled relative to the vertical centerline. Within this category, there are further distinctions between double-disc gate valves, single-disc gate valves, and elastic disc gate valves.

(2) Classified into two types based on valve stem construction

1. A rising stem gate valve is a type of gate valve where the valve stem nut is located on the valve bonnet or bracket. When opening or closing the gate, the valve stem is raised or lowered by rotating the valve stem nut.
2. A stemless gate valve is a type of gate valve where the valve stem nut is in direct contact with the medium inside the valve body, and the gate plate is opened or closed by rotating the valve stem.