For valves installed in outdoor valve wells, it is recommended to use concealed stem gate valves. There are the following drawbacks to using a rising stem gate valve:

1. When opening and closing the valve, the valve stem needs to be raised and lowered, occupying a large amount of space. If the pipeline is not buried very deep, the valve well will hinder the opening of the valve. When the valve is opened, the valve well cover will not cover or the valve cannot be fully opened.

2. After switching multiple times, the contact surface between the valve stem and the pressure flange cover leaks more severely, requiring frequent replacement of the packing.

3. If the valve is not frequently opened and closed, a part of the valve stem will be exposed outside the valve body for a long time. In the humid environment of the valve well, this exposed valve stem is prone to oxidation, rust, and death. Once it needs to be closed, it will not be able to be closed. Otherwise, it is necessary to apply lubricating grease frequently. In short, the maintenance workload is large.

Hidden stem valves do not have these problems, the probability of water leakage is also small, and of course, the maintenance workload is also small. For reference only.

The types of gate valves can be divided into wedge gate valves and parallel gate valves according to the sealing surface configuration. Wedge gate valves can be further divided into single gate plate, double gate plate, and elastic gate plate types; Parallel gate valves can be divided into single gate plate and double gate plate. According to the thread position of the valve stem, it can be divided into two types: gate valves and concealed stem gate valves.

When the gate valve is closed, the sealing surface can rely solely on the medium pressure to seal, that is, relying solely on the medium pressure to press the sealing surface of the gate valve towards the valve seat on the other side to ensure the sealing of the sealing surface, which is called self sealing. Most gate valves use forced sealing, which means that when the valve is closed, external force must be used to forcefully press the gate plate against the valve seat to ensure the sealing performance of the sealing surface.