The types of stop valves are divided into external thread type and internal thread type according to the position of stem thread. According to the flow direction of the medium, there are straight through type, DC type and angle type. The stop valve is divided into packing seal stop valve and bellows seal stop valve according to the sealing form.

截止阀的安装与维护应注意以下事项：

The installation and maintenance of stop valve shall pay attention to the following matters:

1.手轮、手柄操作的截止阀可安装在管道的任何位置上。

1. The stop valve operated by hand wheel and handle can be installed at any position of the pipeline.

2.手轮、手柄及伟动机构，不允许作起吊用。

2. Handwheel, handle and servo mechanism are not allowed to be used for lifting.

3.介质的流向应与阀体所示箭头方向一致。

3. The flow direction of medium shall be consistent with the arrow direction shown on the valve body.

截止阀具有以下优点：

The stop valve has the following advantages:

1.结构简单，制造和维修比较方便。

1. Simple structure and convenient manufacture and maintenance.

2.工作行程小，启闭时间短。

2. Small working stroke and short opening and closing time.

3.密封性好，密封面间磨擦力小，寿命较长。

3. Good sealing performance, small friction between sealing surfaces and long service life.

截止阀有以下缺点：

The stop valve has the following disadvantages:

.流体阻力大，开启和关闭时所需力较大。

. the fluid resistance is large, and the force required for opening and closing is large.

2.不适用于带颗粒、粘度较大、易结焦的介质。

2. It is not applicable to media with particles, high viscosity and easy coking.

3.调节性能较差。

3. Poor regulation performance.