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.

截止閥的安裝與維護(hù)應(yīng)注意以下事項(xiàng)：

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

1.手輪、手柄操作的截止閥可安裝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.手輪、手柄及偉動(dòng)機(jī)構(gòu)，不允許作起吊用。

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

3.介質(zhì)的流向應(yīng)與閥體所示箭頭方向一致。

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

截止閥具有以下優(yōu)點(diǎn)：

The stop valve has the following advantages:

1.結(jié)構(gòu)簡(jiǎn)單，制造和維修比較方便。

1. Simple structure and convenient manufacture and maintenance.

2.工作行程小，啟閉時(shí)間短。

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

3.密封性好，密封面間磨擦力小，壽命較長(zhǎng)。

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

截止閥有以下缺點(diǎn)：

The stop valve has the following disadvantages:

.流體阻力大，開(kāi)啟和關(guān)閉時(shí)所需力較大。

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

2.不適用于帶顆粒、粘度較大、易結(jié)焦的介質(zhì)。

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

3.調(diào)節(jié)性能較差。

3. Poor regulation performance.