As far as we know, the quality of a valve depends on a lot of factors. Here in this article the writer will introduce some factors briefly. Through this article people can get a general idea about the valve.

What comes first is the flow media. When the media flow through the valve, they will generate the pressure loss. In other word, the valve has the resisting force for the flow of the media and the media have to consume the energy for the purpose of overcoming the resisting force. From the perspective of energy conversation, this resisting force should be reduced when people design the valve.

The second factor is the hoisting force. This force is used to turn on or shut off the valve. When the valve is closed, the seal pressure should be formed between the open-close part and the sealing faces. At the same time, the friction force should be overcome. So it is of great necessity to exert the closing force. During the process of opening or closing the valve, the required hoisting force is changeable.

The third factor is the sealing property. The so-called sealability refers to the ability of preventing the media leakage. It is the most important indicator for a valve. There are three sealing parts, namely the joint between the open-close part and the two sealing faces of the valve seat; the joint between the valve spindle and the packing box; the joint between the valve body and the valve cap. The leakage caused by the first kind of sealing parts is called internal leakage. Generally speaking, the valve is not closed tightly. This will have an influence on the ability of cutting off the media. For the shut-off valve, the internal leakage is not allowed. The leakage caused by the last two sealing parts is called outer leakage. The outer leakage will result in the loss of the material and meanwhile will pollute the environment. Sometimes the serious accident will take place. For the inflammable or poisonous media, the outer leakage is not allowed. In a word, it is very important for a valve to have the reliable valve seal.

The fourth factor is the sensitivity of the valve. It means that the sensitivity for the changes of the media parameters. For a lot of control valves, safety valves and steam taps, the degree of the sensitivity is also a very important technical indicator.

Last but not least, it has something to do with the operation life of a valve. It refers to the degree of the durability. It is also an important performance indicator. This operation life has a great economic meaning.