Small Knowledge Points of Valve Performance

The sealing performance of valve referred to the ability in each sealing part of valve to stop the medium to let out. It is the most important technical performance of the valve. There are three sealing parts of valve: the boundary of the headstock piece and two sealing surface of valve seat; the contact between filler and valve rod and stuffing box; the joint of the bonnet and valve body. The first one is called inner leakage, which will affect the ability of valve to cut-off the media. For the type of cut -off valve, inner leakage is not allowed. And the later two leakages are called outer leakage, which makes the medial let out from valve to outside. The outer leakage will cause the loss of material, pollute the environment and even make the accident. As some flammable, combustible toxic or radioactive media, the leakage is forbidden apparently. So the valve should have reliable sealing performance

 

The pressure loss will be caused after the media flow pass the valve, in other words , valve has certain resistance towards the flowing of media, which make the media to consume some energy to over come the valve's resistance. To consider from the saving energy, when we design and manufacture the valve, we should reduce the resistance of valve towards the flowing media as much as possible.

 

Opening and closing speed can be expressed by the time in once opening or closing movement of the valve. Generally, there is no special demand for the opening and closing speed. For some particular working conditions, however, they require fast speed so as to prevent the accident while slow opening and closing speed is needed for some conditions to avoid the water hammer. Therefore, we should consider every situation when selecting valves.

 

It means the sensitivity of valve to makes corresponding reactions towards the parametric variation of the media. As throttle valve, reducing valve and control valve which are the valves to control the medium parameter and some special function valves like safety valve and drain valve, the action sensitivity and reliability are the very important technical performance of them.

 

It means the durability of valve, which with great economic value and it is also the significant technical performance of valve. We usually use the promised sealing requirements of the times of opening and closing of valve to express it, it can be expressed by hours of use.