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Valve flow characteristics curve and classification
- Mar 13, 2018 -

 Valve flow characteristic means on both ends of the valve differential pressure under the constant condition, relationship between the relative flow through the valve and its opening. Flow characteristic of regulating valve is an important technical index and parameters. It is very important significance in the process making the right selection.

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Valve flow characteristics can be defined as: relative flow accused of medium flow through the valve, and the relative relations between the relative displacements. In general, it can be divided into linear, equal percentage (log), parabolic and quick opening! The specific description and advantages are as below.

 

1.       Linear feature refers to the relative flow valve and a linear relationship with relative opening degree, namely unit opening changes caused by the flow time constant linear characteristic of relative stroke and the relative flow caused by the change of the unit of the travel in a straight line when traffic is a constant flow rate changed, flow relative changes little, traffic hours, the flow change of relative value.

2.       Percentage characteristics (log) refers to the unit opening changes relative flow rate is proportional to the point of relative flow change, the regulator of the amplification coefficient is variable, and it increases with the relative flow characteristics such as percentage of relative trip and no linear relationship between relative flow in the process of every point unit running changes caused by the flow of change is proportional to the flow of this point, the percentage of the flow rate change is equal hours, so it has the advantage of flow changing flow is small, large flow, the flow rate change is big, is also on the different opening, has the same accuracy.

3.       Parabola change refers to the unit of the opening of the relative characteristics of the changes caused by the relative flow at the point of relative flow value is directly proportional to the square root of the relationship between flow according to the schedule of two proportional changes, generally with linear and percentage in the middle of the properties, etc.

4.       Quick opening, flow characteristic is to point to in the opening hour have larger flow, with the increase of the opening, will soon be able to achieve maximum flow, then add the opening, the flow rate change is very small, it is called the quick opening characteristics

 

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Diaphragm valve flow characteristics are similar to the quick opening feature. Butterfly valve flow characteristics is closed to the percentage of the characteristics. Flow characteristics of gate valve are linear features. Ball valves for flow characteristics are the linear in the opening and closing, when the opening in the middle it is similar to the percentage characteristics.

 

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In general, ball valve and butterfly valve usually are not used to adjust, if done adjust, are also in the case of small opening, generally can be classified into quick opening type. And the majority of real for regulating is basically globe valve. The valve head is processed into different shapes, such as parabolic conical spherical, with the curve of different features.