Electric temperature control valve maintenance, accounts for a considerable proportion of the entire regulating valve repair, the proportion valve repair also many, regulating valve for regulating media flow, pressure and level. According to the signal of the control part, the degree of opening of the automatic control valves, so as to achieve the adjustment of the medium flow rate, pressure and level. Regulating valve sub electric control valves, pneumatic control valves and hydraulic control valve. This manual describes the electric control valves and pneumatic control valve two kinds.
Adjust the valve is composed of two parts of the electric actuator or pneumatic actuators and valves. Regulation and is usually divided into the straight single-block and through engine two, which has a large flow capacity, unbalanced Office small and stable operating characteristics, it is usually particularly suitable for large flow, high pressure drop and leakage few occasions.
The flow capacity Cv is one of the main parameters of selectively adjusting the valve regulating the flow capacity of the valve is defined as: When the regulator valve is fully open, across the valve differential pressure of 0.1 MPa, the density of the fluid of 1g/cm3, the hourly flow path The number of flow regulating valve, called flow capacity, also known as flow coefficient Cv unit t / h, liquid Cv value is calculated as follows. copyright dedecms
Flow capacity Cv value of the size of the look-up table, can determine the valves of nominal diameter DN.
Adjusting the flow characteristics of the valve is in the valve pressure at both ends to maintain constant conditions, the medium flowing through the regulating valve relative flow and it is the relationship between the degree of opening. Adjust the valve flow characteristics are linear features, such as the percentage of properties and parabolic characteristic three. Three injection amount characteristics, the following meaning:
(1) the percentage of properties (logarithmic)
The percentage change in flow is equal at every point of the stroke of the traverse unit caused by changes in the flow rate change and this point is proportional to the flow rate of such the percentage characteristic relative stroke and relative flow not a linear relationship,. Therefore, it has the advantage traffic hours, the flow change is small, the flow is large, then the flow changes, that is, in a different degree of opening, having the same adjustment accuracy.
(2) linear features (linear)
The relative stroke of the linear characteristic and the relative flow into a straight line relationship. The flow change caused by a change of the traverse unit is constant. Flow is large, the flow is relatively small change in value, traffic hours, then the flow is relatively large value change.
(3) the parabolic nature
Flows trip proportional changes, general linear and equal percentage characteristics intermediate characteristics.
As can be seen from the analysis of these three characteristics, the percentage of properties for optimal performance in terms of its regulation, the regulation stability, good regulating performance. The parabolic nature of regulation performance than linear characteristic good, according to the requirements of different occasions, the selection of any kind of flow characteristics.
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