Regulating valve for regulating the flow of media, pressure and level. According to the signal conditioning parts, automatic control valve opening degree, so as to achieve the medium flow, pressure and level of regulation. Valve sub-electric control valve, pneumatic control valve and hydraulic control valve.
Regulating valve by the electric actuator or pneumatic actuator and control valve composed of two parts. Regulating valves are usually divided through single-seat regulating valve regulating valve and through engine two, the latter having a large flow capacity, unbalanced do small and stable operation characteristics, it is usually especially suitable for high flow, high pressure drop and leakage few occasions.
Cv flow capacity is to select one of the main parameters regulating valve, regulating valve flow capacity is defined as follows: when the control valve fully open, the pressure differential across the valve is 0.1MPa, fluid density 1g / cm3, the hourly flow path adjusting the flow rate of the number of valves, called flow capacity, also known as flow coefficient to Cv, said unit t / h, Cv liquid value is calculated as follows.
Cv flow capacity value according to the size of the table, you can determine the control valve nominal diameter DN.
Regulate the flow characteristics of the valve, is maintaining a constant differential pressure across the valve condition, the relationship between the media flows through the valve relative flow with its opening. Control valve flow characteristics are linear features, such as the percentage properties and parabolic characteristic three. SIGNIFICANCE OF THREE Fluence feature are as follows:
The percentage of relative stroke and the relative flow (1) the percentage of properties (logarithmic) equal percentage characteristic is not a linear relationship between the flow rate proportional to the flow rate change itinerary changes every point in the stroke unit caused by this point, the flow rate variation It is equal. So it has the advantage traffic hours, small changes in flow, flow, then the flow rate changes, that is, different openings, have the same regulation accuracy.
(2) linear characteristic relative stroke (linear) linear characteristic and the relative flow into a linear relationship. Flow changes caused by changes in stroke unit is unchanged. Flow, the flow is relatively small change in the value of traffic hours, the flow rate variation in relative value.
(3) the parabolic nature of the flow is proportional to the stroke by two changes, with intermediate characteristics generally linear and equal percentage characteristics.
As it can be seen from the analysis of the three characteristics of its performance in terms of adjusting to the optimal percentage of properties that regulate stable, regulated performance. The parabolic characteristic off than good regulation performance linear characteristic, may vary according to applications requirements, the selection of any of these flow characteristics.