The control valve is one of the types of reinforcement, which finds the widest application in all kinds of industries. This device can be used as a simple temperature controller or as part of a complex process control system in an automatic mode. Regardless of these factors, a very important point is the selection of such a valve.
If the control valve is selected correctly, this will not only achieve optimum control accuracy, but also easily avoid problems such as erosion wear and a high noise level. In some cases, the valve has such a capacity, which is fully consistent with the task to be solved, and in order to reduce the noise level, it is worth giving preference to the types of reinforcement having a larger nominal diameter.
The control valve is difficult to pick up because it is necessary to link a number of requirements, which, in fact, are mutually exclusive. Selecting a valve with a small capacity or with an excessive supply of it can cause significant problems. If the control valve has too high throughput, this results in the fact that it does not provide the proper level of control accuracy. This is due to the fact that the valve stem will move to a small distance (noticeably smaller in comparison with the full stroke of the rod). Errors of this kind often lead to instability of the entire system, as well as to the failure of both the valve itself and the entire drive. Sometimes the control valve is selected so that the pressure drop across the open device is maximized for this particular task at the highest steam consumption. In terms of practice, this means that the valve is selected for differential pressure.
An important parameter that needs to be oriented when selecting a control valve is noise. The valve should be chosen so that the exhaust velocity of the outlet does not exceed 30% of the speed of sound. This parameter is exceeded very often due to the fact that the nominal diameter of the valve is very small, and the saddle thus has a significant throughput. The shut-off valve can have a special design, which allows to significantly reduce the noise level. In such units , the saddle-plunger pair is represented in the form of perforated cylinders, which significantly reduces the noise level, and also lowers cavitation (if the valve is used on a liquid).
The choice of the valve, as it became clear, should be carried out with the obligatory consideration of a considerable set of factors, which significantly complicates this process. The surest way to avoid any problems is to contact a reliable supplier with sufficient knowledge and experience. This will allow him to offer the customer the highest quality products. It is important to pay attention to certain points, among which is worth mentioning: the reputation of the manufacturer, the suitability of the valve for repair, the possibility of changing the throughput or characteristics of the valve, as well as other parameters that affect the usability.