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Electric regulating valves and pneumatic regulating valves are precision instruments. Even the best things can not be used correctly if they are not installed according to the specified requirements. Especially for new pipes and new valves, many problems will arise during transportation and installation. The correct installation method can ensure the normal operation of the regulating valve, which is also crucial for the later maintenance, maintenance and use.
1. In the initial stage of commissioning and overhauling of the newly installed regulating valve, it is necessary to take measures to isolate or remove the process piping during the purge to prevent the medium from circulating due to clogging of the welding slag, rust, etc. in the pipeline. Smooth, or the valve is too tight in the overhaul of the regulating valve, causing the friction to increase, resulting in the phenomenon that the small signal does not move and the large signal moves too far.
2. When installing the pneumatic regulating valve, pay attention to the air opening and air closing of the regulating valve to prevent the valve from leaking due to the discomfort of the valve stem length.
3. In order to prevent cavitation, the following points should be noted during the original selection and installation: 1) Install the regulating valve at the lowest position of the system as much as possible, so as to increase the inlet pressure and outlet pressure of the regulating valve relatively; 2) A shut-off valve or orifice plate is installed upstream or downstream of the regulating valve to change the original installation pressure drop characteristics of the regulating valve; 3) special anti-cavitating internals can also effectively prevent flashing or cavitation, it It is possible to change the flow velocity of the fluid in the regulating valve, thereby increasing the internal pressure; 4) using a harder-regulating valve as much as possible, because in the event of cavitation, it has certain erosion resistance for such a regulating valve. The grinding performance allows the cavitation to exist under certain conditions without damaging the inner parts of the regulating valve. On the contrary, for the soft material regulating valve, when the cavitation occurs, the inner part of the regulating valve will wear quickly.
4. The regulating valve should generally be installed upright. If it needs to be tilted, it should be supported.
5. The flow direction of the medium must be consistent with the arrow of the valve body.
6. The installation position of the regulating valve should be easy to observe, operate and maintain.
7. The signal tube of the actuator should have sufficient expansion allowance and should not interfere with the action of the actuator.
Control valve selection
Selection of structural form: steam flow control should select single valve seat; large diameter, large flow, low pressure difference should choose butterfly valve, but the leakage is large at this time; when the medium is high pressure, high pressure regulating valve should be selected; Sewage, prevent valve blockage, optional angle control valve; optional three-way control valve for water volume or water temperature adjustment of heat exchanger.
Selection of regulating valve diameter: When using double-position regulating valve, the valve diameter can be directly selected according to the pipe diameter; in other cases, the valve capacity should be determined according to the maximum flow rate of the medium and the valve pressure drop to calculate the flow capacity Kv value.
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