Does the control valve have a flow direction of high in and low out?

I guess it’s usually not available, right? All control valves I’ve seen are installed horizontally; those installed vertically seem to have poor flow control, and it’s difficult to maintain a consistent pressure difference before and after the control valve... This is just my personal opinion for reference only; please point out any errors if there are any!

Ugh, people on the second floor didn’t even understand the topic posted by the original poster; it was mentioned that it should go from high to low, not that it has to be installed vertically.

This actually relates to the issue of whether a globe valve is installed in the correct orientation or the reverse orientation. The proper or incorrect installation of a globe valve depends on the valve’s structure and the pressure it is used under; each method has its advantages and disadvantages. Proper installation is commonly used in situations with lower pressures, where the valve’s cover and seat are sealed using flat gaskets. The advantage is that once the valve is closed, the packing chamber is not under pressure, and there are fewer static sealing points ； The disadvantage is that a large closing torque is required, as the sealing pressure between the door core and the door frame is maintained by this closing torque. The medium pressure acts on the door core in a direction opposite to that of the closing torque, resulting in a decrease in the sealing pressure and an increased risk of leakage. An excessive closing torque can easily cause elastic deformation of the door rod, interlocking between the door rod and the copper sleeve, a decrease in the sealing pressure of the gasket between the valve cover and the valve seat, making it difficult to open the valve, as well as leakage due to the poor sealing between the valve cover and the valve seat. Reverse installation is commonly used in high-pressure applications, where the valve cover and seat employ floating self-sealing. Its advantages and disadvantages are the opposite of those of proper installation. The medium pressure acts in the same direction as the self-sealing effect resulting from the sealing between the door core and the door seat, as well as between the valve cover and the valve seat. The higher the pressure, the tighter the sealing, and thus the greater the sealing pressure ratio, leading to more reliable sealing.

Globe valves are forced-sealing valves; therefore, when the valve is closed, pressure must be applied to the valve disc to ensure that the sealing surface does not leak. When the medium enters the valve from below the valve disc, the resistance that the operating force must overcome consists of the friction between the valve stem and the packing, as well as the thrust generated by the pressure of the medium. The force required to close the valve is greater than that needed to open it; therefore, the diameter of the valve stem must be large enough, otherwise the valve stem may bend, a condition known as \"low inlet, high outlet\". In recent years, since the emergence of self-sealing valves, the flow direction of media in globe valves has changed to enter the valve chamber from above the valve disc, that is, from high to low. At this time, under the action of medium pressure, the force required to close the valve is low, while the force required to open it is high; accordingly, the diameter of the valve stem can be reduced. At the same time, under the influence of the medium, this type of valve is also more airtight. There is no clear standard stipulating why stop valves should be designed with the inlet at the lower level and the outlet at the higher level in domestic or international standards; generally, for sizes up to DN100, the inlet is at the lower level and the outlet at the higher level. ! In the domestic and international valve industry, large-diameter valves are commonly designed with the inlet at a higher level and the outlet at a lower level. Secondly, it also does not specify that valves with a certain diameter or larger should be designed with high inlet and low outlet. (Basically, those of DN125 and above, including DN125, are designed with high inlet and low outlet.) In check valves with high inlet and low outlet pressure, they are usually designed with double valve discs (also known as balanced valve discs). There are two reasons for this design: one is to prevent excessive pressure differences from occurring when the valve is opened or closed. Secondly, the stiffness of the valve must be taken into account. A high inlet and low outlet configuration has a significant impact on the valve; typically, for large-diameter globe valves that are not designed with a balanced valve disc seal to handle this configuration, it becomes very difficult to hold the medium in place. Therefore, the installation direction of the valve should first be strictly followed according to the markings on the valve; if there are no markings, rely on experience or consult the manufacturer – do not install it randomly! ! !

The control valve used in vacuum systems should have high inlet and low outlet

There is such an installation! A high differential pressure and low flow rate are the appropriate operating conditions, as this helps to reduce fluid wear on the valve stem and seat; sleeve control valves are generally chosen for such applications. They are suitable for liquid pressure reduction and release processes, and a ‘direct-acting, air-operated’ regulator represents the best solution. A throttling element needs to be added in front of the valve under extremely high differential pressures.

There are both methods of going from a high level to a low one and from a low level to a high one; it depends on the situation in which they are to be used, as well as on the brand and specific model involved. For example, the koso 501G control valve operates with high pressure on the inlet side and low pressure on the outlet side. As for achieving high returns with low initial investments, that’s quite common.

The fourth and fifth floors are described in great detail. Thank you

Of course there is! It is generally to achieve better sealing!

Yes, for example: sleeve valves... it’s quite normal