I would like to ask about the differences between the upper expansion valve and the lower expansion valve
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The upper expansion valve moves upward, while the lower expansion valve moves downward – I understand that. I would like to ask the experts: what are the differences in the functions of these two valves? Under what circumstances should upward expansion be used, and under what circumstances downward expansion? Is the choice related to the properties of the material? I hope the expert can answer my questions; thank you very much
If both can be used, which one should be given priority?
The difference between the upward-opening discharge valve and the downward-opening discharge valve lies in their flanges: the upward-opening discharge valve typically has a standard diameter, while the downward-opening discharge valve usually has a reduced diameter; moreover, the flange on the side connected to the reaction tank is one size larger for the latter type. Depending on the direction in which the valve disc moves, there are upward-opening discharge valves – as the name suggests, when these valves are opened, the valve disc rises inside the reaction vessel. There are also downward-opening discharge valves; in this case, when the valve is opened, the valve disc descends into the valve chamber. For this reason, it is necessary to use flanges of a higher grade and to increase the volume of the valve chamber. Copper nuts for different types of upward-opening discharge gate valves, as well as copper nuts for downward-opening discharge valve stop valves. The opening and closing stroke varies; accordingly, the installation dimensions differ as well. Upward-opening and downward-opening discharge valves have a shorter opening and closing stroke and thus a lower installation height. The rotary rod design results in the lowest installation height; during the opening and closing process, the plunger only moves in a rotational manner. It relies on an indicator that shows the opening and closing position to determine the state and position of the valve. For the upward-opening discharge valve, the opening torque is such that the valve disc moves upward to open the valve; when it opens, the valve must overcome the force exerted by the medium, and thus the opening torque is greater than the closing torque. The downward-opening and plunger-type discharge valves open as the valve disc moves downward; the direction of this movement is the same as that of the force exerted by the medium, which results in a lower opening torque compared to the closing torque. Although top-opening discharge valves and bottom-opening discharge valves differ significantly from each other, they share common characteristics: the distance between the valve seat and the end flange is minimal, resulting in little material retention; they feature a compact structure and excellent sealing performance. They are used in reactors within the fine chemical, pharmaceutical, and chemical industries, as well as for conveying fine and soft granular media. Using PPL or M sealing materials, it offers superior wear and temperature resistance, making it the ideal product for use in the toothpaste industry and for discharging material from vacuum paste-making pots.
From a mechanical perspective, an underflow valve should be used when there is a stirrer inside the equipment; otherwise, the opening of the valve will interfere with the stirrer
Considering leakage sealing and self-cleaning properties, an upward expansion design is the preferred option. The stirring position you mentioned, expert, should be quite low, right? I haven’t thought about it. Could you explain?
For example, in the case of media with high viscosity and a very small gap between the mixing blades and the equipment housing, there is no space for the valve to extend when it is needed to be deployed in that area
Understood, thank you. It’s indeed something worth considering when making a selection – valuable advice: handshake