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Does the arrow on the valve body indicate the flow direction or the pressure resistance direction when the valve is closed? Please enlighten me, sir. Some articles state that the arrow direction indicated on the valve body shows the direction in which the valve can withstand pressure; engineering equipment companies often use this as a symbol for the flow direction of the medium, which can lead to leaks or even pipeline accidents ； The pressure-bearing direction refers to the direction in which pressure is applied to the valve when it is in a closed state within a piping system; the arrow on the valve body indicates this direction. If installed incorrectly, leakage issues may occur as a result of the valve not sealing properly. Sudar’s soft-sealed ball valves generally provide two-way sealing, and arrows are not usually indicated on them. Metal hard-sealed ball valves can also achieve two-way sealing, but their sealing performance in one direction is still better; therefore, arrows are used to indicate the direction for which the valve is designed to withstand pressure. It is advisable to consult the customer’s opinions first. For hard-sealed butterfly valves equipped with indication arrows, the direction of the arrow relative to the flow direction of the medium varies depending on the location within the piping system. For instance, at the discharge end of a water pump in a pump room, the arrow on the valve body points in the opposite direction to the flow of the medium; at the inlet end of the pump, however, the arrow aligns with the flow direction. When installed on a main pipeline, the arrow generally follows the direction of the medium flow. Ultimately, the exact orientation depends on the operating conditions and the specific installation location.