What does the arrow on the valve mean?

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The direction of the arrow indicated on the valve body shows the direction in which the valve can withstand pressure; it is often misused by engineering equipment manufacturers as a symbol for the flow direction of the medium, leading to leaks and 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. Suida’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 indicator arrows, the direction of these arrows varies depending on the location of the valve in the pipeline, and it also differs from the flow direction of the medium. For example, at the outlet 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, the arrow is in the same direction as the medium flow. When the valve is installed on a main pipeline, the arrow generally follows the flow direction of the medium. The exact orientation of the arrow depends on the operating conditions and the location of the valve.