First, as shown in the left figure, the pneumatic butterfly valve is not a standard butterfly valve but an eccentric butterfly valve. The valve stem is not located at the central axis of the disc but is offset upward.

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The left side of the valve is a pneumatic cylinder, and the right side is a damping oil cylinder. The function of the pneumatic cylinder is to control the closing of the butterfly valve. This valve is a fail-open (FO) valve. When the air compressor is running, the logic output (DO) de-energizes the solenoid valve, causing the cylinder to exhaust and the valve to open. This action is achieved through a weighted lever mechanism. The damping oil cylinder includes a throttle valve component on its right side, which reduces the oil flow (the oil path consists of a damping tube and a check valve) to achieve controlled opening. This mechanism slows down the valve during the opening process and prevents significant impact noise during closing.Check Valve

As shown in the right figure, the valve is currently in the closed position. The closing action is driven by the adjustment rod of the pneumatic cylinder, which pushes the weighted lever of the valve. This lever rotates the valve stem to control the valve's opening and closing. When the valve closes, the solenoid valve activates, allowing air into the cylinder. This pushes the adjustment rod, moving the weighted lever and rotating the valve stem to turn the disc to the right. (During this action, the oil path in the damping cylinder only involves the damping tube, while the check valve remains closed.) The valve then closes.Check Valve manufactor

As shown in the right figure, the medium flows from left to right. During forward flow, the lower part of the disc and valve stem experiences greater force than the upper part, resulting in a force that tends to open the valve. Conversely, during reverse flow, the force on the disc tends to close the valve. Therefore, when the medium flows in the reverse direction, the valve functions as a check valve.

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