hydraulic connector

How air is getting into your pressurized hydraulic system?

Air typically enters the hydraulic system through the the pump inlet and, under certain conditions, past the rod seal of a double-acting cylinder.
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But air can also invade the system through joints in pressurized plumbing.
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When fluid travels through a pipe or hose at relatively high velocity – in a pressure line for example, and has to change direction through a tee or elbow, a venturi effect can be created.
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Because the sealing arrangement of the hydraulic connector is designed to withstand positive pressure – but not negative pressure, air can be drawn into the system – even when the plumbing has no apparent leaks.
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If you made a glass model of a pipe elbow and connected a measuring point in the middle of the angle, you would see a negative pressure when fluid passed through the elbow at high velocity.
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And if you looked carefully, you’d likely see air bubbles entering the system through the seal of the measuring connection.
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What it comes down to is use as few sharp angles – tee-pieces, elbows, etc in hydraulic plumbing as possible. a

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Craig Cook

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