Horizontal double wye for two sinks...kosher?

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cab1960

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Is this configuration code (any?) compliant?
 

cab1960

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Why no issue with flow through one drain sucking the water out of the other trap as it flows by (aspiration).....the vent is on the other side of the trap???
 
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Reach4

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Why no issue with flow through one drain sucking the water out of the other trap as it flows by.....the vent is on the other side of the trap???
The traps are those U-shaped parts. The path to the sanitary tee in the wall is/are called trap arm(s). The water stays in the lower portion of the trap arms and the air is in the upper part. To siphon water from the traps, you would need a vacuum in the trap arm.
 

hj

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In "theory" it can happen, but NOT in "reality" because the flow is too slow to create the negative pressure required. BUT, we can cause it to happen in a testing laboratory with our pumps, which is why it is NOT code compliant.
 

Bacon

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Water moves through the trap because gravity is pushing it, not because a vacuum in your lines is pulling it through. As hj pointed out, once past the trap, the water only occupies the bottom half of the pipe and the air in the upper half of the trap arm is more than adequate to prevent "aspiration" before reaching the vent pipe. Could something get blocked and suck the other trap dry? Yes. Could a perfectly placed gust of wind down your roof vent cause the same thing? Yes. Will it? Very unlikely. You are more likely to have a trap evaporate itself dry than to have it aspirated dry.
 

stcondo

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Sorry to bump an old thread, but in the second comment, Terry says "I would lose the deep trap on the right though..". I'm not a plumber, so I want to be sure I understand. Is the suggestion to replace it with a more shallow trap? I assume it still needs a trap of some sort.

Thanks!
 
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