Found this set up behind/under a laundry sink on a 1970s place. I can see part of it’s an air gap but am lost as to what all the black cap things and other stuff is and what the purpose it? And no, I don’t send out my reports with the crappy blue circles. That’s just what my Windows photo editor has.
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It’s a backflow preventer, normally used for commercial use. The black ports are for testing purposes.
Backflow Prevention Testing | Same Day Service | North East Plumbing
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The left side, that device appears to be a trap primer.
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This is what really confused me… why so many?
It was right through the wall from a high-end commercial type fridge. Maybe it had condensation runoff.
That, I couldn’t tell you. I see similar ports on backflow preventers for lawn sprinkler systems.
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Going off memory, I think the extra test ports indicate a double check valve. It’s also been about 20 years since I watched a backflow preventer test. It is one of the questions I asked.
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Note the “Set Screws” beneath each Gauge Port (black capped). Looking at Kevin’s linked photo, you can see the many different functioning sections for adjustments. Each section gets adjusted for fine-tuning. Not as simple a set-up as one would think.
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The drain pipes above the catch in the bottom there should the same distance away from the catch as the inches in diameter of the catch pipe ?
The air gap is provided above the drain. It’s a brass cup just below the backflow prevention device.
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