It may not of been a back flow but when I was trying to read it just had arrows indicating the flow direction. The writing was on the side towards the foundation.
Maybe the owner (or someone) thinks that a spring loaded check will keep gas from coming back through to the laundry tub? Needs a trap. Laundry tubs drain all type of debris (lint, etc.) that will get behind the seal in a check and prohibit it from closing.
Mike , I have never seen a bottle trap, but my first thought was a drum trap which is not considered sufficient.
Is a bottle trap enough of a water barrier ?
Bob, the answer is depends but probably no. Up to the AHJ as always.
From one of the manufacturers:
Please note that bottle traps (all brands) may not be per code (meaning they may not be legal) in your area.
It would be best to check with your local plumbing code before purchasing and installing them.
Bottle traps are used in many countries as the “standard” trap but not in the U.S.
Must be a version of a drum trap then.
I get these on many inspections , under tubs and upside down so the tub water hits you in the face when you rod from the basement…
Same kind of design is<nt Mike?
Other than the clean out it seems to function the dame.
By the way I have seen 100’s of drum traps not upside down in apartments , where they are usually placed between the tub and toilet.
It is flush mounted to the flloor with a chrome cap.