Older laundry tubs drain the washing machine leaving dirt and soap scum stains.
Discharging the rinse water into a standpipe keeps the tub clean. Using an air admittance valve ensures the tub will drain smoothly and gives you a cleanout. And the hanging unit allows for adjusting the height higher or lower, and removes the legs being on the floor.

Some points and tips:
the standpipe should be 30 – 36 inches to prevent water overflow
deburr cut PVC pipe as lint and material will catch to create blockages
glued PVC needs a twist to assure a good connection
use a carbide bit for masonry walls
it is best and easier to drill a smaller hole first, then drill the correct size hole
put the tub’s trap on before the lower plumbing for correct measurements
after connections are handtightened, run hot to check for leaks, then tighten again
the air admittance valve prevents air lock, and sewer gas odor
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