Connecting to another vent pipe

[Pablo2020]

I am replacing existing drainage and vent 1 1/4 pipes with 1 1/2 and 2"
in the basement, I had to connect new vent 1 1/2 (black color) to washroom downstairs
also running new 1 1/2 plumbing (in the blue color) for tub on first floor
the nearest vent pipe is 6 feet away can i do "U" connection to the vent pipe like it is shown in side view ?

 

[Terry]

Vents can tie back in at 6" above the flood level of the fixtures served.

 

[Sponsor]

 

[Pablo2020]

Thank you for your reply, here is the picture of the area where I am working
in the red this is a 2 inch pipe going from the bathtub connecting to 3" stack
and in the green is the propose vent connection to horizontal vent from the basement bathroom
can I do this ? I do not have option to go 6" above the served fixture,

 

[Tuttles Revenge]

No.. Vents are required to go UP. And as shown in Terrys diagram, the vent needs to connect to a vent from below "6 inches above its flood level"
One reason for this is so that in case your drain clogs, water doesn't just travel through the vent and continue draining. With the vent above the fixture flood level, you will know the drain is clogged because it will flood.

Your tub vent needs to tie in / connect above the tub.