Kitchen Sink drain into main Vent stack

[Steelbuster]

HI, My toilet trap arm drains into a 4" tee below the floor with the main vent stack out the top of the tee. My kitchen sink drain has a 42" trap arm that is tee'd into that 4" vent above the toilet drain tee. Firstly, is that OK?
Secondly, I need to lower that trap arm from approximately 19" above the floor to about 15-16" to accommodate a deeper sink basin being installed. Are there any resrtictions on the height of the kitchen drain where it ties into the 4" main vent stack? If not, do I use a sanitary tee for the connection.
Thanks

 

[Jeff H Young]

sounds good but you are at the far end on trap arm length 42 inches so if your 43 inches you might get called just saying!

 

[Sponsor]

 

[Steelbuster]

Yes, depends on exactly where I measure the trap arm length. Assuming original plumber did it right
Any issues with the sink tie in being below the toilet flood rim or???