I inspected a newly built house that just been sold to my client . The kitchen was just put in a week ago. I am not sure if this is an s- trap . The question is if there is a vent in the wall would this still be considered an s-trap . I would think they had a rough inspection done.The sink is on an exterior wall.
I believe I recall reading somewhere that there needs to be 4 inches of straight pipe before turning down to keep it from being an S trap. I looks to me like it is here. Also since it drains into a larger diameter pipe, I would think the probability of siphoning would be small if it were. Run the water a little while, and then take a wiff of the drain after you turn it off. If you smell sewer gas, then it is siphoning and you’ve got a problem. (I don’t think you will.) Just my 2 cents…and my gut feeling.
It is not…
Thanks for the reply
Marks gut is right. 
The minimum trap arm length should be 2x pipe diameter.
Must be a close relative;:mrgreen:
