New to this forum and could not find my answer under a search. 1.) What are the rules ( DWV, ABS for Canada) when using 90 degree sweeps instead of two 45 degree elbows? My senerio is 3 inch main drain stack to a new second story 3 piece bathroom and I have 3 of the 90 degree turns I need to make. I see that plumbers often use a 90 degree sweep at the toilet closet , but after that they seem to stick with always using two 45 degree fitting to minimize the restriction. 2.) Can I use a 90 degree sweep at the horizontal to vertical transition? 3.)Is there any where else (besides venting) that I can use a 90 degree sweep? 4.) And what is the best way to know I have purchased a long sweep? Thanks Greatly!