08-34 Grease interceptor venting

Question: 08-34Code Section: 7Date: 29 December 2008OBC 2006 Reference:,

Question: 1. (There is a) grease interceptor and a vent downstream of the interceptor, but (the) question is (there a restriction) to 135º or 225º?

2. The interceptor is not a P(-trap) nor is it siphonic and can’t find anything in the code to clear up the issue.

3. Also (there is) an issue with the vent being more than one pipe diameter from the outlet of the interceptor, is that a no-no also?


1. There are no restrictions listed as to 135 degrees or 225 degrees. These apply only to a fixture trap. A grease trap does not act as a “fixture trap”.

2. The definition of “interceptor” is in Section

3. There is no reference of the vent being one pipe dia. from the outlet. (see Note: The CTC recommends that due to the possibility of the interceptor being siphoned out, fixture vent requirements should apply to the outlet.

Interpretation: Approved at AMES 2009