05-01 Oil interceptor as fixture trap

Question: 05-01Code Section: 7Date:OBC 2006 Reference:

Question: Does the illustration in the Intermediate plumbing workbook Fig. 5.42 comply with Part 7 requirements?  If not, should we make the trade schools aware that an oil interceptor may not serve as a fixture trap. 

Interpretation: (On. Reg. 403/97) This question is one that will probably go in the history books as the most frequently asked question and although they have been answered as consistently as possible by the past chairs, we have been unable to satisfy the membership because of a difference of opinion as to what the code is saying and what is a proper plumbing design of floor drains and an oil interceptor installation.

Some will argue that the interceptor should not act as the gang trap, some will argue that the gang trap should be in front of the interceptor and some will state that the gang trap should be downstream of the interceptor.                      

For every argument, there are justifiable reasons why one design should take precedents over the other.  Yet every argument meets the code (or at least the intent).  It is imperative that we amend the code once and for all to deal with this issue. If we are permitted to trap the floor drains upstream of the interceptor, we must concede that this scenario creates a bigger hazard than using the interceptor as the gang trap (providing the interceptor is designed to act as a trap).  The trap will intercept flammable substances and sediment and where are we connecting the vent for this trap?

Installing the gang trap downstream of the oil interceptor would be the best design in our estimation in that the plumbing system is well protected and there are no concerns about venting and no concerns about the trap intercepting materials before the interceptor.

However, we are questioned on the interpretation of what the code is actually saying today and although we have our own preferences in design it is our contention that the fig.5.42 in the plumbing workbook meets the intent of                   

Note:  The CTC proposes to amend Sentence by deleting the existing wording and replacing with:

Floor drains that conform to Sentence are not required to be separately trapped and vented when discharging through an oil interceptor provided the interceptor is connected to the sanitary drainage system through a trap.

Can you let us know if you are in agreement with this proposal?