Special Venting for Island Fixtures

Section 890 Section 890.1600  Special Venting for Island Fixtures a)         Traps for island sinks and similar equipment shall be roughed in above the floor and shall be vented by extending the vent as high as possible, but at least the drainboard height, and then returning it downward and connecting it to the horizontal sink drain immediately downstream from the vertical fixture drain.  Back-to-back island vented fixtures shall meet the requirements of Section 890.1480(b). b)         The returned vent shall be connected to the horizontal drain through a sanitary drainage fitting and shall be provided with a vent taken off the vertical fixture vent by means of a sanitary drainage fitting immediately below the floor and extending to the nearest partition and then through the roof to the outside atmosphere, or may be connected to other vents at a point at least 6 inches above the flood level rim of the fixture served.  Drainage fittings shall be used on all parts of the vent below the floor level, and a minimum grade of ¼ inch per foot back to the drain shall be maintained.  The returned bend used under the drainboard shall be a one-piece fitting or assembly of a 45 degree, a 90 degree, and a 45 degree elbow in the order named. (See Section 890.1340 and Appendix K.Illustration GG.)