New and improved for 2009. The latest version of the IPC contains such nifty tidbits as this gem
All backflow preventers having an atmospheric vent (watts 9d et al ) must have the vent piped to a waste receptor by means of an air break or an air gap.
(those of you installing boilers should have a good time with this one)
This includes boiler feeds and those nasty little chrome BFP's they make us put on soda machines.
Feel the Joy Fella's
More to come when the dust dies down.
RPPBFP valves, such as the stainless steel ones used for soda machines, have tappings for an air gap funnel. Others do not and providing one would be difficult or impossible, which is why their instructions specify that they MUST be installed in areas where a discharge would not cause damage.