I'm putting a food prep sink (for selling at craft fairs)triple basin SS sink in a garage (closed off separate area) and the building dept stated on permit that I had to have an "air gap" at each sink. Only thing I can find on air gaps are the type for dish washers with an inlet and outlet sticking out of the bottom of the air gap. What does an air gap look like with only one opening and where does it attach to the drain??

You can create an indirect drain connection by using a reducing coupling upside down, (larger side up), and leaving a space in between the sink strainer and the reducing coupling of not less than an inch, (check local code), to prevent any contaminated drain water from entering a sink bay where food is being prepared.

Add a clean-out fitting at the end of the run, under either the left or right sink, depending of course on how you're piping it in.

e-plumber
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"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

it is only one sink and needs only one air gap.
tie all 3 bowls into a common drain. run this drain to a trap with a 1" space between it and the trap inlet. you will need to increase the trap inlet to a larger size pipe, so it looks like a big funnel.
around here, they would want you to install a grease trap(interceptor) as well. not to mention, all drains and vents would have to be copper or cast iron (no plastic) as it is a commercial application.

Around here they would require a "floor sink" flush with the concrete so it acted as a floor drain also, with the sink drain hanging above it. Metal drain lines are only required in fire resistant rated buildings.

what hj said except you can make a "funnel" drain like packy said and you should be ok. check with local code enforcement about the grease trap. if you are not cooking food you may not need one

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PLUMBERS "Protecting The Health Of The Nation"

The determining factor would be whether the inspector would allow a funnel drain, or would require a floor sink. Here they would require the floor sink. And it has to be positioned so the trap seal is viewable.

What e said is right .Pipe your sinks all together.Thats called a combination fixture.Run them twords what we in Ga. call a hub drain. Get a bell reducer turn in upside down and stop the sink drain 1 in. above the bell reducer.I am surprised they didn't ask you to run it through an under the counter grease trap to be honest with you .Good Luck!!!

We're all right but each situation and code requirement is different, I've done them, 'all of the above'.

e-plumber
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"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

same here. but i havent seen to many places require a grease trap if no food is being cooked.

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PLUMBERS "Protecting The Health Of The Nation"

you guys have all been a great help and confirmed what I suspected. I assume until I check in more detail on local code, that I install the normal trap after the "funnel" and then the vent. Question now is how far above the rim of the triple sink basin do i have to be before the vent line can turn horizontal?

I don't think there is a code requirement for that. A vent can't join any others until they are 6 inches above the flood rim of the highest fixture.

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"You can't get there from here"
Berry/Buck/Mills/Stipe

the vent can run at any angle from 90 (straight up) to 45deg. if you lean the pipe at more than 45 deg, it is considered horizontal. once you are 6" above the flood rim of the fixture you are venting, you can run the vent flat. (slight pitch so moisture can drain back)

In MN, all food prep, pot, scullery and bar sinks are required to be directly connected to the sanitary drainage system, and each individual fixture branch to such fixtures must be protected by use of a tell-tale drain. A tell-tale drain is a floor drain without a backwater valve.

The general idea is to not only protect the fixture from back-up from other fixtures downstream, but to also prevent the usage of floor sinks and such receptors where food wastes can accumulate: roach buffets.

Yes, codes vary widely.

In fact here, even if it is being cooked, as long as it is served on paper plates a grease trap is not usually required. But when one is, it is usually a very large one these days.

The triple sink is not a factor since the "overflow rim" is the top of the drain that the indirect waste is hanging over, but most codes specify a 42" dimension just in case the plumbing is used for some other purpose some time in the future.

Connecting them directly negates all the safety features that would prevent vermin, dirty water, etc., from entering the sink by way of the drain and contaminating it. In most jurisdictions, ANY SINK that is used for food preparation has to be indirectly connected to the drain system.

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Connecting them directly negates all the safety features that would prevent vermin, dirty water, etc., from entering the sink by way of the drain and contaminating it.

vermin- protected by trap seal
dirty water- will spill out the lower floor drain
etc.- ?

The main difference is to prevent food wastes from collecting in an open environment, as can happen with a floor sink. Collected foodstuffs are a great place for the vermin you describe to hang out in. Backflow from other fixtures will spill out of the floor drain before compromising the sink.

All such sinks in MN also must be installed with 2" wastes, traps and lever-operated strainers (w/ 2" outlets).