I have a restaurant client that was recently instructed by the health department to install an air gap in a sink drain. This drain was in existence as a solid run for 15 years. The change was performed by their internal equipment maintenance guy.
Now, the problem is that when the water flow stops up at all, water pours from the air gap all over the floor. I know that this is exactly why the air gap is there, to keep water from backing up into a basin potentially full of food products.
The air gap being utilized is simply a break in the drain line and now the top line drops through the air into a funnel catch atop of the bottom section of drain line. The level of this air gap is below the bottom of the basin.
I am including a pic of the current arrangement.
any better ideas?
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I refuse to accept that there are limitations to what we can accomplish. Pete Draganic
Take life as a test and shoot for a better score each day. Matt Garcia
Edited 6/3/2009 12:03 pm ET by PeteDraganic
Replies
As a plumbing inspector, I deal with this all the time, and what I suggest is that you install some kind of an orifice, or flow restictor, in the sink drain, before it gets to the funnel drain.
It could be done by simply reducing the drain connections on the sink tailpieces (vertical) to 1-1/4" . The vertical location of the reducer will give less problems with clogging than doing a reducer on the horizontal portion. You could even install 1-1/4" tailpieces directly onto the sink strainer, using a 1-1/2" x 1-1/4" poly gasket.
This is assuming that the 2" p-trap and drain line will flow freely enough to handle even the flow from an 1-1/4" sink drain. Otherwise, you'll have to reduce the outflow even more, with the ever-present risk of having the orifice plug--so you need to make an arrangement whereby the orifice can be cleaned easily. It's a pain, similar to the flow restrictors that come with floor-standing grease traps.
So if reducing the outflow of the basin causes water to back up then it would not a concern because it is not from the sewer?I suspect the drains along the way in the ground are probably obstructed to some degree, knowing what goes down them regularly.... which may be contributing to the flow problem.could a reservoir at the bottom drain help in allowing a place for excess flow to collect? Perhaps some of the problem is simply that the water from top drain hits bottom drain oddly and there is a loss of smooth flow from A to B causing a backup... so it would need something to help compensate perhaps?
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I refuse to accept that there are limitations to what we can accomplish. Pete Draganic
Take life as a test and shoot for a better score each day. Matt Garcia
There are better fixes than what I suggested--all it takes is money.
If the job had been done right in the beginning, there would be a floor sink with a 3" trap to receive the sink drainage, but that's big $$ now.
A larger funnel for the receptor, and a better-aimed outlet from the sink will help some.
Snaking the drain line will help some.
Reducing FOG-fat oil and grease-in the waste water will help some.
Good,reliable kitchen help is also a big plus, but employee turnover is the constant bane of the food service industry, and the poorest-paid people are the ones who'll mostly use the sinks--just when you get them trained, they find a real job.
Cheapest fix if your not going to get a clean snake job and or video inspect to verify main drain isn't going to be the weak link after correct air gap install;Install air gap to satisfy DOH inspection, chances are they won't run the water long enough to stop up as long as hot water comes to temp fast enough for them to check. Than remove and return parts.Don't think they'll fill the sink since I think strainers/stoppers are actually illegal to have present in this circumstance.
Well, the manager did ask "while you have the tiles up can't you just run another floor drain over here from the one over there?" I am replacing 15 or so tiles in a straight line where a floor joint is transferring a crack through the tile.
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I refuse to accept that there are limitations to what we can accomplish. Pete Draganic
Take life as a test and shoot for a better score each day. Matt Garcia
What's below this? Would it be possible to tie in to the line lower, like in the basement? Getting a bit more head from the waste flow may help keep it moving better.
Also, what rdesigns said. Reducing the outflow may keep the flow rate low enough so that the main line can keep up with the sink. If possible, put the restriction at the end of the sink drain horizontal line so draining more than one tub at once would not overload the main drain. (Note that that may not be legal, since it may cause one tub to backup into the other(s) -- if that's not allowed, you'll just have to train the users not to pull more than one tub plug at once.)
If that doesn't work, fix the main line so it drains better -- but you already knew that and the owner doesn't wanna hear it, I'm sure.
Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.
no basement.. building is on slab.
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I refuse to accept that there are limitations to what we can accomplish. Pete Draganic
Take life as a test and shoot for a better score each day. Matt Garcia
Then you're back to fixing the cause for the slow main drain. ;-(Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.
Rdesigns idea sounds like it might work. When does it overflow? When the sinks are emptied?
I would also have a regular maintenance procedure to make sure the drain is clear.
One other thing I've seen is to elevate the sinks and put a step in front of them.
I don't know if this would be considered a safety violation because of the step.
There are drain cleaners that are supposed to eat up clogs. They can be used on a regular basis.
Will Rogers
I think they overflow during regular use of the faucet to prepare food.
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I refuse to accept that there are limitations to what we can accomplish. Pete Draganic
Take life as a test and shoot for a better score each day. Matt Garcia
I did maintenance in a 45 unit apartment and it was sometimes hard to figure out if the tenant was causing the problem.
Restricting the flow out of the sinks would be cheap.
Putting some biological cleaner down the pipe on a regular basis would be cheap also.
I did that in some of the apartments that had drain problems I couldn't fix with a snake. I can't say the cleaner did the trick. but it was cheap.
If there is a removable strainer for the sink drain it might help with what is put down the drain. It would change the habits of the sink users.
I'm just thinking of inexpensive fixes.
In the apartments some of the time it was the tenants that had bad habits we tried to change. People tend to be embarrassed about stoppages. Or they don't want to except blame because someone shamed them in the past for it.
The sink strainer and the restriction of the waste could change their habits without any lectures from you. they would learn to just be more carefull.
"There are three kinds of men: The one that learns by reading, the few who learn by observation and the rest of them have to pee on the electric fence for themselves."Will Rogers
Edited 6/3/2009 1:47 pm by popawheelie
By the picture that trap and piping is leaning the wrong way and is not secured. Straighten it up and you don't have an air gap. Looks like there are mutiple bowls tied together; a no-no where I'm from. You have a mess on your hands, I don't see how to resolve it without major work, sorry.
That's a new one on me...up till now I'd always thought "air-gap" was used on water supply lines not drain lines. Proper venting for a drain line - YES - but "air-gap" on a drain - NO!!!
That set up looks like the most bogus that I've ever seen ...IN a restaurant no less. Does the inspector have an answer for potential contamination of the food prep area floor with sewage???
An appeal to higher powers seems to be needed here.
[EDIT] Never mind...sec 801.2.3 Just out of touch but not out of sight!
Edited 6/3/2009 7:37 pm by woodway
Air gaps can be and frequently are required on drains for food prep or dish washing. Especially on a multiple bowl configuration. The reason is that if one bowl is allowed and designated for washing, they (DOH) dosen't want a plugged drain backing into the secondary or third bowl used for hand sanitizing or food prep. The pictured configuration may appear out of the ordinary because lots of times a floor drain is used as the air gap, a little more inconspicuous than the picture here. Questions about "sewage" or drain water on the floor are null to the DOH because they further require there be no open storage within, I think 12" of the floor. That way no flooded floor or mop water contact food prep or food items.
Good points. When I was in high school , I worked the evening shift (4 to 11 PM) in a restaurant and I can't tell you how many times we washed the floor mops out in a stainless sink. Was it a food prep sink? Don't know but odds are I'll bet it was used once in awhile. How many teenagers are working in food kitchens today that aren't aware of cross contamination???I'm not eating in any more restaurants...Hep C for everyone.I reread my personal UPC copy and now I'm back up to speed regarding food prep sinks and potato peelers.
"I worked the evening shift (4 to 11 PM) in a restaurant and I can't tell you how many times we washed the floor mops out in a stainless sink."
That again is a good reason for dumping the sink into an on floor mop basin.
An "air gap" is the physical vertical break.
The distance between a spout & the bowl or as in Pete's pic the gap between the sink drain & the funnel.
"That's a new one on me...up till now I'd always thought "air-gap" was used on water supply lines not drain lines."Don't you have an air gap on your kitchen sink for the dishwasher drain line? BruceT
My air gap on the dish washer is in place and working fine.
Re: air gaps on drain lines.
If you look at this issue from the viewpoint of the Health Department, a kitchen sink with a directly-connected drain (no air gap) is not really different than a toilet bowl. Yes, you may have flushed or otherwise cleaned out the bowl of the sink, but the p-trap is just below, filled with potentially bad bacteria from the raw chicken, etc. that you just rinsed in the sink.
In other words, the direct connection makes a bridge for bacteria from the p-trap and the drain downstream.
Air gaps on supply lines, as you know, are common and needed to prevent contamination of the supply water from a submerged outlet. A good example of a submerged outlet is the old-style bathtub faucets that had the spout located below the flood-rim of the tub. Codes for decades have prohibited them.
Up here in Canada, we must all be ready to die from food poisoning. No air gaps on drains here.
And the arguement about contaminated traps really doesn't hold, your resi sinks are direct connection, yes?
Really?
I thought you guys went by the UPC up there.
Food prep sinks, & dishwashers must drain indirectly. Residential does not have that protection written into the code, except dishwashers.
Air gaps are required here only on commercial sinks used for food preparation, not commercial ware-washing sinks or residential sinks. This holds true for both the International Plumbing Code and the Uniform Plumbing Code.
Canadians are just tougher all the way around, but my guess is that many, maybe most, parts of Canada have the same requirement for air gap drains on commercial food prep sinks.
You point out some very valid concerns. I haven't reviewed my own copy of the UPC for some time but after reading about "air gap" in waste lines for food prep sinks and equipment, I was brought up to speed once again. In fact, I had long ago highlighted this very section of the code but forgotten I had even read it. That's part of the value in visiting these forum pages, topics are brought up constantly and anyone grounded in construction can read, recall and or review current code to keep themselves current with present day building standards.
Pete, like others have stated you can restrict the floor, or use a tank that has a larger surface area to receive the discharge from the sink.
we use sediment interceptors like this TANK .