one fixture or two

[Chad Fabry]

The plumbing code states that no fixture may have more than one trap.

Is a two-basin kitchen sink one fixture or two?

[Greg Booth]

Back in the day, when I worked in the Hospital facilities field, DOH surveyors considered multi basin sinks, such as double and triple commercial kitchen sinks as single fixtures.

......Greg

[Scottpat]

One fixture with two compartments.

[Jim Baird]

Takes two faucets to make it two sinks, verdad?

[Marc]

One fixture with two compartments.

Is this what they call a combination fixture?

06' IPC:

1002.1 Fixture traps. Each plumbing fixture shall be separately trapped by a water-seal trap, except as otherwise permitted by this code. The vertical distance from the fixture outlet to the trap weir shall not exceed 24 inches (610 mm) and the horizontal distance shall not exceed 30 inches (610 mm) measured from the centerline of the fixture outlet to the centerline of the inlet of the trap. The height of a clotheswasher standpipe above a trap shall conform to Section 802.4. A fixture shall not be double trapped.

Exceptions:

1. This section shall not apply to fixtures with integral traps.

2. A combination plumbing fixture is permitted to be installed on one trap, provided that one compartment is not more than 6 inches (152 mm) deeper than the other compartment and the waste outlets are not more than 30 inches (762 mm) apart.

Marc

[allseason]

If the lines continue from one sink to the other and then to the dwv then one trap only. I have a two basin sink and the waste comes through the middle of the wall in between the two sink basins. the two sink drains are attached to the stack with a y, so two traps.

[kurt]

It's one of those things......

I think the "single trap thing" means not having two traps in line. I think it's equally fine to have a trap under each basin that join to a single drain, or have both basins drain through a single trap and single drain.

I'm sure there's someone with an ironclad interpretation that says I'm wrong.

To those people, I say it's time to start following baseball statistics or come up with a rendition of the Love Song of J. Alfred Prufrock rivaling that of it's author.

[allseason]

It's one of those things......

I think the "single trap thing" means not having two traps in line. I think it's equally fine to have a trap under each basin that join to a single drain, or have both basins drain through a single trap and single drain.

I'm sure there's someone with an ironclad interpretation that says I'm wrong.

To those people, I say it's time to start following baseball statistics or come up with a rendition of the Love Song of J. Alfred Prufrock rivaling that of it's author.

Yes.

[Brandon Whitmore]

Kurt,

If you are talking about having 2 traps (e.g. one serving each side of a kitchen sink) on one drain arm, then yes, that is improper.

Why it's wrong, I don't know?

[Scottpat]

Kurt,

If you are talking about having 2 traps (e.g. one serving each side of a kitchen sink) on one drain arm, then yes, that is improper.

Why it's wrong, I don't know?

I was told that it is wrong because one side of a sink might not be used and that trap will dry out and then you have the nice aroma of sewer gas entering the area. With a single trap you don't have to worry about that...

[Chad Fabry]

I think it's wrong because a high volume draining quickly through one side can create a vacuum and suck the other side dry.

I wanted to be clear on the intent of the code though before I compelled the builder to change the configuration.

[Brandon Whitmore]

Both explanations make sense to me......... Thanks.

[allseason]

Kurt,

If you are talking about having 2 traps (e.g. one serving each side of a kitchen sink) on one drain arm, then yes, that is improper.

Why it's wrong, I don't know?

I was told that it is wrong because one side of a sink might not be used and that trap will dry out and then you have the nice aroma of sewer gas entering the area. With a single trap you don't have to worry about that...

That could happen with any unused fixture. Think about a house with 9 bathrooms, how much water is getting into some of those traps?

[John Kogel]

I think it's wrong because a high volume draining quickly through one side can create a vacuum and suck the other side dry.

I don't think that will happen if the T or Y is level and there is a vent stack in the wall. Sometimes water will flood the trap arm towards the other sink.

Sometimes a garbage disposer will have a trap and the other sink will have its own trap. Nothing bad happens.

Two vanity sinks will each have their own trap.

[kurt]

I suppose either of those things could happen (maybe the Moon could create a tidal effect), but I still think it's meaningless blather.

Fixtures that don't get used have traps that can go dry. What's new? Does that mean government should require us to install trap primers to avoid meeting one's end like Lord Mountbatten?

I don't think it would be possible to run enough volume through one side of a sink inasmuch as there's flow restrictors making it nigh on impossible to run more than a couple GPM's down the drain. Even if there was a slight vacuum, maybe the other second trap would burp slightly, but imagining it would suck dry is almost comically silly.

Folks that would get worked up about this one are folks that like giant government creating non-issues to enforce.

The main reason it would be wrong is you'd be wasting materials and time installing more traps than necessary.

I think I'll start working on my Prufrock rendition.......

[Richard Moore]

It is rather unfortunate to equate Uncle Louis' assassination with something as mundane as sewer gas but, aside from that, this Kurt chappy's assessment is spot on. A storm in a tea cup. Now, if you will excuse me, I need to Google "Prufrock" while my crumpets are toasting.

[Chad Fabry]

I suppose either of those things could happen (maybe the Moon could create a tidal effect), but I still think it's meaningless blather.

My panties aren't in a wad over the issue, but there's nothing wrong with understanding the code

Fixtures that don't get used have traps that can go dry. What's new? Does that mean government should require us to install trap primers to avoid meeting one's end like Lord Mountbatten?

I don't think it would be possible to run enough volume through one side of a sink inasmuch as there's flow restrictors making it nigh on impossible to run more than a couple GPM's down the drain. Even if there was a slight vacuum, maybe the other second trap would burp slightly, but imagining it would suck dry is almost comically silly.

Our 60 gallon soaker tub empties in under three minutes. I haven't yet done the math but I'm pretty sure that's faster than 2 gpm

Folks that would get worked up about this one are folks that like giant government creating non-issues to enforce.

When one enforces code, one doesn't have the luxury to choose which portions to enforce. Just the other day I made a plumber remove 8 sanitary tees and replace them with combination wyes. It probably took him a full day and, in all likelihood, the tees would have worked just fine for a hundred years. I guess what I'm saying is, what I think doesn't mean shit when I enforce code. There are hundreds of codes that I consider picayune; I'm sure I'm wrong about a few of them.

The main reason it would be wrong is you'd be wasting materials and time installing more traps than necessary.

I think I'll start working on my Prufrock rendition.......

It's been 30 years since I've read the piece, I will revisit it today to figure out wtf you're talking about.

For the record though, I was never worked up over the issue, I just wanted to understand the intent of the rule. When I get worked up over building code you'll know- it's when I analogize home inspection with the works of T.Searns and Dante.

[kurt]

That's the most words I've managed to tweeze out of Fabry in 10 years!

Search up "Prufrock t.s. eliot" at YouTube. You'll get the idea.

Chad, I was imagining you being Mr. Muni, and just pushing buttons seeing what lit you up. [:-dev3]

The intent of the code is just what you imagined, but it's one of those niggling things. Water doesn't move down drains in a slug drop, it "adheres" to the sidewalls of the drain and stack. There's no suction that's going to radiate through the house if there's a vent system.

If some yoyo wants to use two traps, I'd tell him he's a doofus who wastes money and materials and try to educate him, but that's about it.

But then again, I'm not the enforcement officer.

[Chad Fabry]

That's the most words I've managed to tweeze out of Fabry in 10 years!

That's funny- I just read a post I made a couple years ago about the orientation of a Grundfos pump. It was apparent that I cared enough to consider the question and then take the time to compose a thorough, meaningful contribution.

I'm not sure when I traded concise for parsimony. I rather miss being enthusiastic.

I relented today and typed a few words. I wasn't angry, but I couldn't let the regulars think I was your bitch.

[Tom Raymond]

There's no suction that's going to radiate through the house if there's a vent system.

When I bought my house it had a whole house trap and vent just outside the foundation. The new septic eliminated that, and now I have a bathroom that is unvented. I haven't quite figured out the planetary alignment that causes it, but about once a year flushing the toilet will siphon the tub trap. An AAV would fix it, but I can't figure out how to attach it to the S trap on the sink.

If I can't recreate that condition without cosmic intervention, there's no way it's gonna happen with vent.

[Bain]

That's the most words I've managed to tweeze out of Fabry in 10 years!

I relented today and typed a few words. I wasn't angry, but I couldn't let the regulars think I was your bitch.

If you hadn't said something, I certainly would have. I don't want any misunderstandings about whose bitch you truly are.