Double quarter (1/4) bend?

I have a question about using a double quarter bend when hooking up a kitchen sink (you know...where the drains for each of the two sinks meets in the middle and then drops down into the p-trap via the double quarter bend). I have known about this type of installation of a kitchen sink drain, but I have never been forced to use it.

I am wondering if anyone knows of any benefits or disadvantages to using the double quarter bend installation method over the traditional method?

thx

A double 90 is not used here. I have seen them used only on vents. A double wye is used here.

It sounds like you're speaking of the center outlet tubular waste. I don't like them because I consider them less stable than end outlet, and I'll usually modify something else rather than use them. But that could be my own bias.

Thanks for the reply kordts. I have checked and the double 1/4 bend fitting is allowed here, and I know that that connection is still used from time to time. I have never used it before, but I am now in a situation where I must use one instead of a traditional hookup or a double wye and 45s because of height restrictions.

Oh well, anyways, if anybody else has experience with using the double 1/4 or even the double wye connection and can offer any insights into the advantages or disadvantages (if any even exist), I would like to learn

Thanks for the reply Herk,

That looks very similar to what I am talking about, except the tee in the middle. The double quarter bend is a dwv fitting and has the two ends sloping inwards like as if it's a double wye and a 45 on each end all joined into one fitting. Sorry I couldn't find a picture of it except in a catalog.

fitting

A double, or twin, elbow is typically the same as two short turn elbows joined back to back. I have never seen anything, even a picture, of the fitting you are describing. One disadvantage of a standard double elbow compared to a center outlet waste is that it has no baffle to direct the water down to the trap as opposed to going straight across and up into the other sink basin.

hj said:

A double, or twin, elbow is typically the same as two short turn elbows joined back to back. I have never seen anything, even a picture, of the fitting you are describing. One disadvantage of a standard double elbow compared to a center outlet waste is that it has no baffle to direct the water down to the trap as opposed to going straight across and up into the other sink basin.

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I am puzzled here, isn't a double elbow and a center outlet waste the same thing? A double elbow like you describe looks very similar to the center outlet waste shown in the picture that Herk was nice enough to provide. And on that note, was exactly points the water down into the drop in that center outlet waste since it just looks like a non-dwv tee on its side to me.

Just so nobody things I am crazy, I ripped a picture of the fitting I have been blabbering about so all can see what I am talking about heh. As you can see in the picture, the fitting is a dwv fitting and both ends are actually curved down into the drop to the p-trap. I don't see this when using the center outlet waste shown in the picture above, but maybe I am wrong?

thx all!

i am curious too.

I'll bet you'll get far more responses using terms
"center outlet" (and "end outlet")
"tubular waste" and
"continuous waste"
in search engines and with people.

But now that you've posted that "Cross Bend" or whatever it might be called, I'd like to know more about it too.

In the "center outlet" continuous waste there is a BAFFLE (a divider) in the middle that you cannot see from looking at a picture of its exterior.


david

The double quarter bend would not be allowed for a sink waste, because, as mentioned above, it does not have the baffle in the tee. The code seems a bit vague on this, but your double ell wouldn't be right. One of the things inspectors usually check is the type of tee in the kitchen drain. The one I pictured above has a baffle between the two sides that the double ell does not have.

"405.4 Approved wye or other directional type branch fittings shall be installed in all continuous wastes connecting or receiving the discharge from food waste disposal units, dishwashers, clotheswashers, or other force discharge fixtures or appliances. No dishwasher drain shall be connected to a sink tailpiece, continuous waste or trap on the discharge side of a food waste disposal unit." (emphasis mine)

The above is why there is an inlet for the dishwasher on the "inlet" side of a disposer. I don't see anything in the code that prohibits the double wye for two strainers, but there may be something somewhere else in the code, and an inspector would probably reject it. On the other hand, commercial sinks are usually plumbed with solid pipe and fittings rather than tubular.

Ok, I have checked into my code and it doesn't say anything about being restricted to using a baffled tee, but the fancy picture in the appendix showing acceptable multi-sink drain connections actually shows a fitting that looks pretty identical to a double 1/4 bend rather than a baffled tee, so I think I'm good.

I was in a hardware store today and actually saw a baffled tee center outlet drain system, and I saw how the baffle was placed in the tee to separate the flow from each side. While I do think this setup definitely would minimize or outright prevent drainage from one sink to backup into the other sink, I also see that the baffle restricts the rate of flow from each sink.

I also was able to track down (after visiting 3 suppliers) the mysterious double 1/4 bend fitting, and I have taken some pretty pictures so that everyone can enjoy! I like the double 1/4 bend because it seems to direct the flow from each side nicely without restricting the flow anywhere near as much as the baffled tee. Now I do realize that it does have a greater potential to back up into the other sink, but it also has much less of a chance at getting clogged like a baffled tee would; or so is my opinion. I should also say that this fitting set me back 10 bux at the wholesaler! Which is probably the price for the entire baffle kit heh! Even they said that they had rarely seen or sold one. Anyways, take a look at the pictures people; I'd like to hear any comments on the fitting. I don't think I will ever come across another installation that will require me to use the double 1/4 bend again soon, but it's always nice to learn as much about this installation method as I can in case I have to use it again!

Would never pass in my state (For one, it's black, two, it's not baffled)

The reason for baffled tees is to prevent waste matter from travelling to the other side of the pipe, souring/laying there until water is directed through that drain.

To rely on the end user to perform that necessity to prevent the souring/smell/foul odors of waste is not good because of how plumbing systems are designed.

SO,

When you drop cream corn in the disposal along with the baby carrots and maybe some peas!......some of that is going to cross/shoot right over to the other side.

IF you forget to run water in that drain opposite of the disposal....that is waste that hasn't reached the trap to protect from foul odor.

There was a reason why code implicated baffled tees, to solve a problem like I stated.

Your system will now have to be "maintained"....unlike the original designed already protected from.

Even without a disposal......IF you have a dishwasher in this equation.....when you dump the water out of one bowl.....the momentum of fluid dynamics is going to send wastewater to the other side, contaminates that should only of flowed one direction.....away from the area it first left.

RUGGED said:

Would never pass in my state (For one, it's black, two, it's not baffled)

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Really, you guys aren't allowed to use ABS in your DWV systems? That's interesting; is there any particular reason why? I guess that means you only use PVC? We can use either, but it's standard to use ABS here.

You do raise a valid point about the possibility of resultant odors. I will definitely continue to consider using a baffled tee, although I must admit I am leaning towards the double 1/4 bend

Just in trailers, that's it.


Trying to find ABS pipe and fittings is non-existent here.

When the big box stores came here years ago they introduced it to the area but soon enough they saw the sagging sales....and the pipe was just garbage even before the stuff was installed.

Very poor quality, wasn't even SCH40 on the pipe, just the fittings. I do know that it's common in other areas across the states.

Even if I lived in your area, I'd still baffle it since I can't take a chance on ever having a callback. To each thier own in thier very own home.

We cant even find ABS in any BB store or supply house.Not allowed by code
in our area.Must have ASTM#to pass.Am I correct Rugged.
ASTM 1745? #might be wrong.

abs

In this area you would have to do a major search, (or buy from ACE hardware, HD, etc.), to find a PVC drain fitting. If you use that fitting, be sure you make some provision for taking the drain system apart when cleaning is required.

In my area, ABS is common and PVC is rare. Not sure what problems other have with it, but the many hundreds of houses I've plumbed with it, including my own, have no problems, beyond things you'd expect like bad pipe or improper installation. I went back on one pipe that I'd installed when plumbing a new house 26 years earlier that had failed. There are advantages and disadvantages to both systems - PVC is harder and expands and contracts less, but it's more brittle than ABS and breaks more easily, especially when cold. Plus, it takes both glue and primer and is harder to cut, which adds to installation time.

Assuming you get the right pieces, both are approved, and most areas only stock one; finding the other is hard.

Some areas call for using all ABS inside a house, I was told that when burned PVC gives off chlorine gas. Sounded kind of stupid to me, you would be in trouble in a house fire if either were burning. We can use either, but they don't want them mixed using multipurpose glue. They do make primer for ABS pipe too. You also should sand ABS pipe especially if you don't use the ABS primer and glue. I use a lot of PVC, but I like working with the ABS.

PVC: Polyvinyl chloride
ABS: Acrylonitrile butadiene styrene

I don't think either would be considered eco-friendly, but they do use ABS ground up real fine in some tatoo inks.

It's all garbage in reality

But inexperienced hands usually causes the most problems with the product.

ABS is notorious for cracking longways down the pipe, just like CPVC when it freezes.

Too often people stretch that pipe into position and that's where all the problems start.

Trailers are loaded with this stuff. When I first got out on my own I "thought" it was a market worth tapping. Got smart real quick after the second job under a trailer and that was it.

NEVER assume on a long break in ABS that it's contained to a small area; go ahead and replace from fitting to fitting because there's usually a hairline crack that isn't leaking.......yet.