ARE 5.0 Project Planning & Design Exam Prep

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Waste and Vent

8m 53s

In this ARE 5.0 NCARB-approved Project Planning and Design Exam Prep course you will learn about the topics covered in the ARE 5.0 PPD exam division. A complete and comprehensive curriculum, this course will touch on each of the NCARB objectives for the ARE 5.0 Project Planning and Design Exam.

Instructor Mike Newman will discuss issues related to the generation or evaluation of design alternatives that synthesize environmental, cultural, behavioral, technical and economic issues.

When you are done with this course, you will have a thorough understanding of the content covered in the ARE 5.0 Project Planning and Design Exam including design concepts, sustainability/environmental design, universal design, and other forms of governing codes and regulations. 

So when we're talking about plumbing, we start thinking about the supply and we have its own riser diagram for that. But then we're also going to have a riser diagram that shows the waste and the vent. We put the waste and the vent together into the same set of drawings. And generally we separate those from the supply drawings. You can do them all as one diagram, but in sort of typical situations it's actually easier to read them if they become separated. Sometimes they're easier if you have a small enough building and sort of a simple enough situation, it's actually easier to put them together.

So you can really tell what parts go to which. But typically it just gets a little confusing if you do that. So generally, separating them is gonna be the way to go. But different firms will do it in different ways, and I don't think that really matters for the exam. But you have the waste and the vent grouped together. Before we get into the riser diagram aspect of it though, just a quick review, we'll remind kind of what's going on. So if we start to imagine that we've got like our sink here, let's say.

So here's our sink. There's our faucet, and we have a little drain pipe down below that. And that drain pipe goes back into the wall. Here's our wall. And then it goes down eventually to the sewer. So okay, that's great. We use water coming out of the faucet, we fill up that sink. Eventually we're done with whatever we're doing here.

And that water is going to sort of find its way down through the system, and it's gonna drain on out. Alright, that's great, so far so good. But remember, the supply pipes are filled with water all the time, and they're under pressure. But the waste pipes are actually empty most of the time. And so once that water in that sink has drained its way through, that's now an empty pipe. And so when you start to realize that's an empty pipe, you realize well eventually this pipe gets down to the street level, to underneath the street, and it goes out and there's a big sewer main that this thing is connecting to.

And that would mean that my nose here, as I'm leaning over and brushing my teeth or whatever it is I'm doing here at the sink. My nose is gonna be smelling directly through that pipe all the way down to that sewer line.

That doesn't sound so good. I'm gonna have this direct connection to the sewer. So that's clearly a problem. So what did they do? Well, very cleverly somebody somewhere along the way, said this isn't any good. So we have our sink. Got our drain. Here's our faucet. And instead of that just going straight down, we have the trap.

So our trap actually traps water. That's a very common question to get on the exam. What does a trap, trap? So the fact that the water as it rushes down and by will leave a little bit of water in the trap, it then stops the smell from being able to get through. The sewer gases can't get through that process, and so we just by this very elegant move of just bending the pipe, we've actually made it so that we can actually stand being inside this building.

If you imagine how quickly it would fill up with that sewer gas smell if you didn't have that trap there, it would be a really unpleasant situation. It doesn't really matter if you were outside, like if this was an open air setup, and air is just blowing through.

Well, the world is a big place, we're not really gonna be bothered by some sewer gases. But if you're in an eight by eight room, that's just constantly filling with sewer gas, clearly that would be just really unpleasant to the point that you just couldn't stand it. You just wouldn't be in that space. So the trap makes this believable. Well, if you had a whole series of these in a row, and I had the next floor going up, and imagine that I have not only sinks but toilets on here, and maybe I've got a whole series of these different fixtures and they're all attached to this same pipe going down to the sewer in the street, and let's say somebody upstairs is washing dishes and dumps a lot of water into their setup.

So they fill this with water, and all of that water comes rushing down this pipe.

And it goes shooting on by. It fills the pipe up and it goes racing by. Well as it goes racing by, it wants to fill in the space behind it, like it's pushing the air out of the way as it goes down into this pipe. But then once the air has been pushed out of the way, something has to replace that air because the water has pushed it out of the way. And so it's gonna be pulling air from wherever it can come from. Well where is it gonna come from?

That air is most likely gonna come from your bathroom. And it's gonna pull that air through and in the process of pulling that air through, that's gonna push all of that water that's in the trap out of the way. So that water in the trap gets suctioned right by once I have this big load of water coming down this pipe. So I have a huge amount of water go by, it creates this vacuum behind it. That's gonna pull the trap water from these other sinks and toilets and everything else through, into the system and therefore once it's gone by, now we're back to the same situation where the trap is open.

Therefore I have a direct line between the sink and the sewer. And so the sewer gases are gonna come up and it's gonna fill the room. So what do you do? Like how do you stop that from happening? Well the way that people figured out how to deal with this, is they essentially put these little vent pipes here. And they took those vent pipes up to the roof.

So I get up to the roof, and there's just a little spot up at the roof where as that rush of water goes by, that air can come in and fill in behind. So the vent pipe is there to sort of balance out the system so that you're not suctioning out all the water in those traps.

The water is in the traps in order to make it plausible to live here. To make it plausible to sort of be in these spaces. So if you didn't have the trap, it would be very difficult to be there. If you do have the trap, you want to keep the water in the trap. And that's what the vent is for. So the vent allows for this air to come fill it in. As that water goes by, it's gonna suction air from somewhere. And it could do it where it's gonna pull the water out of the trap, and get the air from one of these spaces.

But that's much harder to do than just reach up to the roof and pull some other fresh air in. So it's just a simpler way for the pipes themselves to fill air back in behind a rush of water that's going through as you're flushing a toilet. Or as you're emptying a bin where you've been washing dishes or whatever it happens to be. Or letting a tub empty. As that rush of water goes through, it's gonna wanna pull that air behind it, so you're giving it a way to do that.

So that concept, first we have the trap, and then we use the vent to make sure the trap doesn't get compromised. One of the things that people often assume, is that the trap is there in order to trap like wedding rings or something. If you lose one down, and that does actually happen fairly regularly. You can open it up and find stuff there. But that's not what the trap is for. The trap is there to trap water, which traps sewer gas. And the vent is there to balance out the system so that that trap doesn't get emptied accidentally.

So waste and vent working together in order to make this system work in a way that is beneficial. So that you don't just get completely overloaded by all that sewer gas.

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From the course:
ARE 5.0 Project Planning & Design Exam Prep

Duration: 30h 26m

Author: Mike Newman