Today I purchased a digital level that can produce an audible tone when level or matching a programmed slope. I found it convenient enough to simply read the digital screen for the slope. The display can be configured to read in degrees, inches/ft, or percentage. I also procured some velcro tape from my mom, and used that to affix the level to the pipe. Then I was free to adjust the height of the pipe until just right, and nail the hanger in place.
Hanging pipe
I'm using plastic strapping, also known as plastic plumber's tape. It's a perforated strapping with holes for driving nails or screws through. I found that the pipes don't fully stretch out the strapping loop, and so they will move down some if you press down on the pipe. I've been attaching the strapping in a "U" shape, with the pipe resting in the center - perhaps changing that to a "d" shape would keep the vertical portion taught? Then again, as the pipework is welded together, it acquires a preferred position which tends not to align with where it needs to go, and I suppose this contributes to the lack of stretched strapping. I plan to supplement the straps with a few well-placed 2x4s braced against the pipe to direct it into proper position.
Pipe orientation
After cutting a section of pipe, I lay it on a nice and flat area of the floor. Two hubbed fittings are temporarily attached to the ends, which helps keep the pipe from rotating. I took a scrap block and placed a pen on top, with its point protruding from the block's edge. Then i slide the block/pen along the pipe at each end, on the same side, creating a longitudinal reference line at the same angle on both ends.
Then I pop off the fittings and bring the pipe to the pipework being assembled. The existing hub and the pipe end are primed and cemented. Then, when inserting them together, I am sure to align the pen mark with a reference mark on the fitting. Some fittings have reference ticks on the hubs at every 45 degrees. Others only have two lines where the piece was welded together during manufacture I think. In either case, the lines are at specific orientations of the fitting - pointing straight down, up, left, right.. Using these lines & the lines on the pipe when connecting fittings, I am assured the fittings are aligned exactly as they should be relative to each other. Sometimes I have to add a reference mark on a hub that only has weld lines - this is easy, just place it against a hub with reference marks.
Play
I have found the pipework once glued together has quite a bit of play in that it can be moved quite a ways from where it wants to sit. I know any undue stress is more likely to cause a leak, so we'll see eventually when I test the system if I was too rough with any sections. For now I'm just moving along.
Sunday, November 28, 2010
dwv plumbing
Yesterday, I started gluing together PVC pipes for the DWV system. This is the first time doing this, so things are moving slowly as I determine how best to do things and develop methods.
Attaching a pipe
From what I gather, typically some portion of the system is fixed into place with strapping or whatever it takes. Let's say a fitting is in place. Then the connecting pipe has one end placed into the fixed fitting, and the other end will be placed at the proper elevation such that the pipe is at a proper slope. This involves:
A. Supporting the pipe
B. Checking the slope of the pipe
These must be performed at the same time. For example:
1. Temporarily hang the pipe roughly where it should be
2. Check the slope
3. Adjust the hanger
4. Check again - if it's good enough, the support is correct
5. Go to step 3
This process is repeated as each pipe is attached, so we want to optimize it. That is, check the slope quickly, and adjust the hanger quickly.
Yesterday, I was running a tape measure vertically from the bottom of the pipe, and reading where my horizontal laser level crossed the tape. This would give a level reading from the reference laser. Given the length of the pipe, I can calculate how much the elevation should change, add/subtract that amount, and adjust the other end of the pipe until it meets that reading.
It's fast putting up the tape and reading the elevation. But it's slow to calculate the change in elevation to meet slope, it's confusing determining whether to add or subtract. It sounds simple, but seriously that was slow and confusing.
Today I'm going to try taking my bubble levels and taping on shims for the proper slope so when placed against the pipe it reads level. This is equivalent to using a plumber's level and I think this is how it's typically done. So now checking the level is simply placing the level against the bottom of the pipe and checking the bubble. This is a little slower than just reading elevation from the tape, but it's faster in that I don't have to calculate stuff. If I had a level that produced noise when it was level, I could strap it to the pipe say with velcro, and adjust it by hand just once.. I'll have to look into this.
Attaching a fitting
Attaching fittings is different from pipe, in that their relative orientation is important. For example, take a 90-degree bend. With one end attached to the pipe, the other end can swing around to point in any direction perpendicular to the slope of the pipe. Of course, it has a specific direction in which we want it to point, but the problem is getting it oriented precisely where it should go. Once it's glued, it's not moving.
This is a more difficult problem, and I'm still in the process of determining how to do this best. I believe this is achieved by working your way from fixed points (like where you drop from above at a lavatory/water closet drain) and hanging pipe to the junction, cut to proper length with accurate premeasurement & calculation. With these pipes glued into place and hanging where they should go, the fitting can be glued into place and will naturally be oriented in only one way. The difficulty with this idea is that the pipes all have play in them, so they need to be affixed to proper orientation as well as possible before doing this (that is, prevent the pipe & its attached fittings from rotating about the pipe's longitudinal axis.)
In my design, and I'd imagine most designs, the fittings all connect at standard orientations. That is, either in-line or at 45 or 90 degree angles to previous fittings. Unfortunately, the pipes between the fittings have no longitudinal reference lines, so you can't simply align two reference marks on the fittings to ensure they are at exact relative angles. The lack of these reference lines on the pipes seems like the most bone-headed missing feature of a manufactured product I've come across in construction so far. Unless these pipes tend to somewhat twist along their longitudinal axis after manufacture, then I see no reason why they don't paint/print one or more lines down the pipe for plumbers to use as a reference line.. That would be immensely useful. I'm considering securing the pipe on a flat surface and making my own reference marks at ends of the cut sections of pipe to orient fittings when gluing..
It would be easiest to just dry-fit everything into place, draw reference marks between pieces, then take it apart, glue together, and rejoin. In fact, many online references say to do this. Which is stupid. You can't dry-fit pieces of PVC together, they don't fully seat until you prime & glue them. That technique might work with other types of pipe that you can fully seat before welding together. And it could work with PVC if you only had a simple configuration with large tolerances.
This could be explained better with step-by-step pictures, but I'm trying to figure this out, and trying to get work done, not trying to teach you stuff! OK I'm going to go try this all out now..
Hopefully it will warm up!
Attaching a pipe
From what I gather, typically some portion of the system is fixed into place with strapping or whatever it takes. Let's say a fitting is in place. Then the connecting pipe has one end placed into the fixed fitting, and the other end will be placed at the proper elevation such that the pipe is at a proper slope. This involves:
A. Supporting the pipe
B. Checking the slope of the pipe
These must be performed at the same time. For example:
1. Temporarily hang the pipe roughly where it should be
2. Check the slope
3. Adjust the hanger
4. Check again - if it's good enough, the support is correct
5. Go to step 3
This process is repeated as each pipe is attached, so we want to optimize it. That is, check the slope quickly, and adjust the hanger quickly.
Yesterday, I was running a tape measure vertically from the bottom of the pipe, and reading where my horizontal laser level crossed the tape. This would give a level reading from the reference laser. Given the length of the pipe, I can calculate how much the elevation should change, add/subtract that amount, and adjust the other end of the pipe until it meets that reading.
It's fast putting up the tape and reading the elevation. But it's slow to calculate the change in elevation to meet slope, it's confusing determining whether to add or subtract. It sounds simple, but seriously that was slow and confusing.
Today I'm going to try taking my bubble levels and taping on shims for the proper slope so when placed against the pipe it reads level. This is equivalent to using a plumber's level and I think this is how it's typically done. So now checking the level is simply placing the level against the bottom of the pipe and checking the bubble. This is a little slower than just reading elevation from the tape, but it's faster in that I don't have to calculate stuff. If I had a level that produced noise when it was level, I could strap it to the pipe say with velcro, and adjust it by hand just once.. I'll have to look into this.
Attaching a fitting
Attaching fittings is different from pipe, in that their relative orientation is important. For example, take a 90-degree bend. With one end attached to the pipe, the other end can swing around to point in any direction perpendicular to the slope of the pipe. Of course, it has a specific direction in which we want it to point, but the problem is getting it oriented precisely where it should go. Once it's glued, it's not moving.
This is a more difficult problem, and I'm still in the process of determining how to do this best. I believe this is achieved by working your way from fixed points (like where you drop from above at a lavatory/water closet drain) and hanging pipe to the junction, cut to proper length with accurate premeasurement & calculation. With these pipes glued into place and hanging where they should go, the fitting can be glued into place and will naturally be oriented in only one way. The difficulty with this idea is that the pipes all have play in them, so they need to be affixed to proper orientation as well as possible before doing this (that is, prevent the pipe & its attached fittings from rotating about the pipe's longitudinal axis.)
In my design, and I'd imagine most designs, the fittings all connect at standard orientations. That is, either in-line or at 45 or 90 degree angles to previous fittings. Unfortunately, the pipes between the fittings have no longitudinal reference lines, so you can't simply align two reference marks on the fittings to ensure they are at exact relative angles. The lack of these reference lines on the pipes seems like the most bone-headed missing feature of a manufactured product I've come across in construction so far. Unless these pipes tend to somewhat twist along their longitudinal axis after manufacture, then I see no reason why they don't paint/print one or more lines down the pipe for plumbers to use as a reference line.. That would be immensely useful. I'm considering securing the pipe on a flat surface and making my own reference marks at ends of the cut sections of pipe to orient fittings when gluing..
It would be easiest to just dry-fit everything into place, draw reference marks between pieces, then take it apart, glue together, and rejoin. In fact, many online references say to do this. Which is stupid. You can't dry-fit pieces of PVC together, they don't fully seat until you prime & glue them. That technique might work with other types of pipe that you can fully seat before welding together. And it could work with PVC if you only had a simple configuration with large tolerances.
This could be explained better with step-by-step pictures, but I'm trying to figure this out, and trying to get work done, not trying to teach you stuff! OK I'm going to go try this all out now..
Hopefully it will warm up!
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