--Waste From High Rise Buildings--

[peter-pan]

Hi There,
I often wondered about waste and water falling great heights in a Stack installed in a High Rise Building. Is there any precautions taken to stop the acceleration of this mass of water and waste falling from top to bottom??

Is there any damaged caused (perhaps in plastic pipes) from this falling mass?
Regards p-p

[FloridaOrange]

Most high-rises these days are designed as a sol-vent system. Basically the waste swirls around the pipe on the way down. It creates a column of air (vent) up the middle. It gets more complicated then that but here you go for a quick answer.

[hj]

I am not sure if Sovent is the common installation method, or not. I only know of one system in this area and it is many years old. Regular systems have periodic offsets in the riser to slow the velocity.

[FloridaOrange]

I should have said common to this area - S. Florida. I haven't done a sol-vent system in years though, most of my projects top out at 4 stories.

[dubldare]

Contrary to popular belief, water flows in vertical stacks predominately follow the interior of the stack. I've also read that waste will reach it's maximum velocity after falling only 2 stories.

In high rise buildings, fixtures on floors where a vertical stack (which receives waste from fixtures 4 or more stories above) offsets to a horizontal are protected by where those fixtures can connect to the stack (or ultimately, the building drain in case of a lowest floor). Horizontal offsets of stacks are sized as if they were the building drain. Fixtures on the floor where the offset occurs must connect at least 8 feet downstream of the vertical to horizontal offset, or at least 2 feet below the horizontal to vertical offset. This is done to protect those fixtures from back pressure conditions.

Additionally, all 'high rise' buildings (that do not have sovent systems) have a separate vent stack which begins at the base of the soil/waste stack and vents all fixtures connected. The soil/waste stack and vent stack are interconnected at every five stories with a yoke vent, which equalizes pressure between the two stacks.

One generally will not see much if any plastic piping, most notably stacks, in high rise buildings. This is due to expansion and contraction of plastic piping. Even more rare are sovent systems, at least in my neck of the woods.

[hj]

The water is a vertical pipe will gravitate to the perimeter of the pipe because of the air being aspirated by the water's velocity. That is the principle behind the "Philadelphia one stack" design which was just approved by the UPC. The friction against the pipe is what will limit its terminal velocity, although I believe that it will not reach that until more than two floors have been passed.

[TonyBagadonutz]

"Philadelphia one stack" design ....

Interesting....here's a quick article Hotel/Motel Plumbing Utilizing The Philadelphia Single Stack System

This was pretty much the only reference I was able to find.

[dubldare]

Another interseting tidbit is:

http://www.pmengineer.com/CDA/Articl...135186,00.html


I must let it be known that my above post, and probably the vast majority of my postings, refer to the Minnesota Plumbing Code. The MN **** Code could be considered a (rather restrictive) cousin of the UPC, such key differences are not only based on environmental conditions to MN, but also progressive theories of health sanitarians dating as far back as the 1870's. (Statewide licensing of plumbers began in 1933, many municipalities had ordinances regarding licensing and code predating the 1870's.)

I've heard of only one SoVent system allowed in MN, dating back to the 1970's.

I have been transitioning into becoming more knowlegable on the UPC, which is the code in ND. MN **** code allows more of an 'engineered system' style code in relation to venting, whereas the UPC is rather restrictive in vent loading. Commercial kitchens and potable water protection are where MN is much more stringent.

Another key difference is that MN requires a manometer air test at final inspection. Plug the main cleanout, cap the vent terminals. The DWV system must withstand 1" WC (water column) pressure with all fixtures connected, the test time-limit is for the duration of the final inspection. Plan reviews for all plumbing in buildings of public use (gas stations up to hospitals) are required prior to commencement of work.

I appreciate reading about alternate methods allowed by other codes.

As we all know, there are alot of ways to 'skin a cat'.

[hj]

Sovent and the Philadelphia One Stack System, are both "engineered" vent systems. You cannot just decide to use then and then start installing pipe. Either one needs an engineer's seal to verify that they have been designed properly, and must be installed exactly as drawn.