Feb 12, 2006, 12:51 PM
Post #2 of 9
I think it will be virtually impossible to find a “plumber” in Mexico with the training and education to install a plumbing system to nob standards in a residence in Mexico. As everyone knows, most toilets do not flush reliably in Mexico. That deficiency has nothing to do with undersized piping. It is because the plumbing systems are not vented here. I have never seen a residence in Mexico with vent pipes protruding through the roof. (I always look for them) The vents are necessary for several reasons, including public health and safety.
Sewer gas is always noxious, sometimes toxic, usually flammable, and sometimes inflammable, it is necessary to vent it out of the system. Flammable and inflammable are not synonyms. Flammable indicates a substance that when ignited will burn. Inflammable indicates an unstable substance that may self-ignite. In other words, it can self-ignite and explode. The content of sewer gas is constantly changing, depending on what has been introduced into the sewer system. If you work in the petrochemical industry you damn soon learn what inflammable means.
All domestic toilets work by siphonage, all of them, including commercial toilets equipped with a flushometer valve. This does not refer to marine, RV, or aircraft toilets. There are only two types of domestic toilets, siphon jet, and washdown. Both of them depend on siphonage to work, when a toilet is flushed the waste material in it is actually sucked into the drainage piping system. When a toilet is flushed, a large amount of water is introduced into the soil pipe; we call it a “slug” of water. The slug of water starts the siphon action in the toilet bowl, never lower the water level on a toilet tank, or in the toilet bowl, you are inviting a stoppage to occur if you do.
If the sewerage system is not vented, two things begin to happen. Pressure begins to build in front of the slug of water, and a partial vacuum begins to form behind it. This slows down the water, and breaks the siphon in the toilet bowl. The result is a stoppage in the toilet.
To install a properly vented plumbing system here would require some drastic revisions in construction methods. Most residences here are built using what is often mistakenly referred to as the “post and beam” method. Actually the post and beam method refers to an obsolete type of wood construction. What is usually used here is a series of vertical concrete columns and horizontal bond beams. The bond beams and some of the columns would need to be penetrated by a properly vented plumbing system, weakening them if they were not modified to add extra strength.
I have never seen true drainage pipefittings for sale in any wholesale or retail business here. True drainage fittings are different than water fittings, having an arc, or “sweep” in the direction of flow. In a venting system they are installed “upside down” to conduct the vented gases to the roof outlets and the atmosphere. Using proper drainage fittings greatly reduces the chance of a stoppage occurring.
Plastic pipe is suitable for drainage systems here. When plastic pipe was first used in plumbing systems nob, it was problematic. The problem was twofold. Those pipes conduct noise efficiently. We found that we had to wrap them with fiberglass insulation as a sound deadener for installations on the upper floors of buildings, or the water flowing through them sounded like a huge leak, especially flushing toilets.
Plastic pipe also has a large expansion rate. This was problematic for plastic pipe used in venting systems. The vent pipes would expand 3 or 4 inches during the day, and contract to their original length at night, breaking the waterproof seals on the roof flashings. A new type of waterproof roof flashing had to be designed with a neoprene seal and a counter flashing attached to the pipe.
If you intend to use copper tubing there is some nomenclature you will find useful to know. Copper pipe intended for drainage is referred to as DWV pipe. That stands for Drainage Waste and Vent. Copper drainage fittings are also referred to as DWV fittings. The thickness of DWV pipe is set to a standard, I trashed all my code books when we moved down here, and I’m not going to the trouble of looking it up now.
Cooper pipe for water is also referred to by special nomenclature, which indicates its thickness. It is designated as type M, type L, and type K. Type M is the thinnest, it is Ok to use in housing, although some local codes nob prohibit its use. Type L is medium thickness and is the most commonly used for all purposes. Type K is extra heavy thickness and is usually used in high-pressure systems, but type L is usually adequate for everything.
It is critical that no copper pipes be in contact with any steel or iron after construction is complete. Do not use steel tie wire to hold copper pipe in place while concrete if being poured. To do so would set up a condition for electrolysis to occur. If necessary, use electricians tape or some other non-conducting material to keep copper pipes from being in contact with any steel components of the building structure. Do not ground an electrical system to any plumbing pipes. That used to be a common method; it is illegal in most jurisdictions nob now.
Electrolysis in this instance is an electro chemical reaction when two dissimilar metal are in contact with one another. The electrons from the metal with the highest content of them, in this case the copper tubing, will migrate to the second metal, which will then reject them and send them back to the first metal. Setting up a very weak electrical circuit. It is, in effect a very low powered battery. The copper pipe will not accept the returning electrons; the water in the pipe will wash them away. This slowly erodes the copper and it will begin leaking.
In 48 years of working in the plumbers and pipe fitters union, I have only seen this condition twice, it is very rare for it to occur. Once was in a home that had a well with a very high iron content for its water supply, and once was in a building with many medical office suites. There were many electronic diagnostic machines there; the installers had grounded every one of them to the plumbing system in the building, destroying it. The only repair possible is to replace all the piping and remove the source of electrolysis. It is amazing to see the results of electrolysis contamination. The pipes will be wet from one end to the other. If you wipe them dry with a rag, while you watch, the pipes will slowly become wet again. You will not be able to discern where the leaks are. There will be millions of microscopic holes in the pipe.
Electrolysis is really bad news. Don’t do anything that by the wildest stretch of your imagination could possibly cause it to occur.
For more information I would suggest doing a Google search for “plumbing codes”, you will find a lot of info there, and some good illustrations. I would also recommend looking at some wholesale plumbing supply businesses online too. Some of them have good illustrations of the fittings they sell. Remember, there is specific nomenclature used in the building trades that the average layman will not understand. If you call to order an “elbow” and the salesperson determines that it is for a drainage system, he will know that what you really want is a “Quarter bend.” He will then ask you if you want a short sweep, medium sweep or long sweep quarter bend?
Good luck, you’ve got your work cut out for you, Rex
"The supreme happiness of life is the conviction that we are loved" - Victor Hugo
(This post was edited by RexC on Feb 12, 2006, 12:58 PM)