Plumbers should always arrange for soil-pipes to be fixed outside the outer wall of house, and to be carried up full bore to a point above the roof where blow-down of wind cannot occur, and where the outlet will be as far as possible from skylights, chimneys, or windows. Soil-pipes must frequently be fixed at the end of return buildings below the level of main building roof. Any attempt to make outlet shafts in such a position will fail, unless air disconnector and inlet be placed at the foot, for the same reason that a stove flue so placed will discharge the smoke into the house rather than up the flue. When the wind blows towards the house from the back these pipes may sometimes draw, but then the foul air or smoke must be driven in at the back windows. In such a position, if a disconnector cannot be attached, the proper plan will be to utilise the soil-pipe of the return water-closet as a downward fresh-air inlet, and to provide the main upward, outward ventilating shaft from the drain in the front to the top of the main house roof.
Opinions differ as to the best size for soil-pipes. A Glasgow authority recommends five inches in diameter, while a London authority maintains that he has proved that three inches in diameter may be used, even though several water-closets are branched thereto. The mean of these extremes will be about right, for these reasons : 5-inch soil-pipes are not thoroughly cleansed by restricted flushes of water, so that the soil adheres to and dries on the sides, vitiating the internal air. Large soil-pipes are more costly, and, in order to possess equal strength, must be as much heavier as they are larger than 4-inch diameter pipes. They therefore occupy more space, look more clumsy, and are more difficult and costly to fix. Three-inch soil-pipes will really cleanse no better than 3½-inch or 4-inch, because these cleanse perfectly with 3-gallon water flushes, and 3-inch pipes are more liable to hold the descending column of water, together acting as a pump piston, driving the air before it and sucking the air behind, creating a vacuum, and tending to unsyphon the traps of the fittings connected with it. The maintenance of the water-seals of traps is one of the most important duties of a plumber, and should be well considered, so that in some positions, perhaps, 4-inch and even 4½-inch soil-pipes might be safer sizes. Generally, however, 3½-inch and 4-inch will be found sufficient.
<Callout type="important" title="Critical Ventilation">Proper ventilation is crucial to prevent foul air from entering the house through improperly placed or sized soil pipes.</Callout>
Syphonage of traps should always be guarded against by using suitable traps and ventilating the outgo bend of every trap separately and fully. These vent-pipes may be taken direct to the roof level, or be joined into the ventilated soil-pipe above the highest intake branch.
The best material for soil-pipes is undoubtedly drawn-lead piping; it possesses the qualities of smoothness of surface, freedom from corrosion, pliability in bending, security in jointing, and the peculiarity that the material remains valuable even when worn out. The weight of lead in soil-pipes should not be less than that of seven pounds to the square foot, and though eight, nine, and ten pounds would prove better in the long run, such good work is seldom ordered or sanctioned.
<Callout type="risk" title="Lead Joint Risks">Improperly made lead joints can allow foul air into homes, posing serious health risks.</Callout>
Cast iron has also advantages as a material for soil-pipes : it is cheap, which suits the public ; it is easy to fix, which suits the second-rate plumber. Rain-water pipes are used for this purpose, but are very much too light; stove-pipes and underground water-pipes are clumsy and ugly; but special heavy-cast soil-pipes answer the purpose in every possible respect.
Key Takeaways
- Proper placement of soil pipes is essential to prevent foul air from entering homes.
- The ideal size for soil pipes balances cost and effectiveness, typically ranging between 3½-inch and 4-inch diameters.
- Maintaining water seals in traps is crucial to prevent siphoning and ensure proper drainage.
Practical Tips
- Use cast iron or drawn-lead piping for soil pipes due to their durability and resistance to corrosion.
- Ensure that vent-pipes are properly connected to the roof level or above the highest intake branch for effective ventilation.
- Regularly inspect and maintain soil pipe joints to prevent leaks and ensure proper air flow.
Warnings & Risks
- Improper placement of soil pipes can lead to foul air being drawn into homes, causing health issues.
- Neglecting water seal maintenance in traps can result in siphoning, leading to blockages and contamination.
Modern Application
While the specifics of plumbing materials and techniques have evolved since 1903, the principles of proper ventilation and drainage remain crucial for maintaining a healthy living environment. Understanding historical methods provides valuable insights into ensuring effective modern plumbing systems.
Frequently Asked Questions
Q: What are the recommended sizes for soil pipes?
The text suggests that soil-pipes should typically be between 3½-inch and 4-inch in diameter, balancing cost and effectiveness.
Q: Why is proper ventilation important for soil pipes?
Proper ventilation prevents foul air from entering the house through improperly placed or sized soil pipes, ensuring a healthy living environment.
Q: What are the benefits of using drawn-lead piping over other materials?
Drawn-lead piping is praised for its smoothness, resistance to corrosion, pliability in bending, and secure jointing, making it ideal for soil pipes despite being more expensive.