The Home Medical Library Volume V Part 15

=Connections.=--The connections of the branch sewers and the house sewers with the main sewer must be carefully made, so that there shall be no impediment to the flow of the contents, either of the branches or of the main pipe. The connections must be made gas-tight; not at right angles or by T branches, but by bends, curves, and Y branches, in the direction of the current of the main pipe, and not opposite other branch pipes; and the junction of the branch pipes and the main pipe must not be made at the crown or at the bottom of the sewer, but just within the water line.

=Tide Valves.=--Where sewers discharge their contents into the sea, the tide may exert pressure upon the contents of the sewer and cause "backing up," blocking up the sewer, bursting open trap covers, and overflowing into streets and houses. To prevent this, there are constructed at the mouth of the street sewers, at the outlets to the sea, proper valves or tide flaps, so constructed as to permit the contents of the sewers to flow out, yet prevent sea water from backing up by immediately closing upon the slightest pressure from outside.

=House Sewers.=--Where the ground is "made," or filled in, the house sewer must be made of cast iron, with the joints properly calked with lead. Where the soil consists of a natural bed of loam, sand, or rock, the house sewer may be of hard, salt-glazed, and cylindrical earthenware pipe, laid in a smooth bottom, free from projections of rock, and with the soil well rammed to prevent any settling of the pipe. Each section must be wetted before applying the cement, and the s.p.a.ce between each hub and the small end of the next section must be completely and uniformly filled with the best hydraulic cement. Care must be taken to prevent any cement being forced into the pipe to form an obstruction. No tempered-up cement should be used. A straight edge must be used inside the pipe, and the different sections must be laid in perfect line on the bottom and sides.

Connections of the house sewer (when of iron) with the house main pipe must be made by lead-calked joints; the connection of the iron house pipe with the earthenware house sewer must be made with cement, and should be gas-tight.

=Sewer Air and Gas.=--Sewer gas is not a gas at all. What is commonly understood by the term is the air of sewers, the ordinary atmospheric air, but charged and contaminated with the various products of organic decomposition taking place in sewers. Sewer air is a mixture of gases, the princ.i.p.al gases being carbonic acid; marsh gas; compounds of hydrogen and carbon; carbonate and sulphides of ammonium; ammonia; sulphureted hydrogen; carbonic oxide, volatile fetid matter; organic putrefactive matter, and may also contain some bacteria, saprophytic or pathogenic.

Any and all the above const.i.tuents may be contained in sewer air in larger or smaller doses, in minute or toxic doses.

It is evident that an habitual breathing of air in which even minute doses of toxic substances and gases are floating will in time impair the health of human beings, and that large doses of those substances may be directly toxic and dangerous to health. It is certainly an error to ascribe to sewer air death-dealing properties, but it would be a more serious mistake to undervalue the evil influence of bad sewer air upon health.

=Ventilation.=--To guard against the bad effects of sewer air, it is necessary to dilute, change, and ventilate the air in sewers. This is accomplished by the various openings left in the sewers, the so-called lamp and manholes which ventilate by diluting the sewer air with the street air. In some places, chemical methods of disinfecting the contents of sewers have been undertaken with a view to killing the disease germs and deodorizing the sewage. In the separate system of sewage disposal, where sewer pipes are small and usually self-cleansing, the late Colonel Waring proposed to ventilate the sewers through the house pipes, omitting the usual disconnection of the house sewer from the house pipes. But in the combined system such a procedure would be dangerous, as the sewer air would be apt to enter the house.

Rain storms are the usual means by which a thorough flus.h.i.+ng of the street sewers is effected. There are, however, many devices proposed for flus.h.i.+ng sewers; e. g., by special flus.h.i.+ng tanks, which either automatically or otherwise discharge a large volume of water, thereby flus.h.i.+ng the contents of the street sewers.

CHAPTER VI

=Plumbing=

=Purpose and Requisites for House Plumbing.=--A system of house plumbing presupposes the existence of a street sewer, and a water-supply distribution within the house. While the former is not absolutely essential, as a house may have a system of plumbing without there being a sewer in the street, still in the water-carriage system of disposal of sewage the street sewer is the outlet for the various waste and excrement.i.tious matter of the house. The house-water distribution serves for the purpose of flus.h.i.+ng and cleaning the various pipes in the house plumbing.

The purposes of house plumbing are: (1) to get rid of all excreta and waste water; (2) to prevent any foreign matter and gases in the sewer from entering the house through the pipes; and (3) to dilute the air in the pipes so as to make all deleterious gases therein innocuous.

To accomplish these results, house plumbing demands the following requisites:

(1) _Receptacles_ for collecting the waste and excreta. These receptacles, or plumbing fixtures, must be adequate for the purpose, small, noncorrosive, self-cleansing, well flushed, accessible, and so constructed as to easily dispose of their contents.

(2) _Separate Vertical Pipes_ for sewage proper, for waste water, and for rain water; upright, direct, straight, noncorrosive, water- and gas-tight, well flushed, and ventilated.

(3) Short, direct, clean, well-flushed, gas-tight branch pipes to connect receptacles with vertical pipes.

(4) _Disconnection_ of the house sewer from the house pipes by the main trap on house drain, and disconnection of house from the house pipes by traps on all fixtures.

(5) _Ventilation_ of the whole system by the fresh-air inlet, vent pipes, and the extension of all vertical pipes.

=Definitions.=--The _House Drain_ is the horizontal main pipe receiving all waste water and sewage from the vertical pipes, and conducting them outside of the foundation walls, where it joins the house sewer.

The _Soil Pipe_ is the vertical pipe or pipes receiving sewage matter from the water-closets in the house.

The _Main Waste Pipe_ is the pipe receiving waste water from any fixtures except the water-closets.

_Branch Soil and Waste Pipes_ are the short pipes between the fixtures in the house and the main soil and waste pipes.

_Traps_ are bends in pipes, so constructed as to hold a certain volume of water, called the water seal; this water seal serves as a barrier to prevent air and gases from the sewer from entering the house.

_Vent Pipes_ are the special pipes to which the traps or fixtures are connected by short-branch vent pipes, and serve to ventilate the air in the pipes, and prevent siphonage.

The _Rain Leader_ is the pipe receiving rain and storm water from the roof of the house.

=Materials Used for Plumbing Pipes.=--The materials from which the different pipes used in house plumbing are made differ according to the use of each pipe, its position, size, etc. The following materials are used: cement, vitrified pipe, lead; cast, wrought, and galvanized iron; bra.s.s, steel, nickel, sheet metal, etc.

_Cement and Vitrified Pipes_ are used for the manufacture of street and house sewers. In some places vitrified pipe is used for house drains, but in most cities this is strongly objected to; and in New York City no earthenware pipes are permitted within the house. The objection to earthenware pipes is that they are not strong enough for the purpose, break easily, and cannot be made gas-tight.

_Lead Pipe_ is used for all branch waste pipes and short lengths of water pipes. The advantage of lead pipes is that they can be easily bent and shaped, hence their use for traps and connections. The disadvantage of lead for pipes is the softness of the material, which is easily broken into by nails, gnawed through by rats, etc.

_Bra.s.s, Nickel, Steel_, and other such materials are used in the manufacture of expensive plumbing, but are not commonly employed.

_Sheet Metal_ and _Galvanized Iron_ are used for rain leaders, refrigerator pipes, etc.

_Wrought Iron_ is used in the so-called Durham system of plumbing.

Wrought iron is very strong; the sections of pipe are twenty feet long, the connections are made by screw joints, and a system of house plumbing made of this material is very durable, unyielding, strong, and perfectly gas-tight. The objections to wrought iron for plumbing pipes are that the pipes cannot be readily repaired and that it is too expensive.

_Cast Iron_ is the material universally used for all vertical and horizontal pipes in the house. There are two kinds of cast-iron pipes manufactured for plumbing uses, the "standard and the extra heavy."

The following are the relative weights of each:

Standard. Extra Heavy.

2-inch pipe, 4 lbs. per foot 5-1/2 lbs.

3 " " 6 " " " 9-1/2 "

4 " " 9 " " " 13 "

5 " " 12 " " " 17 "

6 " " 15 " " " 20 "

7 " " 20 " " " 27 "

8 " " 25 " " " 33-1/2 "

The light-weight pipe, though extensively used by plumbers, is generally prohibited by most munic.i.p.alities, as it is not strong enough for the purpose, and it is difficult to make a gas-tight joint with these pipes without breaking them.

Cast-iron pipes are made in lengths of five feet each, with an enlargement on one end of the pipe, called the "hub" or "socket," into which the other, or "spigot," end is fitted. All cast-iron pipe must be straight, sound, cylindrical and smooth, free from sand holes, cracks, and other defects, and of a uniform thickness.

The thickness of cast-iron pipes should be as follows:

2-inch pipe, 5/16 inches thick 3 " " " " "

4 " " 3/8 " "

5 " " 7/16 " "

6 " " 1/2 " "

Cast-iron pipes are sometimes coated by dipping into hot tar, or by some other process. Tar coating is, however, not allowed in New York, because it conceals the sand holes and other flaws in the pipes.

=Joints and Connections.=--To facilitate connections of cast-iron pipes, short and convenient forms and fittings are cast. Some of these connections are named according to their shape, such as L, T, Y, etc.

[Ill.u.s.tration: FIG. 16.