=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 excrementitious matter of the house. The house-water
distribution serves for the purpose of flushing 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; brass, 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.
_Brass, 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 municipalities, 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.
[Illustration: FIG. 16.
DIFFERENT FORMS AND FITTINGS.]
_Iron Pipe_ is joined to _Iron Pipe_ by lead-calked joints. These
joints are made as follows: the spigot end of one pipe is inserted
into the enlarged end, or the "hub," of the next pipe. The space
between the spigot and hub is half filled with oakum or dry hemp. The
remaining space is filled with hot molten lead, which, on cooling, is
well rammed and calked in by special tools made for the purpose. To
make a good, gas-tight, lead-calked joint, experience and skill are
necessary. The ring of lead joining the two lengths of pipe must be
from 1 to 2 inches deep, and from 1/2 to 3/4 of an inch thick; 12
ounces of lead must be used at each joint for each inch in the
diameter of the pipe. Iron pipes are sometimes connected by means of
so-called rust joints. Instead of lead, the space between the socket
and spigot is filled in with an iron cement consisting of 98 parts of
cast-iron borings, 1 part of flowers of sulphur, and 1 part of sal
ammoniac.
[Illustration: FIG. 17.]
All connections between _Lead Pipes_ and between _Lead_ and _Brass_ or
_Copper_ pipes must be made by means of "wiped" solder joints. A wiped
joint is made by solder being poured on two ends of the two pipes, the
solder being worked about the joint, shaped into an oval lump, and
wiped around with a cloth, giving the joint a bulbous form.
All connections between _Lead Pipes_ and _Iron Pipes_ are made by
means of brass ferrules. Lead cannot be soldered to iron, so a brass
fitting or ferrule is used; it is jointed to the lead pipe by a wiped
joint, and to the iron pipe by an ordinary lead-calked joint.
_Putty_, _Cement_, and _Slip_ joints should not be tolerated on any
pipes.
[Illustration: FIG. 18.]
=Traps.=--We have seen that a trap is a bend in a pipe so constructed
as to hold a quantity of water sufficient to interpose a barrier
between the sewer and the fixture. There are many and various kinds of
traps, some depending on water alone as their "seal," others employing
mechanical means, such as balls, valves, lips, also mercury, etc., to
assist in the disconnection between the house and sewer ends of the
pipe system.
The value of a trap depends: (1) on the depth of its water seal; (2)
on the strengths and permanency of the seal; (3) on the diameter and
uniformity of the trap; (4) on its simplicity; (5) on its
accessibility; and (6) on its self-cleansing character.
The depth of a trap should be about three inches for water-closet
traps, and about two inches for sink and other traps.
Traps must not be larger in diameter than the pipe to which they are
attached.
The simpler the trap, the better it is.
Traps should be provided with cleanout screw openings, caps, etc., to
facilitate cleaning.
The shapes of traps vary, and the number of the various kinds of traps
manufactured is very great.
Traps are named according to their use: gully, grease, sediment,
intercepting, etc.; according to their shape: D, P, S, V, bell,
bottle, pot, globe, etc.; and according to the name of their
inventor: Buchan, Cottam, Dodd, Antill, Renk, Hellyer, Croydon, and
others too numerous to mention.
The S trap is the best for sink waste pipes; the running trap is the
best on house drains.
[Illustration: FIG. 19.
FORMS OF TRAPS.]
[Illustration: FIG. 20.
FORMS OF TRAPS.]
=Loss of Seal by Traps.=--The seals of traps are not always secure,
and the causes of unsealing of traps are as follows:
(1) _Evaporation._--If a fixture in a house is not used for a long
time, the water constituting the seal in the trap of the fixture will
evaporate; the seal will thus be lost, and ingress of sewer air will
result. To guard against evaporation, fixtures must be frequently
flushed; and during summer, or at such times as the house is
unoccupied and the fixtures not used, the traps are to be filled with
oil or glycerin, either of which will serve as an efficient seal.
(2) _Momentum._--A sudden flow of water from the fixture may, by the
force of its momentum, empty all water in the trap and thus leave it
unsealed. To prevent the unsealing of traps by momentum, they must be
of a proper size, not less than the waste pipe of the fixture, the
seal must be deep, and the trap in a perfectly straight position, as a
slight inclination will favor its emptying. Care should also be taken
while emptying the fixture to do it slowly so as to preserve the seal.
(3) _Capillary Attraction._--If a piece of paper, cotton, thread,
hair, etc., remain in the trap, and a part of the paper, etc.,
projects into the lumen of the pipe, a part of the water will be
withdrawn by capillary attraction from the trap and may unseal it. To
guard against unsealing of traps by capillary attraction, traps should
be of a uniform diameter, without nooks and corners, and of not too
large a size, and should also be well flushed, so that nothing but
water remains in the trap.
_Siphonage and Back Pressure._--The water in the trap, or the "seal,"
is suspended between two columns of air, that from the fixture to the
seal, and from the seal of the trap to the seal of the main trap on
house drain. The seal in the trap is therefore not very secure, as it
is influenced by any and all currents and agitations of air from both
sides, and especially from its distal side. Any heating of the air in
the pipes with which the trap is connected, any increase of
temperature in the air contents of the vertical pipes with which the
trap is connected, and any evolution of gases within those pipes will
naturally increase the weight and pressure of the air within them,
with the result that the increased pressure will influence the
contents of the trap, or the "seal," and may dislodge the seal
backward, if the pressure is very great, or, at any rate, may force
the foul air from the pipes through the seal of the traps and foul the
water therein, thus allowing foul odors to enter the rooms from the
traps of the fixtures. This condition, which in practice exists
oftener than it is ordinarily thought, is called "back pressure." By
"back pressure" is therefore understood the _forcing back_, or, at
least, the _fouling_, of the water in traps, due to the increased
pressure of the air within the pipes back of the traps; the increase
in air pressure being due to heating of pipes by the hot water
occasionally circulating within them, or by the evolution of gases due
to the decomposition of organic matter within the pipes.
[Illustration: FIG. 21.
NON-SYPHONING TRAP.
Copyright by the J. L. Mott Iron Works.]
A condition somewhat similar, but acting in a reverse way, is
presented in what is commonly termed "siphonage." Just as well as the
seal in traps may be forced back by the increased pressure of the air
within the pipes, the same seal may be _forced out_, pulled out,
aspirated, or siphoned out by a sudden withdrawal of a large quantity
of air from the pipes with which the trap is connected. Such a sudden
withdrawal of large quantities of air is occasioned every time there
is a rush of large column of water through the pipes, e. g., when a
water-closet or similar fixture is suddenly discharged; the water
rushes through the pipes with a great velocity and creates a strong
down current of air, with the result that where the down-rushing
column passes by a trap, the air in the trap and, later, its seal are
aspirated or siphoned out, thus leaving the trap without a seal. By
"siphonage" is therefore meant the emptying of the seal in a trap by
the aspiration of the water in the trap due to the downward rush of
water and air in the pipes with which the trap is connected.
To guard against the loss of seal through siphonage "nonsiphoning"
traps have been invented, that is, the traps are so constructed that
the seal therein is very large, and the shape of the traps made so
that siphonage is difficult. These traps are, however, open to the
objection that in the first place they do not prevent the fouling of
the seals by back pressure, and in the second place they are not
easily cleansable and may retain dirt in their large pockets. The
universal method of preventing both siphonage and back pressure is by
the system of vent pipes, or what plumbers call "back-air" pipes.
Every trap is connected by branches leading from the crown or near the
crown of the trap to a main vertical pipe which runs through the house
the same as the waste and soil pipes, and which contains nothing but
air, which air serves as a medium to be pressed upon by the
"back-pressure" air, or to be drawn upon by the siphoning, and thus
preventing any agitation and influence upon the seal in the traps; for
it is self evident that as long as there is plenty of air at the
distal part of the seal, the seal itself will remain uninfluenced by
any agitation or condition of the air within the pipes with which the
trap is connected.
The vent-pipe system is also an additional means of ventilating the
plumbing system of the house, already partly ventilated by the
extension of the vertical pipes above the roof and by the fresh-air
inlet. The principal objection urged against the installation of the
vent-pipe system is the added expense, which is considerable; and
plumbers have sought therefore to substitute for the vent pipes
various mechanical traps, also nonsiphoning traps. The vent pipes are,
however, worth the additional expense, as they are certainly the best
means to prevent siphonage and back pressure, and are free from the
objections against the cumbersome mechanical traps and the filthy
nonsiphoning traps.