HOUSE TRAPS, FRESH-AIR CONNECTIONS, DRUM TRAPS, AND NON-SYPHONING
TRAPS
The _house trap_ is a deep seal trap placed inside the foundation
wall, and intersects the house drain and house sewer. The trap is
placed at this point for a number of reasons: first, to keep sewer
gases from entering the pipes in the house; second, this location
is where the house drain ends. This trap should have two
clean-outs, one on each side of the seal. The clean-outs should be
of extra heavy cast-iron body with a heavy brass screw cap. The cap
should have a square nut for a wrench to tighten or unscrew the
cap. This cap should be brought up flush with the floor. When a
house trap is being set, it is necessary to set it perfectly level,
otherwise the seal of the trap is weakened and sewer gases can
enter.
Sometimes the trap is located on the house sewer just outside of
the foundation wall. In this case, a pit should be built large
enough for a workman to get down to it to clean it out when
necessary.
_A mason's trap_ was formerly used to a considerable extent, but is
very poor practice to use today on modern work. This trap was built
square of brick with a center partition. The brick soon became foul
and the trap would be better termed a small cesspool than a trap.
POINTS TO REMEMBER ABOUT HOUSE TRAPS.--
_First_, should be a running trap.
_Second_, two clean-outs.
_Third_, deep seal, at least 2 inches.
_Fourth_, set level.
_Fifth_, set inside foundation wall.
_Sixth_, accessible at all times.
_Seventh_, same size as house drain.
_Eighth_, fresh air should connect with it.
FRESH-AIR CONNECTIONS
The term "fresh-air inlet" is, as its name implies, an inlet for
fresh air. It is placed directly on the house side of the main
trap. The connections made vary considerably. A few good
connections in common use are explained below.
When the trap is in place, one of the clean-outs can be used for
the fresh air. If this is done, a Y-branch should be placed in the
hub of the clean-out. The Y-branch should be used for the fresh air
and the run should be used for a clean-out.
A Y-fitting can be inserted directly back of the trap and the
branch used for the fresh air. An inverted Y makes a good fitting
to use directly back of the trap. These branches should be taken
off the top of the pipe. The branch taken off for the fresh-air
inlet should not have any waste discharge into it and should not be
used for a drain pipe of any description.
The fresh-air inlet should run as directly as possible into the
outer air, at least 15 feet from any window. The pipes terminate in
a number of different ways, some with a return bend, above the
ground, some with a cowl cap, some with a strainer. When necessary
to run pipe through the sidewalk, a box of brick is made with a
heavy brass strainer fitted level with the sidewalk into which the
pipe runs. If the pipe is run into the box on the side a little up
from the bottom, the possibility of becoming stopped up or filled
up is not great. The fresh-air inlet sometimes terminates above the
roof of the building.
Special care should be given this fresh-air inlet as it supplies
fresh air to the entire system and thus keeps the pipes in a much
better sanitary condition.
Sometimes when the house drain is full of sewage, air is pushed out
of the fresh-air inlet and disagreeable odors are evident. This is
why it should be located as far as possible from any window.
Special care should be taken on the part of the plumber not to
locate the fresh-air inlet nearer than 15 feet to the fresh-air
intake of the heating system.
[Illustration: FIG. 60.--Fresh-air inlet.]
When the pipe passes through the foundation wall, the same care
should be exercised as with other pipes. That is, if the pipe is 4
inches, a sleeve 6 inches should be cut in the wall for the 4-inch
pipe to pass through.
POINTS TO REMEMBER ABOUT FRESH AIR.--
_First_, never should be smaller than 4 inches.
_Second_, one size smaller than trap.
_Third_, location, directly back of trap.
_Fourth_, leads to outer air.
_Fifth_, keep away from windows and intake of heating system.
_Sixth_, always have end of pipe covered with strainer, cowl, or
return bend.
_Seventh_, make as few bends as possible.
_Eighth_, supplies fresh air to system.
DRUM TRAP
The use of the drum trap is very handy to the plumber as well as
efficient and practicable when installed. The trap can be purchased
without any outlets or inlets, so the plumber can put them in
according to the necessary measurements. The making of these traps
with lead is explained in the chapter on Wiping Joints. The open
end has a brass clean-out screw on it. When this clean-out screw
comes below the floor, another brass screw cap and flange is
screwed on the floor above the trap so that the clean-out screw in
the trap is easily accessible.
[Illustration: FIG. 61.--Drum trap.]
These drum traps are called bath traps as they are used mostly on
bath wastes. They should never be installed with the clean-out
exposed to the sewer side of the trap. In the best practice, heavy
brass drum traps are used.
NON-SYPHONING TRAP
[Illustration: FIG. 62.--Flask trap.]
[Illustration: FIG. 63.--Clean-sweep trap.]
After years of experimenting to produce a trap that would not
syphon without venting, we find in use today a large variety of
non-syphoning traps. Traps that will hold their seal against all
practical forms of syphonic action, or other threatening features,
have been made and used and serve the purpose for which they are
intended. Various means to prevent the breaking of the seal of
these traps are employed. While some depend on a ball or other kind
of valve, others rely on partitions and deflections of various
kinds. All of these perform the functions for which they are
designed, yet the devices employed offer an excellent obstruction
for the free passage of waste; therefore, in time, these traps
become inoperative. It should be borne in mind that any traps with
a mechanical seal or an inside partition are not considered
sanitary. The inside partition might wear out or be destroyed and
thus break the seal without the knowledge of anyone and allow sewer
gas to enter the room. The mechanical device may also be displaced
or destroyed, leaving the trap without a seal. If the trap were
cleaned out often or examined occasionally, these traps could be
used with a greater degree of safety. Some of the forms of
non-syphon traps in common use are:
The _Flask Trap_, Fig. 62. This trap gets its name from its
shape. There is an inside wall upon which the seal depends.
This trap is like the bag trap, only the two inside walls of
the pipe are combined into one. This wall should be of heavy
cast brass, free from sand holes.
_Clean Sweep Trap_, Fig. 63. Some clean sweep traps are
dependent upon an inside wall for their seals. They are made
of 1/2-S, 3/4-S, and full S.
[Illustration: FIG. 64.--Mechanical-seal trap.]
[Illustration: FIG. 65.--Standard "S" trap.]
[Illustration: FIG. 66.--Bag trap.]
_Sure Seal Trap._ The sure seal trap is designed to be
non-syphoning. This trap also has an interior waterway. If
this waterway leaks, the trap is unfit for use. If these traps
are made as shown in the second sketch with the way inside of
a larger pipe, it can be detected if the interior wall leaks.
_Centrifugal Trap._ The centrifugal trap is made similar to
the clean sweep, except that the wall of the inlet pipe is
entirely separate from the body of the trap. The inlet enters
the body of the trap on a tangent, thus making the trap
self-scouring which is a good feature.