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.
CHAPTER XII
PIPE THREADING
The proper cutting of threads on pipe is overlooked by some mechanics. There are many different kinds of dies and different kinds of pipe to contend with. Steel pipe threads very hard and the adjustable dies should be used on it. These dies cut more easily and leave a cleaner thread than other dies when used on steel pipe.
When threads are cut on wrought-iron pipe the adjustable dies should be used as they cut a better and cleaner thread than other dies. To preserve the life of the dies and the quality of the thread, oil is used freely while the dies are cutting.
THREADS.--The standard thread on pipe and fittings is a right-handed thread. Left threads can be cut on the pipe and the fitting can be tapped with a left thread. When a fitting is tapped with a left thread it is marked so. The following table gives the standard number of threads that a die will or should be allowed to cut on the pipe:
--------+----------------+-------------------+---------------- Size Length, inches Threads per inch Threads per end --------+----------------+-------------------+---------------- 3/8 9/16 18 10.825 1/2 3/4 14 10.500 3/4 3/4 14 10.500 1 15/16 11-1/2 10.800 1-1/4 1 11-1/2 11.500 1-1/2 1 11-1/2 11.500 2 1-1/8 11-1/2 12.930 --------+----------------+-------------------+----------------
To acquaint the beginner with iron pipe work, the following exercise is given. In it there are a great many of the actual problems that come up when the pipe is put in on a job. This is the last exercise that is required in this book. The sketch shows clearly just what the job is and below I have gone over each operation that is necessary to complete the job.
[Illustration: FIG. 67.]
MATERIALS NECESSARY.--Six feet of 1-inch black pipe; four 1-inch black ells; two 1-inch tee; one 1-inch right and left coupling; oil.
TOOLS NECESSARY.--Two 14-inch pipe wrenches, vise, pipe cutters, stock and 1-inch follower right and left die and reamer.
The vise is made secure on a bench or post, care being taken before it is put in place to provide room enough to swing the stocks. A length of 1-inch pipe is put into the vise and the vise clamped around it. The end of the pipe that is to be threaded should stick out through the vise about 9 inches. If there is a thread on this end, the dies should be run over it to make sure that it is a standard thread and to clean the threads. Before proceeding further with this exercise the dies and stocks will be described and their use shown.
DIES.--A full set of dies is taken. The full set of stocks and dies is composed of right and left dies from 1/8 inch up to 1 inch, with a guide for each size, also a small wrench with which to turn the set screws. The dies come in sets, two in a set. These are the Armstrong patent that I am describing. Take the stock and the handles, and a set of 1-inch right dies with the guides out of the box. The dies will have marked on them 1" R (if 1-inch left were wanted, the mark would be 1" L). The set screws are taken out of the stock and the dies inserted in their proper place. There is a deep mark on the edge of each die and under it a letter S. This letter means "standard." This mark on the die is set even with a similar mark on the stock and when the set screws are in place and tightened, a standard thread will be cut. There is an adjusting screw on the stock to make the proper adjustment on the dies.
STOCK.--The stock is taken and the handles are put into it. There are two sets of set screws on the stock, one set for holding the dies in place and the other set for adjusting the dies. On the stock there is a deep mark to correspond with the standard thread mark on the dies. On the opposite side of the stock there is a place for the follower and a set screw to hold it in place. After the stocks have been looked over and examined thoroughly, the 1-inch right dies are taken and inserted. Then the 1-inch follower is put in place. The tool is now ready to cut a 1-inch thread. Now take a piece of 1-inch pipe at least 15 inches long and put it in the vise, letting it extend out from the vise about 9 inches. The stock is now taken and the follower end is put on the pipe first and the dies brought up in place to cut. The end of the pipe is allowed to enter in between the two dies so that the teeth of each die rest on the pipe. Now, holding the handles of the stock about 6 inches from the body of the stock and standing directly in front of the pipe, push and turn to the right at the same time and the dies will be started. Now put some oil on the dies and turn the stock, taking hold of the ends of the handles and standing at one side.
The dies are run up on the pipe until the pipe extends through the face of the dies one thread. Oil is put on the pipe and the dies at least twice during the cutting. When the thread is long enough the stock is turned back a little and then forward a little and the loose chips are blown out from between the dies and pipe. If the dies are set right, a good clean standard thread will have been cut. This thread can now be cut off with the pipe cutters.
PIPE CUTTERS.--To cut pipe with a one-wheel pipe cutter is a simple matter. I will not dwell at length on the cutter itself. There are one-wheel and three-wheel cutters. We will use a one-wheel cutter tool. This cutter is forced into the surface of the pipe with a set screw having a long tee handle. The pressure that is brought to bear on the pipe while being cut is sufficient to cause a large burr to form on the inside of the pipe. Sometimes the pipe is completely crushed and rendered unfit for use. Therefore the user of these cutters should exercise care when cutting pipe. The pipe is put in the vise and the cutters are so put on the pipe that the pipe will be between the two rollers and the cutter wheel, the cutter resting on the mark that indicates the point at which the pipe is to be cut. The handle is screwed down and the cutters turned around the pipe; each time the cutters make a complete turn the handle is screwed down more. This procedure is continued until the furrow has been cut clear through the pipe.
CUTTING AND THREADING NIPPLES.--Nipples are short pieces of pipe threaded on each end. Pieces of pipe longer than 6 inches are not called nipples. When a nipple is so short that the threads cut on each end meet in the center of the piece, the nipple is called a "close nipple." When there is a space of about 1/4 inch between the threads, it is called a "space or shoulder" nipple. To cut and thread these nipples a nipple chuck or nipple holder is necessary.
[Illustration: FIG. 68.--Nipple chuck and nipples.]
NIPPLE HOLDERS.--Take a piece of 1-inch pipe about 12 inches long and on one end cut a thread that is 2 inches long. Take a 1-inch coupling and screw it on this end until the end of the pipe is almost through the end of the coupling. At least four threads should be allowed at this end of the coupling. Now we have a piece of pipe 12 inches long having a thread 2 inches long on one end with a coupling on the thread. This is called a nipple holder. Now, to cut a nipple, cut a thread on a piece of pipe and cut the pipe off at any desired length, say 2 inches. Put the nipple holder in the vise with the coupling out from the vise about 8 inches. Take the 2-inch piece of pipe with a thread on one end, screw this thread into the coupling until it touches the pipe that has been screwed through from the other end. Now the stocks having the 1 dies and the follower in are put on the pipe. The follower will not go over the coupling, therefore take the follower out of the stock. Now the stock will slip over the coupling and the thread can be cut. With this procedure a nipple of any length can be cut.