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Electric Thawing of Water Pipes
An Easy, Simple, and Inexpensive Application of Electricity to an Every-day Service in the Winter Season
By GEORGE ETHELBERT WALSH
T is only quite recently that a commercially practicable method of thawing out water pipes by means of the electric current has been devised. The costliness and clumsiness of former methods for a long time seemed insuperable obstacles, but these difficulties have at last been overcome, and a simple, efficient, and comparatively cheap apparatus put upon the market.
The damage due to frozen water pipes in our Northern cities is annually very great. The cost of thawing out pipes by the present clumsy methods used by plumbers, is almost as annoying as the freezing. The work of digging down to pipes and applying heat directly is slow and costly; and the injection of steam through a rubber tube which is pushed up the frozen pipe as far as it will go, is almost equally expensive and unsatisfactory. The ability to thaw out pipes quickly and effectively is the chief virtue of any system.
Gas pipes freeze up almost as readily as water pipes in extremely cold weather; and where householders depend upon gas for cooking, the trouble causes endless inconvenience. Both gas and water companies have encouraged every effort made to perfect a system of reaching the pipes with direct heat which would thaw out the pipes quickly and effectively. Electricity is apparently the only agent that can solve the problem.
New Method Successfully Tested
The success attained by the new method has been phenomenal, as demonstrated by a number of tests made in various cities of New Jersey during the winter of 1904-05. Over 2,000 water and gas pipes were electrically thawed out in the city of Newark, 200 in Harrison, 130 in Jersey City, 125 in Hoboken, 102 in Passaic, and over 500 more in
other towns and cities of the State. The pipes were thawed out under nearly all conditions of weather and physical surroundings. roundings. Some were laid close to the surface, and others far down below, while a few were in conduits laid below the city pavements, and yet others in galleries supposed to be proof against freezing weather. The success was so great that provision was made to carry on the work on a much larger scale during the present winter. The time required for thawing out the pipes depended upon their size and the conditions under which they were treated. While it took upward of three hours to thaw out one 6-inch main, it was found that two men with a single outfit could thaw out from 10 to 200 pipes in each working day. The charge made for each pipe varied also according to different conditions, the average for each case being from $4 to $15, according to the number of connections made and the size of the pipes.
Portable Transformer Outfit The outfit used in the Jersey cities was mounted on a wagon containing a 300light transformer wired to a wooden rack, and some 500 feet of wire. The wagon was drawn up before a building under an electric-light pole. A wire was connected with the overhead circuit, and current conducted to the transformer. The primary fuse-boxes were located on one side of the transformer, and a heavy knife switch was attached to the bottom of the wagon.
When the pipes of a single dwelling were to be treated, the primary leads to the overhead circuit were connected, and the primary fuses inserted. Then the two heavy wires mounted on reels back of the wagon were run out, and one end connected to the water pipe inside of the house, as near the cellar wall as possible,
the other end being connected either to the nearest hydrant or curb-box. Experience showed that a number of houses could be treated at the same time; and, by connecting them in series, time and labor were saved. In some instances as many as twelve and fourteen were treated at one time, which were thawed out as easily as a single pipe, the time required being, however, a little longer. Another saving of time and labor was found in extending the secondary leads. By this method
TRANSFORMER FOR THAWING OUT WATER PIPES ELECTRICALLY. A-Complete instrument. B-Same with switchbox removed.
the wagon had to move less often; and on one block, as many as thirty pipes were thawed out without moving the wagon to make new connections overhead.
About 3,000 pipes were thus thawed out last winter in the New Jersey towns lighted by the Public Service Corporation, the gross revenue from the work being $12,000. The service was so appreciated that the demand far exceeded the ability of the company to meet it, and this winter the service has been greatly increased.
Charges made by plumbers for thawing out frozen pipes frequently range from $25 to $50, while the cost to gas companies of thawing out their pipes
A portable transformer outfit for thawing out frozen pipes has been made for quick and easy connection with alternating-current circuits, with adjustments. over a wide range of voltage. Operating under circuits varying from 2,000 to 2,300 volts, 60 cycles, the secondary voltage and current for thawing pipes can readily be adjusted from 0 to 75 volts and from 0 to 400 amperes. This easy adjustment of the secondary voltage and current makes it possible to use the outfit for nearly all classes of work. The whole outfit weighs less than 2,000 pounds, and it can be mounted on either a wagon truck or sleigh.
The transformer is light and compact, and stands on three legs, with a closed
magnetic circuit at the ends. The leads of the primary coil are connected to a switchboard on the side of the transformer; and the terminals of the secondary coil are brought to heavy lugs at the end, from which cables are run to the pipes. In thawing street mains sufficient voltage and current can be obtained by connecting two adjoining hydrants as terminals, but service pipes are thawed out by using the house faucets and the nearest hydrant as terminals.
Precautions Against Danger There is only one danger in using a
shunt, there is no absolute rule or data to guide the workmen in their application of power for the different size pipes. Usually the practice is to start with the shunt completely lowered, so that the minimum of voltage and current is first delivered. Then, by gradually increasing the amount until the water is thawed, little damage is caused.
In a frozen water pipe 40 feet long and three-quarters inch thick, about eight minutes are required to thaw out when 50 volts and 300 amperes are delivered. An increase in the length of the pipe increases the time and voltage only slightly.
transformer outfit of such heavy current as this, but that can be easily obviated where the workmen understand their business. Unless good connections are made, the water faucets may be burnt out by the heavy current, or the hydrants and pipes be disfigured. Several such accidents happened last winter in the towns. and cities of New Jersey where the transformers were employed. The accidents were found to be due to using too little resistance and too small a transformer.
The chief problem confronting the operators is to ascertain the approximate amount of current needed for each pipe. While the complete outfit permits of ready adjustment of voltage and current by simply changing the position of the
Thus 100 feet of the same pipe can be thawed out in 10 minutes with a voltage of 55 and 335 amperes, or a 250-foot pipe can be thawed out in 20 minutes with 50 volts and 400 amperes. An increase in the size of the pipe increases the amount of current to 500 amperes for each additional quarter-inch in diameter.
Value of Large Current
Some experiments to test the relative efficiency of voltage and current were made. Thus, in a one-inch pipe 700 feet long, a voltage of 55 and current of 175 amperes were delivered, and it required five hours to thaw it out through its entire length. In another test a voltage of 55 and current of 260 amperes thawed
out a pipe 1,300 feet in length and 4. inches in diameter in three hours. A still further emphatic illustration of the value of large current, was shown in a test with an 800-foot pipe ten inches in diameter. This pipe was thawed out in two hours by a voltage of 70 and 400 amperes. The full voltage of the secondary coils is thus sufficient for the largest size of pipe. With a voltage of 75 and current of 400 amperes, a tenfoot pipe 1,000 feet in length could be thawed out within a trifle over two hours.
For special emergencies when fire hydrants are frozen up, it is possible to increase the current beyond the rating given for ordinary uses. It is possible to raise the current on cold days to 800 amperes for ten or fifteen minutes at a time, without causing trouble.
Advantages of New Method The whole plan of thawing out water and gas pipes by electricity is clean, cheap, and expeditious. There is no digging up of extensive areas of soil, which in the winter season means long preliminary heating of the frozen top soil with fires. The work can be done wherever electric current can be obtained in the street or nearby houses. Apparatus is made for tapping 2,400-volt alternating overhead circuits, the temporary connections being made on live wires. To do this, however, the insulation must be scraped off, and the wire tapped directly to the live wire. This naturally limits the field of operation to the electric light or railway operating companies, or to private companies with certain privileges obtained from the electric light corporations. To make connections with the live wires as infrequent as possible, wires 400 and 500 feet long are used. The houses on a large block can thus all be reached from one tapping.
A portable gas-engine-driven dynamo has further helped to solve the problem in towns and cities where electric services are far from satisfactory. In one of these portable units, a small gas engine. of 12 to 15 horse-power is direct-con
nected to an 8- or 10-kilowatt generator delivering 600 amperes at 12 to 15 volts. Such a portable outfit would be sufficient for all service pipes, and could thaw out from 50 to 200 pipes a day according to their size and distance apart. Where the frozen pipes were located within restricted areas so that they could be connected in series, far more than 200 could be thawed out each working day. In emergencies a double crew could work at the plant, and in one day and night upward of 600 or 700 pipes could be successfully treated by such a small, compact, portable unit.
A portable electric thawing plant has also been in use in New York State, operated by a 12-horse-power gasoline engine which propels it along the streets as needed. It is really a gasoline automobile. On the front part of the machine is mounted a 7-kilowatt dynamo developing 600 amperes at 12 volts. The dynamo is connected by a belt to the driving gasoline engine. When the automobile stops, the work of connecting the belt. with the dynamo shaft is simple and quick; and within less than a minute, everything is ready for thawing out the pipes.
In fact, the electric current is ready before the men have adjusted their wires to the terminals. This self-contained and self-propelling outfit is of particular service in small country towns and villages where electric current is difficult to secure in all places when needed.
In applying the current to the pipes, the ice and cold water keep down the heat so that there is little danger of melting the pipes until the water is running once more. Then a heavy current maintained for any length of time would boil the water and melt the pipes. The melting point of lead pipes is 617° F., but it is rarely that the temperature of the pipes has reached 100° or higher. It would, however, be possible to raise the temperature very quickly after the ice is once thawed; and without experienced operators who know when to stop the current, damage might easily be caused that would far more than offset the saving.
The Latest Evolution in Automatic Devices that Lessen Labor and Abolish Worry
By THOMAS L. WAITE
ERLIN, the German capital, possesses more "Automats"-automatic machines-than any other city in the world, and they are all of some practical benefit and use. They have "automat" beer halls, where a nickel-in-the-slot brings you your stein of foaming beer; "automat" cabs, where a machine called a "taximeter" registers the fare to be paid and makes it almost impossible for "cabby" to "knock down" on his passenger. There are "automat" theaters, where the nickel-in-the-slot starts a whole show of several acts and many scenes; "automat" restaurants; and "automat" bootblacks. These latter are peculiarly unique, and, though not unknown in America, they are every-day necessities in Berlin.
The Automatic Restaurant The "automat" restaurant is not only a labor-saving device, but it is a headache-sparing institution, as it does away with the waiters, who make you do the waiting, and gives an instantaneous service. You are your own waiter; and consequently there are no fees, for you cannot conscientiously tip yourself, however self-gratulatory may be your mood. You select what you want, drop your nickel in the slot, and there you are!
Of course this Automat of the Dinner Table is an unintelligent mechanism of man's invention, ingeniously worked by electricity. Cabinets with glass fronts line the walls; and through these glass fronts are to be seen rows and rows of little elevators, with the slots and mech