How Maps Speed Up Valve Closing

How Maps Speed Up Valve Closing

Simple System That Would be Applicable to All Sizes of Water Departments—Maintenance of Valves in Good Condition—Efficient Mechanism to Rapidly Close the Valves

THE maintenance of a system recording the exact location of shut-off valves in a water works distribution system would seem to be of the first importance, and vet, strange to say, it is one of the most neglected matters connected with water department practice. This, combined with the keeping of these valves in good operating condition and the provision of proper mechanism to quickly close them in the event of a break, is a prime necessity of every well regulated water works. The suggestions contained in Mr. Brush’s article are, therefore, particularly valuable to superintendents.

Fig. 1—Contrast in Operation Between Valves Before and After Cleaning There are two 48-inch valves under this street, and neither one could be operated by six men with a 12-foot cross arm, as shown in right of picture. After cleaning exterior moving parts valve to right of picture was easily moved by two men using a short cross arm through head of gate key.

Every superintendent of a water works system has given some thought to the most effective plan for shutting off the important mains in the system under his control, if the necessity should arise, but breaks and other causes for shut offs are so infrequent that it appears to be the exception rather than the rule to find that a definite, easily accessible, and readly interpreted system has been adopted, installed and maintained up to date for the purpose of locating and closing valves to shut off the flow through the larger mains in a water supplysystem. All water works operators will agree that this condition should not exist, and it is the writer’s hope that a description of a simple and inexpensive system will help some fellow superintendents in adopting and suitably maintaining this or some other satisfactorysystem.

The essentials of any system for shutting off the flow through mains are: (a) the determination of the number and location of valves controlling a shut off; (b) the maintenance of all valves in good operating condition; and (c) mechanism to rapidly close valves. Each one of these subdivisions will be discussed separately.

Determination of Number and Location of Valves Controlling a Shut-Off

The system for this part of the work must be one that is easily understood by a man who is not necessarily familiar with the water pipe lay-out, that is readily worked up, and that may be cheaply duplicated. These requirements are all met by the socalled shut-off maps which for several years past we have been preparing to cover all our large mains, which in our system is generally interpreted to be mains 20 inches or larger in diameter. The limiting size of the main to be outlined on these maps for any water works would depend upon the size of the system and the importance of the various mains. A typical shut-off map for two parallel 48-inch mains is shown in figure 2. All these maps are prepared on tracing cloth, the depth of the tracing being 11 inches, with a right-hand binding border three-quarters of an inch wide, so that the print can be held in a standard letter size binder. The length or width of the tracing is usually 8 1/2 inches, but this dimension can be enlarged as much as may be found necessary, and the prints folded to the requisite 8 1/2 inches in width. Several points are speciallyto be noted about this map.

  1. —Only the main or mains involved in the shutoff between two head gates are shown with the valves, air cocks and blow-offs.
  2. —Long sections which do not contain valves are omitted. In the map illustrated two sections totaling 1,000 feet of main have been left out.
  3. —No fixed scale is used, but the plotting is such as to make a reasonably accurate picture,
  4. —All valves, air cocks (other than hydrant air cocks), and blow-offs are located by given distances, which are usually to the nearest foot and measured from reference lines or points which are easilylocated.
  5. —Detail sketches are made when the general scale is too small to clearly show reference distances.
  6. —Number of turns to operate larger valves is given.
  7. —Dates of verification by actual operation of shutdown, and dates when corrections were made are noted.
  8. —Each sheet bears a serial number for ready reference.

It is proposed in the near future to add to the shut-off maps a graphic or tabular record of the normal pressures at hydrants where there are two or more large mains in the same street, for the purpose of determining by the drop in pressure on which main a break has occurred. Frequently in the past it has been impossible to tell, except by a shut-down, which main had broken. The normal pressures would be shown or given in a table so that without difficulty the proper pressure at any time during the twenty-four hours could be determined.

When the outline of the main and approximate location of valves have been placed on the shut-off map, the sheet is turned over to the field force, which goes out and actually makes the shut-down to test the accuracy of the map, and to determine the reference points and distances therefrom to the various valves. The map is then returned to the office to be finished. Thereafter as many prints as may be desired are made, and sets of prints made up covering a district with an index sheet on which reference is made to each map by street location. As these shutoff maps are of usual letter-paper size in one dimension. they can readily be fastened into a binder, and the binder carried in the repair truck or foreman’s car. or other suitable vehicle. As soon as a map is finished it is added to the set of prints of maps previously finished, and a full set can be gradually prepared as time available will permit. Our experience with these maps has led us to the conclusion that they are better suited for general use in pipe systems than any other form we have been able to learn about. This statement is not intended to belittle the advantages derived from a system of field signs or markers placed in the immediate vicinity of each valve, but even with field markers, the shut-off maps are a necessary supplement for accurate and rapid shutdown of any main where there are several connections with such main.

Fig. 2—Shut-off Map for Two Parallel 48-Inch Mains, the Length Covered for Each Main Being about 3,000 Feet

The Maintenance of All Valves in Good Operating Condition

A water valve is a relatively simple machine which will give reliable service for generations, if reasonably looked after. It is a machine, albeit, a very slow moving one, and like all machines must be given intelligent care, and operated’ and lubricated at reasonable intervals. Even if such intervals be a year apart, generally good results can be obtained, but it is desirable that the time interval be six. months rather than a year. Lubrication and clearance of surfaces in contact deservemore attention than has been given to them by manufacturers. A force feed lubrication by means of greasecups could readily be furnished by the manufacturer, but unless the superintendents demand such appurtenances they will not be furnished, and if furnished will be useless unless regularly brought into play. Insufficient clearances are generally found between moving surfaces so that corrosion and dirt will “freeze” these surfaces and prevent operation, even though the contact is between iron and bronze. It has recently been found that 36-inch valves installed within the past two years could not be satisfactorily operated in a year’s time after installation, due to friction and corrosion on contact surfaces on external moving parts. Force feed lubrication would obviate this difficulty.

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The New York valves for a number of years did not receive proper attention, due to lack of force, and our experiences in restoring the large valves to a condition of free operation have strongly brought out these two points. We now have been allowed men specially to operate and repair the large valves, and in a short time all will have been put in good condition. Very recently six men on a twelve-foot bar could not operate either one of two 48-inch valves, but after the outside moving parts of one of the valves had been taken off, cleaned, filed down, and lubricated, the valve could be easily operated by two men using a three-foot leverage. The condition of operation before and after cleaning and lubrication is shown in figure 1.

Mechanism to Rapidly Close Valves

Relatively slow progress has been made in the development of an economical and efficient method of closing water valves. The old hand method isstill in use in virtually all systems, although of late the use of electricity to operate the most important valves has made notable progress. The expense of equipping and subsequently maintaining valves with motor operation attached permanently to each valve virtually precludes the adoption of this method for general use throughout a water system. The most promising system for general use at a cost that makes it feasible for the larger towns to utilize it is the portable mechanism transported on an auto truck and operated by the power of the truck. Boston and Detroit successfully utilize such devices, and other cities are trying them, and with active development by the manufacturer it is believed they can be satisfactorily used in the majority of systems.

Conclusion

No attempt has been made in this article to exhaustively cover the field of valve location and operation, but the writer is hopeful that his fellow water supply workers will give to this subject additional attention and develop a standard of practice far above that which has heretofore prevailed in the majority of both our smaller and larger communities.

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