Masterpiece

Masterpiece
Problems of distribution system are better known to the maintenance person. He has to do trials and see that the things are set right. He has not to design but convince the simpler methods to the lower staff. In many cases lower staff has the solution. It has to be given correct shape. The background of the process has to be understood. Masterpiece is one such solution. It has not appeared in the books. Seniors do not deny its credibility, but it is not of value to them. Masterpiece has been tried at number of places. It was required to be kept as secret as it is not commonly acceptable. But when results were seen the details were thought of. Masterpiece has no design. Its use is based on experience. On the other hand orifices had some design. The use of orifices was not encouraging. It needed frequent changes. Replacement was not easy. Orifices were struck at valve points only. That is at initial stages only the constriction was proposed. Masterpiece has choice of location. It disturbs continuity of flow. New hydraulics starts from masterpiece and hence, it is more successful.
Concept:
For the design of pipelines in the gravity system, the network is indeterminate, but with some assumptions it can be converted into determinate functions. But there are limitations. While calculating demand, population is multiplied by average LPCD rate. Some peak factor is also considered. System, on this assumption, is required to operate 24 hours, but in practice it does not act accordingly.
System flow is decided by the gravity available and not by the drawal requirement. Hydraulic design does not consider this aspect. It is seen that many a times the velocity of pipe flow is much more than required. This situation is particularly on the sloping ground. Normally from storages outlet diameter is larger one and the resulting drawal capacity is extraneous. On slopes it increases further. On plains, however, the velocity is again slowed down. Hydraulic statement does not take any cognizance of these differential velocities. It calculates the single resultant velocity for the pipe diameter for a particular net head loss. This velocity is irrespective to the length of the pipeline, if minor frictional losses are neglected.
Thus, for long length velocity function is different at different section. The phenomenon is predominant in case of initial empty lines. The chances of emptying the pipeline, in gravity conditions, are frequent. For such conditions, if velocity is required to be controlled, there should be some separate efforts. Such efforts are fruitful with the use of some pipe pieces in the system. Trouble-some gravity system can be easily stabilized with the use of these pieces of pipes and hence, they are termed as master pieces.
What is the trouble in gravity systems? When there is velocity difference in different sections, then naturally a slow moving water column will act as the obstruction to the speedily moving water column. A return wave is expected, at such points. Further, water is heavier than air. On slopes, water gravitates faster. To some extent air also moves downwards with the sweep of water, but gets compressed in the run. It tries to get way through the upper portion of the pipeline. With additional water getting down, equivalent quantity of air wants to go out of system.
For example, suppose 300 mm dia. Pipeline, 600 m in length is continuously sloping at the total loss of head of 30m. The remaining length is flat. Velocity in the sloping portion is of the order of 10 m/sec. Final, resulting velocity is only 0.8m/sec. This indicates that, water column of flat region is comparatively at rest; and hence, tries to obstruct flow impact on slopes. To have the same velocity either pipe diameter has to be reduced or valves are required to be operated. But valve operation can not be relied upon. Instead, pipe diameter can be reduced. It can be reduced at salient points. With some calculations, the diameter reduction can be arrived at, keeping outer diameter same i.e. 300mm. Any lower diameter, say 100mm, 150mm, etc. can be introduced inside. Annular space can be concreted. Minimum length of such piece should be 20 to 30 (d), where d = dia. of smaller pipe. Such concreted piece shall be introduced in the system. Then the same line functions in a different way. It, not only reduces the velocity, but eliminates the troubles due to air blockage. Air can be vented smoothly. Pipe breakage is minimized. Such an exercise can be done on site with very minor set of calculations. Such masterpieces can be used with the combination of air vents, and then the system works very smoothly.
Construction:
For C.I., A.C., and P.V.C pipe lines; approximately 2.5 m length of pipe pieces are used. Outer pipes are equivalent to original pipe diameter. Calculated smaller diameter pipe can be put up-right in the outer pipe, kept vertically. Annular space is concreted and cured. The piece is inserted at suitable locations. Working is checked. If required, some range of such pipe pieces be kept ready and shall be laid along with pre-decided locations of the pipeline to get the required results.
For deeply sloping lines, a regular smaller diameter pipe line is laid and connected to main line after the sloping portion. End of main line is kept open to air and only the smaller diameter pipe is connected to the outlet. Open end works as the natural air valve. Its working is very much satisfactory.
Masterpiece is hidden piece in the system and can not be identified. Externally main pipeline is similar. Jointing system is also as per main line. The master piece once fixed and suited in position works smoothly. It needs no operation. It has no moving parts. Its location should be noted.
Utilization and advantages
Such masterpieces are found very successful in the gravity systems. This has the utilization in distribution system, feeder mains, and Gravity mains. Associated with air shafts the working is very fruitful. The locations can be understood by the lower staff. Introduction is very easy. It needs practically no calculations, if two, three sample trials are taken. The pieces can be prepared easily on site. It needs no extra fittings. The pieces are sturdy and need no maintenance once fitted.