# Inverted Siphons

When a main dips below the hydraulic grade line, it's referred to as associate inverted siphon. The purpose is to carry the sewer under the obstruction, such as roadway, railway, stream, river, etc. and regain as much elevation as possible. The sewage through such a pipeline (or inverted siphon) will flow under pressure which is greater than atmospheric pressure. Inverted siphons should be resorted to only where other means of passing the obstruction are not feasible, as they require considerable attention in maintenance. As the siphons are depressed below the hydraulic grade line, maintenance of self-cleansing velocity at all flows is very important.

### Inverted siphon Designing

1. The construction of the siphon should be simple.

2. The changes in direction should be easy and gradual.

3. It is necessary to have a seIf-cleansing velocity of 1 meter per second for the minimum flow to avoid deposition in the line.

4. The siphon should have two or three pipes of different sizes, laid parallel so that to the average Hows one pipe comes into service and when the flow exceeds the average, the balanced flow is taken up by the second and subsequent pipes.

5. For the selection of proper sizes of pipes, the minimum average and maximum flows m the sewer should be considered.

6. The total length of each pipe consists of straight lengths and the lengths of fall, bends, and rise. Allowance should be made for loss of head due to bends and due to increased friction on account of roughness in the siphon caused due to sitting in the straight length.

7. The possibility of sitting should be avoided or minimized. '

8. The design of inlet and outlet chambers should allow sufficient room for entry for cleaning and maintenance of siphons.

9. Proper bypass arrangements should be provided from the inlet chamber to the nearby stream.

10. if the length of the siphon is more, hatch boxes at intervals of about 100 m should be provided for the facility of rodding.

### Limitations of Terzaghi Theory

Limitations of Terzaghi Theory The value of the coefficient of consolidation has been assumed to be constant.  The distance d of the drainage path cannot be measured accurately in the field. The thickness of the deposit is generally variable, and an average value has to be estimated.  There is sometimes difficulty 1n locating the drainage face, and sometimes thin previous seams that can act as good drainage faces are missed in the boring operations. The equation is based on the assumption that the consolidation is one-dimensional. In the field, the consolidation is generally 3-dimensional. The lateral drainage may have a significant effect on the time rate of consolidation. The initial consolidation and secondary consolidation have been neglected. Sometimes these form an important part of the total consolidation. In actual practice, the pressure distribution may be far from linear or uniform.

### Types Of Current Collector

Current Collector A current collector is a device used to collect electrical current from a moving conductor, such as a train or a trolley. It is typically used in electric vehicles, such as trains and trams, to transfer power from an overhead power source to the vehicle's electric motor. The current collector consists of a sliding contact, which is often made of carbon or copper, that makes contact with an overhead power source, such as an overhead catenary wire or a third rail. The sliding contact is mounted on the vehicle and is typically in the form of a pantograph or a trolley pole. The pantograph is a device with a metal frame and a spring-loaded arm that presses against the overhead power source. It is raised and lowered by the operator of the vehicle, and as it moves along the overhead power source it maintains contact and collects the electrical current. The trolley pole is a vertical pole that is mounted on the roof of the vehicle and has a horizontal arm that extends out