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The application of Appropriate Technology

Articles for Keyword "distribution network"

Distribution Network

Posted on Nov 20, 2011

In this system each family got their own tap that is connected to the reservoir tank using a polyethylene pipe network. The exit pipe work at the base of the reservoir. Making the tapstands. Fixing a t-joint into the distribution pipe work. A finished tap...

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EPANET Program Download And Manuals

Posted on Nov 17, 2011

From the links below you can download the EPANET program for free and also download the EPANET manual. Download EPANET 2.0.1.1 (1.5 mb zip file) Download the EPANET Manual (1 mb pdf file) Download EPANET website can be found at ...

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Fluid Mechanics For Gravity – Flow Water Systems and Pumps

Posted on Jun 5, 2011

A text detailing the design of water systems including the design parameters recommended for a successful and long lasting water supply. Issue 2 May 2003.

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The Anatomy Of A Gravity Flow Water System

Posted on Nov 20, 2011

This section contains photographs that detail the construction of a gravity flow water system for 32 families. The system cost £130 per family and took 30 people 18 days to build. Before the system can be designed the area must be surveyed. The system consists of: A spring tank; A main pipeline, including a pipe bridge; A reservoir tank; A distribution network that leads to a tap at each house. For a gravity flow system to work properly the pipes must run full of water with no air locks. Gravity can then be used to move water, over hills and undulations, between the spring and the reservoir tank. This method works for as long as the spring tank is at the highest point in the system and that there is enough height difference, between the spring tank and the reservoir tank, to give a sufficient flow rate once friction losses have been taken into account. The distribution network also uses gravity to move water to the taps through thinner...

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The Main Pipeline

Posted on Nov 20, 2011

This system has 4 km of pipe. The main pipeline runs from the spring tank to the reservoir tank. Because of the large drop between the spring tank and the pipe bridge PVC pipe (rather than the usual polyethylene) was used to cope with the large pressures. Due to the topography a break pressure tank was not included in the design. A galvanised steel pipe bridge spansa river at the lowest point below the spring tank. The pipes reads for the laying of the pipe line. The PVC (white) and Polyethylene (black) pipe. Laying the PVC mainline from the spring tank to the reservoir tank. Joining two PVC pipe ends on the mainline. Laying the PVC pipes for the mainline. Crossing a river by building a pipe bridge. The finished pipe bridge. The Wash-out PIpe running from the mainline into the river. Building a valve box on the wash-out pipe. The finished pipe bridge, wash-out and valve...

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Water System Design Parameters

Posted on Oct 25, 2011

Condensed from A Handbook of Gravity-Flow Water Systems, Thomas D. Jordan Jnr., Intermediate Technology Publishing. It can be downloaded as a PDF. The following are a list of design parameters that are important in the design of gravity-flow water systems: Maximum Pressure Limits : The taps and valves closed state, should be the maximum pressure condition for the system. Maximum head limits for the pipe work will be used to carry out the calculations. This scenario is used at the start of the design to be able to place any break-pressure tanks that may be required. Safe Yield : The safe yield is the minimum flow from the water source. It is important to not draw more than this supply from the system at any point. If this happens then spring boxes and/or break pressure tanks will run dry and air will enter the system. Negative or Low Pressure Head : If the pressure head (P in the Bernoulli Equation) becomes negative at any point in the system then two things may happen. Firstly a siphon effect is occurring which is trying to suck water into the system. This is undesirable as polluted groundwater may be introduced into the system. Secondly, large negative pressures can cause air to come out of solution in the water and cause air-blocks. Jordan [P.52] suggests that the pressure head should, if possible, not fall below 10m (98100 Pa pressure) anywhere in the system and never go negative. Velocity Limits : The flow velocity in the pipelines should not be to great as particles suspended in the water will cause excessive erosion. Also if the velocity is too low then these particles will settle out of the flow and may clog the pipes at low points. This then requires washouts at low points in the system. Jordan [P.53] suggests that the minimum velocity should be 0.7m/s and the maximum 3.0m/s. Natural Flow : Natural Flow (see Section 8 i)) may be allowed to occur in the system at some sections of pipe. Natural flow can be problematic in that the water velocity may exceed the limits set in parameter 4 above and/or increase the flow rate above the safe yield parameter 2. Close attention should be made to these situations. Residual Head : The residual head at a tap stand or valve is important. If it’s too high it will cause erosion of the valve and if it is too low then the flow will be minimal. Jordan [P.141] suggests the following limits : Absolute minimum : 7m Low end of desired range : 10m Most desirable : 15m High end of desired range : 30m Absolute maximum : 56m Air-blocks : These occur when there are topographic features between the source and the collecting tank that are lower than the collecting tank. Energy is lost from the system as these air-blocks are compressed and can result in no flow. Jordan [P.55] gives the following design practices to avoid air-blocks : Arrange pipe sizes...

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