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The application of Appropriate Technology

Head Loss Calculator Spreadsheet

Posted on Oct 25, 2011

This spreadsheet allows the user to calculate the frictional head loss (m) for a given flow rate (LPS) and pipe length (m), for a series of different diameter pipes (in). The user can also find the optimum combination of 100m sections of two pipes of different diameters (in) to “burn off” a given frictional head (m). Microsoft Excel...

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Natural Flow Calculator Spreadsheet

Posted on Oct 25, 2011

This spreadsheet allows the user to calculate the natural flow rate (LPS) of any combination of up to 4 pipes of different diameters (in) for given pipe lengths (m) and known head (m). Microsoft Excel Spreadsheet (165KB) *** Note: this spreadsheet contains macros, and you may get a security warning.

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Gravity Flow Spreadsheets & Calculations

Posted on Oct 25, 2011

Articles and spreedsheets to help you with the calculations necessary to design gravity flow water systems.

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Friction Loss Tables

Posted on Oct 25, 2011

Data for frictional losses in plastic pipe Diameter: 13-75mm, Flow rates: 0.06-3.15LPS, Frictional coefficient: C=150 This table is available as a PDF.

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Worked Example 9: Sample Water System Design

Posted on Jun 12, 2011

Numerical Example Figure 22 below shows the topographic survey results for a proposed gravity flow water system. Assuming that the allowable pipe pressure head is 100m, the safe yield from the spring is 0.25LPS and that the design parameters from Jordan are adhered to (see Appendix 4.), design a system that will supply water to the community for the minimum cost. Answer The design of this water system will be approached in the following phases: Requirement for and placement of break pressure tanks. Design of pipe work. Check chosen pipe work for low pressure head parameter. 1. Requirement for and placement of break pressure tanks Consider the control valve at the reservoir tank being closed to begin with. This is the maximum static head condition (Appendix 4 No. 1). All the static heads can be calculated from Equation (35) below: Consider the section of the system from the spring (point 1) to low point 2. The static head is: which exceeds the 100m allowable pipe pressure head given above. Consider the section of the system from the spring (point 1) to high point 3. The static head is: which is within the above limit. Consider the section of the system from the high point 3 to the reservoir tank (point 4). The static head is: which exceeds the 100m allowable pipe pressure head given above. It is clear that the pipes at points 2 and 4 will blow unless we introduce break pressure tanks to relieve the pressure. The first break pressure tank (hereafter BP1) must relieve the pressure at point 2 but still allow the water to flow over point 3. The maximum height (hBP1) we can place BP1 at is given by: so: and therefore: and: so: and therefore: So the height of BP1 must be less than or equal to 150 and greater than 125, to satisfy the conditions. As there will be frictional losses in the pipes we should situate BP1 at its maximum allowable height, which is in this case 150m. This corresponds to a location approximately 225m from the spring tank. The second break pressure tank (hereafter BP2) must relieve the pressure at point 4 but not exceed the pressure head limits in the pipe work between it and BP1. The maximum height (hBP2) we can place BP2 at is given by: so: and therefore: And so: and therefore: So the height of BP1 must be greater than or equal to 50 and less than or equal to 100, to satisfy the conditions. So it will be placed at a height of 70m. This corresponds to a location approximately 2500m from the reservoir tank. The two break pressure tank locations are added to the topographic survey, and shown below in Figure 23. y inspection of Figure 23, the maximum static heads (after the introduction of the two break pressure tanks) are as follows: At BP1: At Point 2: At Point 3: At BP2: At Point 4: All of which are acceptable. 2. Design...

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