Selecting right type of concrete pump using nomograph
One of the major requirement of concrete pumping is to find out suitable pump for particular job. For right type of pump selection using nomograph, following information should be known
1.Require voulme of concrete to be delivered in hours (Cumtr / Hr)
2.Internal diamtere of pipe line
3.Total pipeline length including bends
4.Slump of fresh concrete
Nomograph is design and developed by Swing Stetter, a leading concrete pump manufacturing company, by compiling values over 15 years of concrete pumping jobs in Germany and other countries.It has turn out that even under the most varied site conditions the values recorded on the basis of nomograph and the actual values are in adaquate conformance.The deviations are within the range of 10 %.
As shown in below fig, the nomograph consists of four quadrants.
The upper left quadrant is the beginning and end point of the graph. It shows maximum output, pressure, and power for a specific machine.
The upper right quadrant accounts for the relationship between output of concrete and pipeline diameters.
The lower right quadrant accounts for the resistance to flow of the entire pipeline system.
The lower left quadrant accounts for the workability of the concrete in terms of slump value in mm.
Using nomograph for calculate concrete pump pressure required
In following illustration, following values are considered for concrete pumping job
1. Required output : 40m3/ hr
2.Total pipe line length including bend : 300 mtrs
3. Slump at pouring point : 90 mm
Follow the chart in a straight line from “required output” into the upper right quadrant (shown in above fig.) until you come to the size of the pipeline that you will use. In this example, required output is 40 m3/ hrs and diameter of pipe line is 125 mm. The line starts from point 1 (40m3/ Hrs output) and ends at Point 2. (Intersection of 125 mm Dia pipe line)
The lower right quadrant (shown at right) introduces the pipeline criteria. It accounts not only for the length of the pipeline, but also the number of bends, the increased resistance of flow in rubber hose, etc.Start drawing line from Point 2 downwards until Point 3 (Intersection to 300 mtr pipe length line). For calculating the total length of pipe, following points should be noted.
1. For vertical placing, add 0.25 Bar/ Meter length
2.For each 30 Degree bend, add 1 mtr of pipe line length. e.g. for 2 bends of 90 degree add 6 mtrs length(90 X 2 / 30 = 6)
Lower left corner introduces slump value at pouring point. Tn this illustration, we have considered 90mm sluump.Start drawing line from point 3 towardes left intill it intersect 90 mm slump line. (Point 4)
Upper Left cornet introduces maximum output, pressure, and power for a specific machine. Start drawing line from Point 4 upwards until it intersects Concrete Pressure (Bar) Line. Point 5 in this case.
So pressure required for concrete pumping is calculated as 60 Bars. From this value and considering other values i.e. maximum output, power, cost etc select right pump for concreting job.
Content retrieved from: http://www.probcguide.com/civil-works/how-to-select-concrete-pump-using-nomograp/.