Card values are for cold water and liquids. For the new iron pipe: 0.8, for the old iron pipe: 1.25 loss should be calculated.
This ratio should be calculated as 1.70 in pipes with rust. EXAMPLE: Flow rate Q = 500 l / min, new iron pipe diameter 80 mm, length 50m Find flow rate on horizontal axis, follow DN 80 mm intersection vertically, find friction loss from vertical axis. HV = 4.6 m each 100 m pipe HVI = 4.6 x 0.8 = 3.68 m / 100 (iron pipe) Let's apply the formula to the actual values.HVII = 3.68 x 50: 100 = 1.84 m (for 50 m pipe) Flow rate is calculated to find the point of intersection, values are set up between curved lines about 1.5 - 2 m- / s. C = about 1.7 meters / second | 
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