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DIN 1988 T3 / Maximum flow rate  / Principles of calculation / Calculation guide / Software

DIN 1988 T3

Part 3 of the DIN 1988 (Technical Rules for Potable Water Installations) specifies the calculation principles for the determining of the pipe diameter.

The determining of the pipe diameter is based on the calculation of the pressure loss in pipes.

Beside the diameter the pressure loss depends on the length of the pipe, the pipe material and on the flow rate, dependent on the quantity and size of the water points to which the pipe is connected.

The basis for determining the maximum flow rate should be calculated on  the desired flow rate of each water point. The simultaneous use resp. the peak pressure of flow of an installation part has to be determined by taking the calculation values from DIN 1988 T 3 as a basis.

Maximum flow rate

A further criterion for the selection of the pipe diameter is the maximum permissible flow rate. Because of sonic reasons and for the limitation of water hammer, the calculated flow rate may not exceed the values of the table below.

aquatherm_green_pipe_criterios_instalacion_calculo_tabla1

Principles of calculation

To determine the pipe diameter in potable water networks of buildings numerous principles of calculation are necessary. The revised version of DIN 1988 provides a simplified and differentiated method of calculation.

The simplified method is suitable for clearly arranged pipes i. e. in residential buildings. The differentiated method includes all pipes and local resistances and offers the highest accuracy as well as the most accurate approximation of real operating conditions. The determining of the pipe diameter requires the following data:

  • Minimum gauge pressure of supply or pressure in flow direction behind pressure reducing or boosting valve
  • Head variations
  • Pressure loss due to apparatus i. e. watermeter, filter, softening installations etc.
  • Minimum flow pressure of the water point applied
  • Pipe friction factor of the used pipe material
  • Coefficients of loss for fittings and pipe connections

Calculation guide  /  Software

The potable water network calculation acc. to DIN 1988 is normally made with the assistance of software.

aquatherm offers the independent and easy to use calculation programm “liNear”, which can be ordered directly with – or without – training at aquatherm.

For our Dendrit - Customers:

aquatherm naturally still offers you qualified support with your Dendrit - Software.

For both, liNear and Dendrit, please call our information service:

+ 49 (0) 2722 950-200

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