Technical Booklet N Drainage·Page 11·2.2
Capacity of pipes
Sanitary pipework systems must have adequate capacity to carry expected flow at any point. Where minimum pipe sizes are specified in tables or diagrams, those sizes must be provided, with expected flow based on the type, number and grouping of appliances.
The capacity of a sanitary pipework system should be adequate to carry the expected flow at any point, provided that where a minimum size of pipe is stated in a paragraph, Table or Diagram that size of pipe should be provided. The expected flow depends on the type, number and grouping of appliances and the flow rates given in Table 2.2 should be assumed.
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