Section

A pipe section with a constant internal diameter and constant volume flow is referred to as a partial section.

For the hydraulic calculation, a pipe network must be divided into sections (TS). The condition that the flow velocity must not change applies in sections. At the latest with each branch and with each reduction, but also with a change of material, a new section must be introduced. Sections can be further subdivided for formal/functional reasons, e.g. to clearly designate the type of pipe (distribution, riser, floor pipe, etc.).

For the standardised use of the zeta values (DVGW worksheet W 575), especially on branches, the following definition of sections must be observed:

Branching systems

In branching systems for drinking water cold (PWC) and drinking water hot (PWH), the sections generally begin with the branch/T-piece(ζ value) and end with the straight pipe. An exception is, for example, the last section before the tapping valve(individual supply lines in the PWC / PWH system). Here, the TS ends with the fitting connection, e.g. a wall disc.

Collecting systems

In manifold systems, the section usually starts with the straight pipe and ends in the branch/T-piece(ζ value).