NBN EN 15800:2009

This European Standard applies to cylindrical helical compression springs made of round spring wire. Cold coiled compression springs can be made with wire up to about 16 mm diameter. (See also EN 13906-1).
NOTE For springs with wire diameter upper 16 mm up to 20 mm see Annex A
Cylindrical helical springs made of round wire from European Standard materials are subject to the limiting values in Table 1 (see also Annex A):
Table 1
Characteristic Cold coiled compression springs
Wire diameter 0,07 mm ≤ d ≤ 16 mm
Mean coil diameter 0,63 mm ≤ D ≤ 200 mm
Length of unloaded spring Lo ≤ 630 mm
Number of active coils n  2
Spring index 4 ≤w ≤ 20

A specification for the parameters of cold formed helical compression springs is given in Annex B.