Springs (see also spring backing, buckling strength). The latest editions of the following standards must be observed when designing, calculating and manufacturing helical compression springs for mechanical seals:

DIN 2076, Round spring wire; sizes, weights, tolerances

DIN 2089, Part 1, Cylindrical helical compression springs made of round wire and rod; calculation and design

DIN 2090, Cylindrical helical compression springs made of flat steel; calculation DIN 2095, Cylindrical helical compression springs made of round wire; quality specifications for cold-formed compression springs DIN 17224, Spring wire and spring strip made of stainless steels; technical terms of delivery

L₀ = free length

L₁ = (nominal) mounting length at which the resultant spring force is F₁

L_n = minimum permissible mounting length with the reference spring force F_n

L_c = solid length (smallest length of spring:
all its coils are compressed)

s₁ = spring excursion with L₁ and F₁

s_n = maximum permissible spring excursion

s_c = maximum spring excursion

F₁ = (nominal) spring force at which the mounting length is L₁, and the spring excursion is s₁

F_n = spring force at the minimum permissible mounting length L_n and the maximum permissible spring excursion s_n

D = mean coil diameter

d = wire diameter