What is the nominal pressure (PN) of a valve?

PN:

A combination of letters and numbers used for reference purposes in connection with the mechanical and dimensional properties of piping system components. It consists of the letter PN followed by a non-factorized number.

Note:

1. The numbers following the letter PN do not represent measured values and should not be used for calculation purposes, unless otherwise specified in the relevant standard.
2. The term PN has no meaning except in connection with the relevant pipe component standard.
3. The permissible pressure of a piping element depends on the PN value, material and design of the element as well as the permissible working temperature, etc. The permissible pressure is given in the pressure-temperature rating table of the respective standard.
4. All piping components with the same PN and DN values and their mating flanges should have the same mating dimensions.