This part of ISO 14951 specifies limits for the composition of helium and test methods for verification of helium composition. This part of ISO 14951 is applicable to helium of the following types and grades, intended for purging and pressurization of propellant systems of space systems:

• type I: gaseous
  • grade A: purging and pressurizing helium;
  • grade F: purging and pressurizing helium;
• type II: liquid
  • grade A: purging and pressurizing helium;
  • grade F: purging and pressurizing helium.

This part of ISO 14951 is applicable to helium used in both flight hardware and ground facilities, systems, and equipment. It is applicable to influents only to the extent specified herein.