This part of ISO 15859 specifies limits for the composition of helium and establishes the sampling and test requirements applicable for the verification of the helium composition. This part of ISO 15859 is applicable to helium, used in both flight hardware and ground facilities, systems and equipment, of the following types and grades. — Type Ⅰ: gaseous — Grade A: purging and pressurizing helium; — Grade F: purging and pressurizing helium; — Grade J: purging and pressurizing helium; — Type Ⅱ: liquid — Grade A: purging and pressurizing helium; — Grade F: purging and pressurizing helium. This part of ISO 15859 is applicable to influents only within the specified limits herein. This part of ISO 15859 is applicable to any sampling operation required to ensure that, when the fluid enters the launch vehicle or spacecraft, the fluid composition complies with the limits provided hereafter or with any technical specification agreed to for a particular use.