This part of ISO 17491 specifies a method to be performed either at minimum test settings (Method 1) or at

more rigorous test settings (Method 2), for assessing the resistance of a gas-tight suit to outward leakage of

air through, for example, essential openings, fastenings, seams, interface areas between items, pores and any

imperfections in the construction materials.

This test does not simulate penetration by gases in an inward direction. Although the danger to the wearer

arises from leakage in an inward direction, this test method assesses the outward leakage of air after the gastight

suit has been inflated so as to stretch the construction material, thereby enabling the test method to detect

very small imperfections, such as holes, splits or tears.