During hydrogen permeation, molecular hydrogen (H2) separates into two hydrogen ions (H+) that are now tiny enough to slip through the voids between the grains in the stainless-steel diaphragm, where they can reform as hydrogen bubbles in the fill fluid. The pressure buildup in the fluid created by the hydrogen bubbles affects the span and zero calibration of the sensor, and might reach the point of cracking the diaphragm.