The problem has been that, as helium molecules are smaller than those of any other gas, they also seep out through the fabric much faster. Every fabric ever made allows gas to seep or permeate out to a greater or lesser extent. This “seepage” is actually a bigger problem than leaks and it extends far beyond the aerospace industry, to include anyone manufacturing with plastics, laminates or textiles. This means that testing as part of both development and quality control is essential. Versaperm’s latest permeability meters aim to give a fast measurement that is accurate in the parts per million (PPM) range.
To ensure that airship and textile companies can measure the rates at which atmospheric gasses permeate into the envelope, as well as how fast helium seeps out, the instrument can optionally measure the permeability not just for hydrogen but for virtually every other gas in modern use, including hydrocarbons, solvents, oxygen, carbon dioxide and water vapour.
