The operator runs the nozzle along the seam edge at close range; where the bond is incomplete, the air lifts the top sheet and the edge flutters or the sound changes. It is a quick nondestructive check for thin, flexible sheet such as PVC and some polypropylene liners, but not for stiff HDPE. It finds edge gaps, not leaks across the full width of a seam.
Air lance the PVC seams before they cover it, and mark anything that lifts.
Also heard as
- air lance test
- air lancing
Related terms
PVC
Polyvinyl chloride: a flexible, plasticized geomembrane that folds and seams easily, used in ponds, canals and water features.
Vacuum box
Clear-topped box pulled to a vacuum over soapy geomembrane so leaks in seams and patches show up as bubbles.
CQA
Construction quality assurance: independent monitoring and testing that a geosynthetic system was built as designed.