It is often said that to select the best impregnation process “let the parts talk”. Do these parts have a tight or difficult pressure test requirement? Are they limited by print to only one cycle of impregnation? Are they highly machined with tapped holes and/or small passages? Will they be immediately pressure tested and built-out into final assemblies after impregnation? All these factors will point toward choosing the best process.
Vacuumimpregnation generally follows the same four steps (see also animation by Godfrey & Wing):
- Impregnation-Impregnate the sealant into the porosity/leak path using vacuum (and pressure).
- Excess Sealant Recovery-Remove excess sealant through gravity, rotation or centrifugal force.
- Wash/Rinse-Wash residual sealant from the part's internal passages, taps, pockets and features.
- Cure- Polymerize (change the liquid to a solid) the impregnated sealant in the leak path.
With this understanding, there are three viable impregnation methods that can occur during the impregnation step:
- Dry Vacuum and Pressure (DVP)
- Dry Vacuum (DV)
- Wet Vacuum (WV)
Vacuum Impregnation Equipment