Vacuum Impregnation Process

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):

  1. Impregnation-Impregnate the sealant into the porosity/leak path using vacuum (and pressure).
  2. Excess Sealant Recovery-Remove excess sealant through gravity, rotation or centrifugal force.
  3. Wash/Rinse-Wash residual sealant from the part's internal passages, taps, pockets and features.
  4. 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:

  1. Dry Vacuum and Pressure (DVP)
  2. Dry Vacuum (DV)
  3. Wet Vacuum (WV)

Additional references:

Vacuum Impregnation Equipment

Movie 1