detank

verb2

1. •
   To empty (some substance) from a tank.

   • During the test, the conformal skin heaters were operated and exercised to simulate various thermal conditions; the cabin was pressurized and depressurized; simulated propellant was detanked; […] — 1974
2. •
   To empty (a vehicle or equipment, or its tanks).

   • The number two oxygen tank in the Service Module could not be detanked properly after the countdown demonstration test. — 1970