Potassium fluoride,anhydrous
           Potassium fluoride,extra pure
           Potassium fluoride,Granular
           Silicon Dioxide
           Hydrofluoric acid
           Synthetic Cryolite
           Potassium Fluoaluminate
           Ammonium bifluoride
           Potassium Bifluoride
           Aluminium fluoride
           Sodium fluoride
           Potassium Fluorosilicate
           Fluorosilicic Acid
           Sodium silicofluoride
           Potassium Hydroxide Flakes
           Magnesium Fluoride
           Magnesium fluorosilicate
           Barium Fluoride
  News Center

First, stable, less volatile, liquid at normal temperature, density greater than water.

Second, does not react with hydrofluoric acid, insoluble in water, the water will be distinct layers or HF solution.

Thirdly, preferably non-toxic and non-corrosive.

The answer is dichloromethane or dichloroethane or chloroform, they are not react with a hydrofluoric acid solvent and has a density greater than water.

Hydrofluoric acid crude reaction gas from the reactor output by pre-purification, purification tower dust after the addition of H20, via a secondary storage HF condenser is condensed and liquefied in the crude HF sump, the pump pressure into the refined crude acid distillation column to remove heavy components, re-entering the degassing tower to remove light components SO2, SiF4, CO2, O2, N2, AHF finished by distillation after acid cooler into the AHF testing tank, after inspection by the pumped liquid to AHF large storage tank.