By means of a contact-free pyrometric level detection from the outside of a reference tube three measured values can be read out continuously while the process is running:
The continuous pyrometric fluid level detection permits the instrument to keep constant the distance between the blow in tubes in respect of the liquid surface (“Blow in distance”); as a consequence an optimal blow-down rate is maintained during the entire process of evapo-ration.
The accurate control of the fluid temperature as well as of the circulating gas and of the “Blow in distance” allows the user to run reproducible methods on the VAPORNADO® Plus.
At the beginning of the process, the instrument is automatically purged with an inert gas such as nitrogen. This reliably protects compounds which are susceptible to oxidation. It also avoids the formation of vapor mixtures with oxygen. During the process it is possible to repeat the purging with nitrogen at regular intervals.
As the VAPORNADO® Plus is working with an inert gas in a closed cirquit only small amounts of inert gas are consumed for purging at the beginning of the process as well as during the repeated purging.
As the solvent vapors are extracted by suction out of each tube separately there is no risk of cross-contamination. In addition there is a constant by pass flow from the outside of the tubes to the inside, which avoids solvent vapors occurring in sample chamber (outside the tubes).
A set of standard blow-down methods for common solvents is stored in a method repository. Based on these data mixtures of solvents may also be evaporated. Individual methods may be created and stored.
A method also defines an exact procedure at the end of the evaporation process based on the fluid level. This allows the halting of the process after both partial as well as after entire evaporation. Partial evaporation may be useful e.g. to evaporate acetonitrile from aqueus samples prior to lyophilisation.
The VAPORNADO® Plus is equipped with a powerful condenser in order to dry the circulating gas efficiently. This allows an optimal uptake of solvent vapors from the liquid surface of the samples in the tubes. An automated defrost function, which is started at regular intervals, retains the condensation efficiently in the case of freezing solvents such as water.
