How often should the ANKOM Dryer Filter be replaced?

Replacement of the dryer completely depends upon how often it is used to dry hydrolysis samples. The filter should be changed when the filter bags do not dry sufficiently after hydrolysis at 110°C for three hours (adding pH paper in the desiccant pouch will indicate volatile HCl acid presence).  

Another indication the HCl filter needs to be replaced is when HCl fumes are not being captured. Place a piece of litmus paper on the top of the filter and observe for color change consistent with the presence of acid.