What is Bag in Bag out filter system?

It is used to clean the impurities from the process fluid. It is normally used for the filtration of chemical liquids, oils, and others requiring cleanliness levels up to 10 microns or more. These systems are designed to handle fluids with corrosive components present, such as HCl, HF, Sulfuric acid, etc. 

Its procedure whereby material or samples are transferred to (or from) sterile containers. The goal of the process is to prevent contamination during transfer. They may be used for filtering particulate matter, precipitates, or other solids that can lead to sample contamination.