The quality of one produces is a function of the products used.
These products are very thin and very fragile. If they these products are to separate different items (different dimensions) or 2 fluids or a media, the manufacturer has the obligation to ensure that these are manufactured to the highest level. A leak test is conducted on hollow fibers to ensure that they are breached or broken. When it comes to flat sheet membranes these have to be characterized to verify that the pore sizes are within the tolerances of the norm.