Apr 03, 2021 · Flat bottomed EPA vials are made of chemically inert clear Type I borosilicate 33 expansion glass, or for light-sensitive samples, of amber 51 expansion glass. Remember, as with all Pacific Vial glass vials, Caps are sold separately. EPA GLASS VIAL QUALITY CONTROL. State-of-the-art processes are the hallmark of Pacific Vial EPA glass vial