The term “vial” is somewhat undefined and is usually described as a small, cylindrical, and flat-bottomed containers used to hold liquids. Most sample vials are made of plastic or glass, and include a separate or attached lid or closure. Sample vials are categorized by material and also by their size or specific purpose.
- Glass sample vials are categorized by the type of glass used to make them.
- Type I, Class A glass sample vials are made from low-expansion borosilicate glass
- Type I, Class B glass sample vials are made from an alumino-borosilicate glass
- Type II are made from soda-lime glass
- Plastic sample vials may be made from a variety of resins, including:
- Low-density polyethylene (LDPE)
- High-density polyethylene (HDPE)
Glass sample vials may be clear or amber-colored (to protect the contents from ultraviolet light). Plastic sample vials are available in a range of colors, including amber, natural, and clear resins.
Types of Closures
Sample vials may have different types of closures, depending on their use and the material being stored.
- Screw caps
- For both glass and plastic sample vials
- May be closed or open
- Typically made from polypropylene or phenolic resin (with a variety of closure liners, including PE foam, PTFE, cork, tin, etc.)
- Caps for plastic sample vials may be attached by a tether to the vial itself
- Also called “captive” closures
- Snap caps (external): Both glass and plastic sample vials
- Plug caps (internal): Both glass and plastic sample vials