These centrifuge tubes are also useful for collecting and transporting biological specimens. Leakproof characteristics are ensured by a flat top plastic screw cap with an inner sealing lip. Tubes are made of translucent polypropylene or optically clear polystyrene with molded graduations from 2.5 to 50mL. Polypropylene tubes can be autoclaved and will resist temperatures up to 121°C; they will also resist acids, solvents and alkalies at room temperature. They withstand centrifugation speeds of 3000g. Polystyrene tubes can tolerate aqueous solutions of mild bases or weak acids, but not organic solvents, aromatic or chlorinated hydrocarbons, and they cannot be autoclaved. They withstand centriguation speeds up to 1000g.
The tubes are available in bags or in break-away polyfoam racks for better protection during transport, storage and for convenient laboratory use. Racks can hold up to 25 tubes; tube contents are visible from top to bottom since racks are provided with viewing slots. They are supplied sterile with green caps or non sterile with yellow caps.