Stoppers
Stoppers, also known as bungs, are used to give an airtight seal to laboratory flasks and test tubes by fitting tightly inside the neck of the container and preventing material from spilling. Stoppers can be made of glass, cork, rubber, or silicone. They are typically designed with a conical shape, but straight, flanged, and tapered options are also available.
Stoppers are the preferred choice for many applications requiring a tighter seal or a greater degree of chemical resistance. They also provide a good seal when a solution needs to be shaken or mixed without spilling. Stoppers are generally cylindrical in shape and have a tapered bottom end. They may be marked with a stopper number or size on the top and bottom diameters of the stopper. Sizing can vary among manufacturers.
Stoppers are available in a solid design or with holes known as positions placed in the top. Positions allow easy access to the material contained in the sealed vessel by pipettes, tubing, or other equipment without full removal of the stopper.
What Types of Stoppers Are Available?
• Turnover stoppers have external serrations to create an excellent internal seal combined with a flexible turnover sleeve that folds down over the container’s neck to create a double seal
• Serum bottle or vial stoppers have two or three legs with external serrations or straight sides and a flanged top to create an airtight seal
• Straight bromobutyl plug-type stoppers provide a maximum seal for vials and serum bottles with a straight-wall glass finish
• Ultra-pure, straight bromobutyl plug-type stoppers provide high chemical purity and low gas permeability. They offer excellent performance during freeze drying processes such as lyophilization, where stoppers must remain stable during transfer and sublimination phases
• Silicone recessed septa stoppers are non-toxic and have external serrations to create an effective internal seal
Chemglass Life Sciences Rubber Stopper, #5-1/2, One Hole, Black
Rubber Stopper, #5-1/2, One Hole, Black. These stoppers are suitable for practically all general laboratory uses. Composition ensures resiliency and pliability over a long period and withstands laboratory conditions without hardening. The dimensions are in accordance with specifications established by the N.B.S. and are low in free sulfur (1/2%). Autoclavable at 250F for 30 minutes under water or steam conditions only (not dry heat). End user must test for their specific application. Diameter: Top (28mm), Bottom (24mm). Length: (25mm). Diameter of hole: (5mm).
Electron Microscopy Sciences Vacule Red Stoppers
Heavy wall construction, designed for lyophilization and freeze-drying. Manufactured from Wheaton 33 low extractable borosilicate glass (meets ASTM Type I Class and USP Type I Standards). Accessory for 5 and 10 ml Vacule Vials.
Chemglass Life Sciences Rubber Stopper, #11-1/2, Two Holes, Black
Rubber Stopper, #11-1/2, Two Holes, Black. Similar to CG-3026 and CG-3027 except with two holes. These stoppers are suitable for practically all general laboratory uses. Composition ensures resiliency and pliability over a long period and withstands laboratory conditions without hardening. The dimensions are in accordance with specifications established by the N.B.S. and are low in free sulfur (1/2%). Autoclavable at 250F for 30 minutes under water or steam conditions only (not dry heat). End user must test for their specific application. Diameter: Top (63mm), Bottom (50mm). Length: (25mm). Diameter of holes: (5mm).