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
Synthware™ Flask Length PFTE Stopper
Stopper features a PTFE handle for easy gripping.
Synthware™ Threaded Sleeve Type Septum
Threaded Sleeve Type Septum made from natural white rubber.
Synthware™ Pluro Stopper Set
Pluro Stopper Set comes with 8 sizes.
Synthware™ Spherical Penny Head Stopper
35/20 Ball Joint Penny Head Stopper
Bel-Art™ Extracting-Nut Safe-Lab™ Stoppers
PTFE-resin stoppers with red polypropylene extractor nuts require no lubricants
Plasticoid One-hole Rubber Stoppers for Kjeldahl Flasks
Light tan rubber stoppers
Plasticoid One-hole Rubber Stoppers for 800mL Kjeldahl Flasks
Light tan rubber stoppers
Plasticoid Solid Rubber Stoppers for 800mL Kjeldahl Flasks
Light tan rubber stoppers
Eisco™ Solid ASTM Neoprene Stoppers
Pack of ten solid ASTM neoprene stoppers. Made from long lasting neoprene rubber. Oil resistant, use up to 250°F / 120°C. Suitable for use with petroleum products, minerals, oils, fats as well as most inorganic acids.
Eisco™ Polypropylene Flat Head Stoppers, Multipack
Acid-proof, autoclavable, and come in a variety of joint sizes
Eisco™ Rubber Cones
Designed for use with Buchner Funnels in filtration assemblies, these cones are made of flexible, quality neoprene rubber. Rubber Cones have superior chemical stability, and can withstand a wide temperature range.
United Scientific™ Rubber Stoppers, One Hole
Ideal for use with non-aggressive or concentrated solutions. Rubber Stoppers withstand temperatures from -13°F to +158°F (-25°C to +70°C).