Laboratory rubber stopper

A laboratory rubber stopper or a rubber bung or a rubber cork is mainly used in chemical laboratories in combination with flasks and test tube and also for fermentation in winery.[1][2][3] Generally, in a laboratory, the sizes of rubber stoppers can be varied up to approximately 16 sizes and each of it is specific to certain type of container. As the rubber stopper is used in many experiments, some specific experiment requires a specific material. For example, the M35 Green neoprene stopper is for chemical resistance. For food fermentation, M18 white natural gum is preferred. For high temperature application, red or white silicone rubber stoppers should be used.

(From left to right) One-hole Rubber bung size 10, Two-hole Rubber bung size 14, and Solid Rubber bung size 16

Sizes

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Rubber bungs can have one or more hole(s) for plugging in tubes depending on the specification of the procedures. To prevent the liquid chemical leaks or escape the container, the rubber bung should fit tightly to the container's opening; the dimension of the rubber bung is of concern. These are some of the sizes that are commonly seen in chemical laboratory.

(From left to right) Rubber bungs are aligned from size no. 1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 13, 14, 15, to 16, respectively. (Comparing to the ruler) Size No. Top
mm Bottom 000 12.7 8.2 12x75 test tubes 00 15 10 0 17 13 1 19 14 2 20 16 20x150 or 10ml test tubes 3 24 18 4 26 20 25x200(150) or 20ml test tubes 5 27 23 50 ml Flasks 6 32 26 250ml Erlenmeyer Flasks 7 37 30 500ml Erlenmeyer Flasks 8 41 33 1000ml Erlenmeyer Flasks/ Florence Flask/ Filter Flask 9 45 37 1000ml Erlenmeyer Flasks/ Florence Flask 10 50 42 1000ml Filter Flasks

2000ml Erlenmeyer Flasks/ Florence Flask

11 56 48 12 64 54 4000ml Filter Flasks 13 68 58 14 90 75 15 103 83 16 127 90

Additional images

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• Rubber bung size no.5 fits tightly on 50ml Pyrex® Flask

• Other equipments such as glass tubes can be plugged into the holes of the rubber stopper

See also

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References

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