Cap Sizes and
Neck Finishes
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Plastic Closures
There are two basic types of plastic closures used for
scientific applications: thermoset and thermoplastic.
Thermoset closures cannot be remelted after they are formed. They
provide the widest range of chemical compatibility and they exhibit the most
tolerance to temperature of all plastic closures. Because thermoset closures
are rigid, they provide the most consistent adherence to close dimensional
tolerances. Common resins include urea, phenolic, and melamine.
Thermoplastic closures can be remelted after they are formed.
They are known for good impact strength, cost effectiveness, and pliability.
Common resins include polypropylene (autoclavable) and polyethylene.
Metal Closures
Metal closures offer the widest range of temperature tolerances and are very
resistant to fracture from impact. A metal closure is manufactured from
either steel (coated with anti-corrosive coating of either chromeplate or
tinplate) or aluminum.
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Closure Size Info
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Screw thread closure sizes are expressed in two
numbers.
The first number refers to the closure diameter (in mm) and the second
number represents the GPI finish (the top of the container).
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For example, a neck size
of 28-430 has a diameter of 28 mm and fits a container with a 430 GPI
thread finish.
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Selected
Heights of Standard Closures
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Closure Size
(mm)
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400 Finish
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410 Finish
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415 Finish
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425 Finish
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8
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-
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-
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-
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.262-.280 in
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10
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-
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-
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-
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.273-.291 in
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13
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-
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-
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.428-.458 in
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.298-.316 in
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15
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-
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-
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.533-.563 in
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.298-.316 in
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18
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.359-.377 in
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.499-.529 in
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.593-.623 in
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-
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20
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.359-.377 in
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.530-.560 in
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.718-.748 in
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-
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22
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.359-.377 in
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-
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.813-.843 in
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-
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24
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.388-.406 in
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.622-.652 in
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.933-.963 in
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-
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28
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.388-.406 in
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.684-.714 in
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1.058-1.088 in
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-
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33
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.388-.406 in
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-
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.245-1.275 in
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-
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38
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.388-.406 in
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-
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-
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-
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43
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.388-.406 in
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-
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-
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-
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45
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.388-.406 in
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-
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-
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-
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48
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.388-.406 in
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-
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-
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-
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53
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.388-.406 in
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-
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-
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58
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.388-.406 in
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-
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-
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-
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63
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.388-.406 in
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-
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-
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-
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70
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.388-.406 in
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-
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-
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-
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77
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.467-.485 in
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-
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-
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-
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83
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.467-.485 in
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-
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-
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-
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89
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.515-.533 in
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-
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-
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-
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100
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.577-.595 in
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-
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-
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-
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110
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.577-.595 in
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-
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120
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.665-.683
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