Child-resistant caps: holding off the child without locking out the adult
A child-resistant cap is not just a cap that is harder to open. It is a measured compromise: hold out against a four-year-old, and remain usable by a seventy-year-old. An international standard says how to check it.
By Tecmom editorial team · 2 min read
A contradictory specification
A child-resistant closure meets two opposite requirements. It must stop a young child from reaching the contents, and remain manageable by an adult, including an older one, who opens and closes their treatment several times a day. A cap that is simply screwed on tight would fail the second test.
The solution lies in a movement a child cannot yet coordinate. The most common combines two actions: push and turn. Without pressure, the outer shell spins freely on the inner shell; with pressure, lugs engage and the cap unscrews.
How ISO 8317 tests it
The reference standard is ISO 8317:2015, which sets the requirements and test methods for reclosable child-resistant packages. Its tests are run with people, not machines. According to descriptions published in the trade press:
- a panel of children aged 42 to 51 months has five minutes; the pack counts as child-resistant if no more than 15% open it in that time, and no more than 20% over the whole test, demonstration included;
- a panel of adults aged 50 to 70 must be able to open and properly reclose it, at least 90% of them.
The standard qualifies a pack design, together with the container it closes. The consistency of each lot is a matter for Good Manufacturing Practice.
Where it is mandatory
In the United States, the 1970 Poison Prevention Packaging Act requires child-resistant packaging for most oral prescription drugs, with exemptions listed in federal regulations. In the European Union, the CLP Regulation requires it for certain hazardous chemicals sold to the public, referring to ISO 8317 for reclosable packs. For a medicine, its file sets the closure.
Why it all happens in the mould
A child-resistant cap is an injection-moulded part, often in two shells. The lugs, the thread and the springiness that brings the outer shell back come out of the mould finished, with no rework. Their function rests on tiny engagements: tooling precision is the function itself.
That is also why the cap never works alone: it engages a neck finish, and it is the pair that gets qualified. Tecmom designs and builds its moulds in-house. See our expertise.
In the Tecmom range
The catalogue offers a child-resistant cap with a 28 mm neck finish, and lists a 125 ml wide-neck HDPE bottle as compatible with a child-resistant cap. See pharmaceutical packaging.
A good child-resistant cap goes unnoticed: the child fails, the adult opens. Behind that simplicity lie two test panels, a regulatory file and a mould in which every lug was decided before the first shot.
Glossary
- Child-resistant
- Said of a pack that is hard for a young child to open and usable by an adult.
- ISO 8317
- The international standard for reclosable child-resistant packages.
- Double shell
- A cap made of two nested parts that only engage under pressure.
- Injection moulding
- A process that forces molten plastic into a closed mould; fine details come out finished.