What do these have in common?

ISO 8317

They are all injection molded screw caps, yes...

They are all child proof or are they?

All closing mechanisms that have been tested according to ISO 8317 have over the years gained word of mouth for being child-resistant after being tested by both children (3 years and 6 months to 4 years and 3 months) and the elderly (50 years to 70 years).

The challenge here obviously lies in more than the fact that it should not be opened by children. It must also be able to be opened by the consumer. Common to all closing mechanisms that have been tested according to ISO 8317 is that none of them has been exposed to the chemical or substance that it will later help protect our children against.

This is an ever so small miss. 

We know that influence from the contents can cause, for example, the inner part of the cap to swell and come into direct contact with the outer part of the cap. This means that the child-resistant function no longer works as intended. At the same time, such an influence could also cause the cap to fit loosely on the jerrican/bottle.

Definitely not good.

What can we do about this?

We have ISO 16101, which describes the chemical compatibility of plastics.

Do we have an ISO/CEN standard that describes the mechanical measurement of closing mechanisms before and after ISO 16101?

Tightening and loosening torque?

There is a lot of work on "easy opening" during the day, should this be part of the problem?