ASTM D3481Standard Test Method for Manual Shelling Two-Piece Child-Resistant Closures That Are Activated by Two Simultaneous Dissimilar Motions
This test method covers the measurement of the force required to separate (or “shell”) the snap-fitted outer cap from the inner cap of Type IA, IB, or IC child-resistant closures. This method does not measure the force required to separate parts of a child-resistant closure system that were originally “screwed-on” instead of “snapped-on” (for example, pull a cap over or through continuous or multi-start threads when the cap was originally screwed on). Method is to pry (lever) the outer element from the inner, measuring torque applied. D7257 is the newer machine standard.
Before conducting ASTM D3481, it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.