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Manually shelling two-piece Child-Resistant closures


Test Summary


 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.  The method is to pry (lever) the outer element from the inner, measuring torque applied.


Test apparatus


A calibrated torque meter capable of indicating clockwise and counter-clockwise torque.  Special fixture as described in the ASTM  standard.




Select sufficient quantities of closures to be in accordance with established statistical sampling procedures. l If required the closures can be conditioned in environments as specified in the ASTM standard. 



1. Apply all closures to be tested to the appropriate containers at a specified and uniform torque using the Tornado
2. With the specified special fixture fitted to the Tornado, secure the closure, and grasping the container at its base, apply torque by hand to “shell” the two parts of the Child-Resistant closure.
3. Apply torque at a slow and steady rate that allows the total testing time to range between 15 and 30 seconds for each closure.
4. The end point of the test should be the lifting of the outer cap to a position where the plane of the top surface of the outer cap forms a 45° angle with the bottom plane of the bottle.
5. Record the maximum torque for each sample. Tornado can display the peak torque digitally. A printer may be used to provide a hard-copy.
6. Record all details of the samples including batch numbers, laboratory environmental conditions and details of the test equipment

Mecmesin Test Equipment Required for ASTM D3481

Tornado digital torque tester



ASTM D3481 Standard Test Method for Manual Shelling Two-Piece Child-Resistant Closures That Are Activated by Two Simultaneous Dissimilar Motions

Set application torque with Tornado

ASTM D3481 manual shelling child resistant closures

Child-resistant closures

ASTM D3481 manual shelling child resistant closures

ASTM D3481 testing with Tornado

ASTM D3481 manual shelling child resistant closures

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