Snap-Fit Closures

A snap-fit, or snap-on, closure is made of a resilient material and is designed to deform as it passes over a protruding feature on the container (Fig. 11.7). Removal of the closure requires deformation again to snap the closure back over the protruding feature, which is typically a retaining ring. When the closure is in place, some resilient part of the closure system that is in contact with the container remains deformed, and provides a seal as it attempts to return to its original dimen- 

One of the major advantages of snap-fit closures is that they can be applied very quickly. A disadvantage is that they cannot be used for containers with internal pressures exceeding one atmosphere, since the pressure may act to snap the closure back off of the container. 

Snap-fit closure (reprinted with permission from [1]) 

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