The Role of Vents in Caps and Closures

To the untrained observer, a good seal is an airtight one. Not a single granule or molecule escapes the confinement of its container. However, that's not always the case.

Venting performance is a significant part of safe packaging.

Venting a package can relieve overpressure caused by the gassing of the filling product (e.g. hydrogen peroxide). Venting can also relieve under pressure caused by the cooling down of a drum after hot filling (e.g.: high-viscosity liquids). Venting technology helps prevent unsafe stacking conditions of lightweight packages as a result of pressure changes caused by temperature variations.

Venting technology also aids in the prevention of package distortion and other physical changes that can occur during the distribution cycle. It can also reduce the risk of package leakage due to pressure changes. This technology is especially beneficial for products that require protection from oxygen or other gasses that can cause damage to the product (e.g.: foods and beverages). Additionally, venting technology can help maintain package integrity and the shelf life of products by preventing the growth of microorganisms and ensuring product quality.

Container Venting Tech Talk

Valve Type Vents

Standard valve-type vents are made of high-performance rubber. The functional operation of this type of vent is based on pre-tensioning the stem of the vent and allowing re-closing after, over or under-pressure has occurred. Rubber mushroom and umbrella vents are available for Tri-Sure® plastic and steel plugs in many executions.

Membrane Type Vents

The standard microporous membranes (MPV) type vent consists of a P.T.F.E. (Teflon) backing and is available in G¾ Tri-Sure plastic plug execution provided with a protective bulb. This in turn, can be assembled into a Tri-Sure combination plug or a Tri-Sure vented Screwcap. For special applications, insert-type vents are also available. By nature, the membrane is liquid-repellent and allow the container to breathe while preventing the ingress of moisture or foreign matter.

Closure venting performance

The performance of a vent system depends on its location above the liquid surface. It can not be affected by the contents of the drum or any other foreign material that can block the outlet vent opening.

Cautionary notes

  • Only vented Tri-Sure® Tab-Seal® are allowed on vented closures.
  • Always store upright.
  • Store under cover.
  • Air transport is not permitted.
  • Check National Regulations for local requirements.


It remains the responsibility of the user to check if all requirements in the law and regulations are met e.g. product filling, safety, and transportation. Chemical compatibility testing should only occur under laboratory conditions and in actual use of the vent-closure system.

R Plug mushroom venting

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