Changes in pressure can be a problem for bottled products. Have you ever seen at the store a bottle that is either bloated or sucked in (paneled)? This is caused by a difference in pressure between the inside of the bottle and the outside environment. While the contents of the product inside the bottle could be fine, a customer may perceive the product is expired or defective. This could have a negative impact on your sales. One of the best ways to alleviate this problem is to allow air to circulate while at the same time, restricting product leakage. And this is what vented liners do.
How do Vented Liners Work? - Vented liners allow a two-way passage of air through the closure and liner in order to equalize pressure between the inside and outside of the bottle. Thereby eliminating paneling and bloating caused by the product as it emits or absorbs oxygen and moisture. Essentially, vented liners allow your product to breathe while keeping your product from leaking out.
This is done via four specially designed parts. A liner, a membrane, a backer, and sometimes, an opening in the top of the closure.
Liner – Is the first line of protection for your product. And can be made of anything from foam to chemically treated paper. Some have a specific vent pierced through the material, while others use the porosity of the liner material itself to allow the container to breathe.
Membrane – The membrane is a separate layer within the vented liner that allows specified gases (such as oxygen and co2) to pass through itself while blocking the passage of other gases materials. Most membranes are generally hydrophobic (water repellant). And are ideal for all liquids with a similar surface tension as water. But they can also be designed to be oleophobic (oil repellant) for products with a lower surface tension. Another customizable feature of the membrane are the microscopic hole or “pore” sizes within the membrane itself. These pore sizes are measured by the micron. (1 micron = 0.001 millimeters). Membrane pore size is determined by the needs of your specific product.
Backer – Is a rigid material that is bonded to the membrane. Usually more porous than the membrane to allow for maximum airflow. The backer helps maintain the structure of the liner.
Opening, or Valve – Is literally an opening pierced into the top of the closure. Sometimes with an additional, elastic valve to aid in the venting process. Typically, this hole is not needed. But in some cases, is an important part of a customized vented closure system.
When To Use Vented Liners - When seeking a vented liner to equalize pressure in your packaged products. It’s important to understand the initial cause of the pressure inequality. Is it caused by...
Chemical Reaction - gases or moisture being emitted or absorbed by the packaged product.
Temperature – expansion or contraction of contents of a packaged container due to temperature.
Environment – expansion/contraction of contents due to altitude variations. (Traveling in a aircraft, or being delivered to a different sea level than the original level at packaging)
It's also important to consider the product itself. Is your product a liquid? Is it acidic? Does it contain caustic, or aggressive ingredients? Is it oil-based? Can it ferment?
Answering these questions FIRST, will make customizing a vented liner design for your packaging system a relatively simple task. Once you have decided that you would like to use vented liners. We will request an ingredients list or your SDS documents. This will help us determine the best vented liner.
Our Suggestions and Advice - Depending on the type of vented liner you choose. We suggest that you do the following:
When filling the container, make sure to leave 5-10% of empty head-space. This allows the gas to accumulate and escape out the vent without plugging, or clogging.
Perform a ‘tip test’. By tilting the container over and inspecting the outside of the closure and bottle neck for leaks.
Store, and transport your vented products with the containers in an UPRIGHT position.
Remember, that Vented Liners, in fact ALL liners, are designed for SINGLE USE ONLY.
Test Your Products and Packaging - We strongly advise that you perform tests with your product, container, and closures with vented liners for compatibility BEFORE you place any orders.
Have more questions? - If you would like more information. Or would like some assistance in ordering the correct vented liner to fit your needs, give us a call! Our support team is standing by during regular business hours to help. Please contact our customer service team
