The Invisible Problems in Mastics, Gaskets, Valves & Seals

Water vapour doesn”t just sneak around the edge of seals to get into places it shouldn”t be, it actually permeates through the fabric of the seals, mastics gaskets or valves themselves, sometimes in large volumes. Many materials are a good barrier against liquids, but when it comes to vapours, which are usually invisible, they are often very poor barriers indeed.

Versaperm”s range of vapour permeability measurement equipment is ideal for both development and QC as it allows you to test and develop a product design to determine the effect of both the manufacturing techniques and the materials used. Manufacturing alone can decrease a product”s barrier properties by a factor of four.

The system is fast, and offers a simple and accurate way to measure vapour permeability not just for water vapour but also for hydrocarbon vapour and most other gasses including hydrogen, oxygen, solvents and CO2.

Results are accurate in the parts per million range for most materials and enclosures and you can characterise several separate material samples, seals or enclosures at one time, sometimes in as little as 30 minutes. Conventional gravimetric measurements take several days, weeks or months and are significantly less accurate.

Several commonly used materials, such as cellulose, EVOH or PVOH, actually allow water vapour to flow through them almost as if they weren”t there. Some plastics permit hundreds of times more vapours to flow through than others. This leads to gaskets and seals that don”t actually seal properly for some vapours.

As well as manufacturing the instruments, Versaperm offers a permeability laboratory service for companies that need to test samples on an irregular basis.