For how long will a protective suit resist hazardous chemicals? What clothes will handle a particular chemical successfully? That is what a FOI research project is about to determine.

Tens of thousands of hazardous chemicals are in daily use all over the world. It is economically infeasible to determine for how long time protective suits will resist that many substances. Therefore FOI is developing a predictive model based on the properties of the chemicals.

The project began with the compilation of a database comprising one thousand compounds, each described by 60 properties, e.g. molecule size, surface tension, boiling point and solubility in water. Eighteen chemicals were selected as a statistical sample representing different combinations of properties.

In the next stage, the scientists will measure how well the materials of three types of protective suits will resist the 18 compounds. Two suits are permeable, i.e. they “breathes”, and one is non-permeable. At each measurement, one compound will be applied onto the material surface. If it permeates the material, the measurements will determine how fast and to what extent. This research stage will be completed in the summer of 2010.

“Our measurements can establish connections between the properties of the compounds and their ability to penetrate different types of protective barriers. For instance, it will be possible to study what a high boiling point and high density will do in conjunction,” says Ingrid Sundholm, the FOI scientist in charge of the tests.

During the autumn, her team will make a model that predicts penetration times for a large number of chemicals. It will make it possible to estimate for how long a person with a certain type of protective suit will be able to work in a contaminated area. The intention is to support the Swedish Defence Forces when it serves on international or national missions.

In the future, it is possible that the model will be used in the development of chemical protective suits, where the materials are optimized to resist hazardous substances. The civilian sector, too, may benefit from the research.

”However, it requires further development of the model. The Rescue Services’ hazmat suits may be of denser materials, because they usually carry out shorter operations e.g. during an accident. Military personnel may have to wear hazmat protection for longer periods of time, so their suits must be more comfortable and ‘breathe’ to keep the body temperature at tolerable levels,” says Ingrid Sundholm.