This part of ISO 4524 provides procedures for conducting mixed flowing gas (MFG) environmental tests involving exposures to controlled quantities of corrosive gas mixtures.

It describes the required equipment and the methods for gas, temperature and humidity control that enable tests to be conducted in a reproducible manner. Reproducibility is measured through the use of control coupons the corrosion films of which are evaluated by mass gain, coulometry or by various electron and X-ray beam analysis techniques. Reproducibility can also be measured by in situ corrosion rate monitors using electrical resistance or mass frequency change methods.

MFG tests can be used to:

• evaluate novel electrical contact metallization for susceptibility to degradation due to environmental exposure to the test corrosive gases;
• evaluate the shielding capability of connector housings that may act as a barrier to the ingress of corrosive gases;
• evaluate the susceptibility of other connector materials such as plastic housings to degradation from the test corrosive gases.

MFG tests are not normally:

• used as porosity tests (for guidance on porosity testing, see ISO 10308, Metallic coatings — review of porosity tests);
• applicable where the failure mechanism is other than pollutant gas corrosion such as in tin-coated separable contacts.