Significance and Use

There are numerous flammability ratings and tests. Almost without fail, these standards and tests are focused on very specific industries or results, many of which are not applicable to the membrane switch/human machine interface assembly. This test is designed to provide relative results between membrane switches that have been assembled to the unit's final enclosure, housing, etc.

In addition to the test's measurement of the rate of burn, a laboratory can also observe the effects of burning material falling from the test specimen onto other materials (typically a gauze test area) not directly part of the test specimen. The indirect burning is an issue of interest to see if the test specimen will be able to act as an initiator for a far greater and more damaging flame event (fire). Observations should be noted, as qualitative descriptions, as appropriate.

This test can measure the flammability via the use of high-speed photographic or video equipment.

Temperature of the ignition source can be measured via a calibrated thermocouple pyrometer, calorimeter or IR thermometer with an appropriate range.

This test is not designed to provide a PASS or NO PASS status for a switch, rather, it is designed to provide a grade for the level of flammability of a membrane switch assembly (as defined in 3.1.10). The end user should make the final determination if the level of flammability is acceptable for the particular application.

1. Scope

1.1 This test method covers the determination of the flammability characteristics of a membrane switch.

1.2 This test method defines the MSB rating of a membrane switch. Each character of the MSB rating represents a discrete characteristic of a membrane switch performance under destructive thermal loading.

1.3 This test procedure will be destructive, but should provide an insight into the relative performance flame-resistance characteristics of differing designs or assemblies, or both.

1.4 This test method will focus on the use of convective contact (burner flame) method for ignition, though other methods of ignition are available.

1.5 This test method is designed to determine if the membrane switch assembly will add (or detract) from the flame propagation from an exterior flame/fire source.

1.6 If this test is intended to be used for an internal flammability source then set up the unit under test (UUT) appropriately and note it in the test scope and results.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Keywords

fire propagation apparatus; flame endurance; flame propagation; flame spread rate; flame target area; flame time; flame time of drippings; flammability; mass loss rate; membrane switch; time to ignition;

ICS Code

ICS Number Code 31.220.20 (Switches)

DOI: 10.1520/F2866-11

ASTM International is a member of CrossRef.

ASTM F2866