Safe-use times for chemical suits

This can easily be shown graphically. The Permasure Toxicity Risk Calculator calculates time to reach the chemical toxicity limit for chemicals at temperatures between -10^oC and 50^oC. As an example, the graphs shown indicate the effect of temperature on both permeation rate and calculated safe use time for Dichloromethane against a ChemMax 3 coverall.

Graph 1 shows the effect of temperature on permeation rate, indicating it increases from - 0.2 µg/min/cm² at 15^oC, to - 1.7 µg/min/cm² at 45^oC.

Graph 2 shows the effect on the “Safe-Use Time”, i.e. the time it takes to reach the toxicity threshold for the chemical, based for dichloromethane on a toxicity threshold of 20 µg/min/cm².

Safe-Use Time reduces from over 100 minutes at 15^oC to less than 20 minutes at 45^oC.

This example illustrates two important points:-

• The fact that permeation tests are conducted at 23^oC is ONE reason why they cannot be used to indicate whether or how long a chemical suit will provide protection in a given situation. Unless the application temperature is at the same temperature as the test, the results of the test are meaningless.
• The analysis above has been made using the free Permasure Toxicity Calculation tool available for Lakeland’s ChemMax 3, ChemMax 4 and Interceptor coveralls. It shows how Permasure can contribute key information to a risk assessment for a chemical protection application. Permasure can be used as a tool to more effectively manage safety in real world applications by indicating safe-use times at varying temperatures, thus enabling safety managers to manage tasks in order to improve protection for workers using hazardous chemical suits.