Why is it important to control the relative humidity when testing SFRM?

Maintaining control over relative humidity during the testing of spray-applied fire-resistive materials (SFRM) is crucial because it directly impacts the accuracy of density measurements. In environments with high humidity, the moisture content in the air can affect the curing process and the density of the SFRM applied. If the density measurements are influenced by external moisture levels, it could lead to incorrect assessments of the material's effectiveness in providing adequate fire resistance.

Proper density is essential for ensuring that the SFRM will perform as intended under fire conditions. If the density deviates from expected values due to uncontrolled humidity, it could compromise the material's structural integrity, leading to failures in meeting safety standards and structural requirements during a fire event. Thus, controlling relative humidity is key to obtaining reliable test results and ensuring the SFRM’s performance meets specified fire protection criteria.