Arcoplast recently set out to determine the pressure loss possible when their fiberglass composite panels are secured using screws instead of an adhesive bond. They provided Technical Safety Services, Inc. with four 24”x24” 6mm cement core panels. A single, #12 stainless steel, pan-head, self-tapping screw was inserted into the center of each panel.
The four screws and holes each used a different sealing method. Panel 1 received no such sealing, Panel 2 was sealed with Dow/Corning Type 999A Glazing sealant (a premium construction-grade sealant), Panel 3 was sealed with Arcoplast’s exclusive finishing compound, and Panel 4 saw the same sealing, but also had the bracket sealed with Arcoplast finishing compound.
Even before the tests were completed, it is a safe guess as to which method would perform the best. But the difference between an unsealed screw, and the best sealed option performed almost seven times better, and was over 12 times lower than the maximum allowable leakage. The screw and bracket sealed with Arocplast finishing compound (Panel 4) saw a miniscule 0.92 Pa/min loss at 0.000065 scfm.
Panel 3 tested out at a paltry 1.69 Pa/min at 0.00099 scfm, the Dow/Corning sealed screw and hole (Panel 2) finished with 3.29 Pa/min at 0.000182, which was 50% better than the unsealed (Panel 1) 6.76 Pa/min loss at 0.000374 scfm.
The Public Health Agency of Canada document, Laboratory Biosafety Guidelines: 3rd Edition (2004), requires that a Containment Level 4 room exhibit a maximum of 12.5 Pascal (Pa) per minute pressure drop at 500 Pa over a 20-minute period. Given the dimensions of the test enclosure, the maximum rate of allowable air leakage at 1,000 Pa was calculated to be 0.0056 standard cubic feet per minute (scfm).