What the Libra zodiac sign is all about: Libra is the seventh of the 12 zodiac signs, which begins its cycle in early fall every year during Libra seasonâwhich falls around September 23-October 22.
How it works. This schematic shows the component parts of a typical leak-down tester. The gauge on the right is held at a standard pressure by adjusting the pressure regulator while the gauge on the left shows an example reading of 85-or 15% leakage.
Duct BlasterÂ®. 1  A Duct Blaster is used to directly pressure test the duct system for air leaks, much the same way a plumber pressure tests water pipes for leaks. 2  The Duct Blaster fan is first connected to the duct system at the air handler cabinet, or a return grille. After temporarily sealing all remaining registers and grills, the Duct Blaster fan is turned on to force air through all.