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.
How pregnancy tests work. Home pregnancy tests work in the same way, but some are designed to be more sensitive than others. Pregnancy tests work by measuring the level of hCG (human chorionic gonadotrophin) in your urine. The sensitivity of the test will be listed on the package and you can tell in two ways.