Do not test a fire extinguisher by discharging it at all. If you do discharge any amount of product to test your First Alert® fire extinguisher, your warranty will be void. This is not the recommended way to check your fire extinguisher. If any amount is discharged, the unit should be replaced. The recommended way to test fire extinguishers with the pressure pin on top is to press in the pin. If it pops back up, your extinguisher is still pressurized. On models with a pressure gauge, if the needle is in the green, the unit is pressurized.