Home fires are often unpredictable, and they can be deadly. That's why you need one full-floor, multipurpose fire extinguisher on each level of your home and one in your garage, plus smaller, supplemental units for the kitchen and car.

Heavier extinguishers have more flame retardant and delivered it quicker and longer in our tests. Though models that weighed more than 9 pounds can be harder to hold and use, you should still buy the largest one you can comfortably handle.

No matter which fire extinguisher you buy, make sure its pressure indicator shows "full" and that it was manufactured within the last year. The National Fire Protection Association recommends that dry chemical extinguishers that are intended to be discarded after use should be disposed of 12 years after the date of manufacture. It would be useful if more manufacturers placed an expiration date on their extinguishers.

We tested two aerosol fire sprays, the First Alert AF400 Tundra and the Shield Fire Protection Kitchen Guard, and have judged each as Don't Buy: Performance Problem. We also found a third brand, Knockout 360, advertised as an aerosol fire spray. Unlike the extinguishers we tested, none of the sprays has a pressure indicator that shows whether the unit is ready for use. And the sprays are not intended to replace a standard extinguisher (NFPA 10 compliant) where required, as the makers say on the labels. The sprays sometimes made the grease fire in our tests flare up before they put it out. That could cause the fire to spread or prompt the user to stop the spray. We found that two of the 10 Tundra samples didn't properly discharge.