Do you have to recharge a fire extinguisher every year even if if still shows some charge? Is the year the standard or does it depend on whether the extinguisher is showing no charge? What if it still shows a charge but it is not fully charged?
In other words does one go by what the extinguisher shows or by the arbitrary year?
It is normal in commercial establishments to have them "formally" inspected/tagged once a year. Generally someone is supposed to make periodic checks that they are still indicating a happy gauge reading more often than that.
If the gauge is not in "the green" then the extinguisher should be recharged immediately (if it is in fact one that can be - many "home" models cannot - those should just be replaced.)
So long as the gauge is in the green, "service" is not required until the tank is due for a hydrostatic test (once every 5 years) which requires emptying it, testing it, and then refilling it. I don't think this really applies to home "disposable" extinguishers, but it does apply to refillable models.
If you happen to have a CO2 type extinguisher, there is not a guage - you just need to weigh it periodically to verify that the charge is still present. The "tare weight" (empty weight) should be stamped on the cylinder, and the CO2 is whatever weight over the tare weight is registered on the scale.
First of all, not all fire extinguishers are capable of being recharged. The extinguisher should have an info label describing maintenance procedures, e.g. that it needs to be tested or recharged every 5 years (or 12 years, or whatever it says), or that it must be disposed of 12 years after the manufacture date.
You should also have it tested (or replaced) if:
Based on the wording of the question it sounds like your fire extinguisher should be tested or replaced. Other than a cursory visual inspection there's not really any way for you to evaluate whether the fire extinguisher is capable of performing when needed, which is why you need to adhere to the maintenance schedule. It is a safety device, after all, and won't do you much good if it's dead.
