A typical 8 oz disposable air horn will last about 90 seconds at best depending on how long it has been stored and slowly leaking and losing propellant over time, and there is a catch. Using it continuously will cause it to freeze-up, especially in cold weather, within about 10 seconds. When this happens the sound will diminish greatly, and it may stop producing sound completely until it warms up again. It could take a few minutes to be usable in warm weather, and it may not warm up at all in cold weather.
In addition, as the contents of the can empty, the sound volume will also diminish significantly, so it is common for them to be discarded well before they are empty.
By comparison, the WoodsCan Hornet rechargeable electric air horn will reliably run continuously at 121 decibels for 35 minutes before the battery runs down on a single charge. A Hornet rechargeable air horn can be recharged 500 times.
