If your smoke detector is beeping or chirping occasionally, it's trying to tell you something. Find new ones on Amazon:
USA: http://amzn.to/2ei4dOr
Canada: http://amzn.to/2ettE1m
UK: http://amzn.to/2dxjCv9

Either it needs a new battery, or it's at end of life and needs to be replaced.
Smoke alarm devices have a specific recommended life, often 10 years. If your detector has reached the recommended limit, it's time to replace all in your house.

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