smoke and PIR detectors

Photoelectric smoke detectors actively transmit/receive tiny pulses of ~800-900 nanometer infrared to sense the scattering/occlusion effects of smoke particles.

PIR motion detectors passively sense/receive the 5-15 micrometers infrared radiated from a warmer than ambient human body.

The two technologies do not interact with each other.

what about the microwave motion sensor? does it interact with any of the photoelectric or ionization smoke detectors?

Cheers..

Normally, microwave Doppler motion sensors do NOT interact with PIR or smoke sensors.

However, PIR and smoke sensors typically use sensitive high-gain amplifiers which MAY be disturbed by microwave radiation IF those amplifiers are not properly shielded from EMI.

Hi again,

Can anyone tell me if there is any fire detector that surely does not interact with a microwave based sensor?

Many thanks..

Cheers

Most commercial grade smoke sensors have to pass a thorough EMI/RFI test to verify that they do not malfunction when exposed to electrical transients and RF interference. The power radiated from microwave motion sensors is VERY SMALL, so interaction is highly unlikely.

There are limits to the frequencies and field levels tested. If you exceed these limits, unpredictable operation can occur. Interference could possibly occur if a microwave sensor is improperly mounted within a couple centimeters of a smoke sensor. A cell phone tower within a few meters of a smoke sensor could also cause problems.

If you have a high EMI installation, your best option is to research available sensor specifications, pick the best ones you can afford to buy, and actually test them on site. Best wishes.

You would also do well to consult with the manufacturer with regards to application of these devices. I worked in an organisation that designed and manufactures smoke detectors. There are strict standards that these devices have to conform to before they can be sold. I am not sure about domestice smoke detectors, though.