I have been playing with the MQ2 Smoke, LPG, Carbon Monixide gas sensor for Arduino and electronics projects. I have found this little sensor to work quite well as an indicator for gas/smoke levels but the accuracy of the PPM values is a bit questionable. I expect some calibration could improve the accuracy and reliability greatly.
I made some quick code which adapts the existing code I found online with my basic Nokia 5110 LCD display code for use with any Arduino. This could be quite handy for a home automation project and enable a person to have remote monitoring for danger.
I think for my project I will utilize an existing commercial smoke detector which triggers a micro controller input, but I do have another project in mind where the MQ-2 sensor may be of great benefit. Video on that soon.
Here is the link to my Arduino code:
http://mkme.org/forum/viewtopic.php?f=2&t=656
Here is the full video on the sensor: