Hi Arjiit,
You can check if the sensor is okay or not by just powering it up with 5V to the supply pin and have a current or resistance reading at the output pin. If you do have a current or resistance reading, then the sensor is fine.
Gas Sensor are tough and not easily damage by environmental condition. The perfect range for testing gas sensors is at room temperature which ranges from 20 to 25 degrees Celsius.
The sensing part of the Gas Sensor is based on the changes of resistance that varies with respect to the gas concentration. The greater the gas concentration will make the resistance inside the sensor lower or maybe higher depending on its characteristic or configuration of the sensor.
Calibration will put the Gas Sensor in correct operation. After you preheat the sensor, you need to set values(the analog reading to digital reading). If you do have an MCU, it will be easier. You will just code the values for analog to digital reading, otherwise you will use ADC devices for the readings and have some tutorials in the web about the system. (note: gas sensor produces analog reading and numbers for several type of displays are digital)
After having a digital reading, then try to calibrate the entire system correctly using some reference calibrated instrument or you can just have the standard values with respect to environmental condition.
For additional information, you can refer to this posted project.
http://www.eeweb.com/project/nikki_martinez/prototype-sensor-for-carbon-monoxidebest regards,
Neil
