When a detector is first powered on, it takes some time for the sensor reading to stabilize. The detector may read high values in the beginning during the warm-up period. This is especially so for metal-oxide and electrochemical sensors, for which we recommend keeping them powered on for at least 2 hours (even 24 hours in the ideal case) to let the reading stabilize. For optical sensors and pellistors, the reading stabilizes in approximately 15 minutes.