A gas sensor is sensitive to concentrations between 2002200

A gas sensor is sensitive to concentrations between 200-2200 ppm and generates voltage output between 0-25 mV. The sensor has a repeatability error of 0.5%. If several readings are taken in an environment with an actual gas concentration of 750 ppm, most of the reading will be in what range?

Solution

Sensor Sensitivity range = 200 - 2200

voltage output range = 0 - 25 mV

and Repeatibility    = 0.5 %

Voltage output per ppm over 200 ppm = (2200 - 200)/25

                              = 80 ppm /mV

Actual Gass concentration = 750 ppm

voltage reading for this concentration = (750 - 200) /80

                                                                   = 550/80

                                                                   = 6.875 mV

On considering the repeatibility error of 0.5 %

The error for the Voltage reading will be = 6.875 * 5/1000

                                                                        = 0.03 mV

So the range of Voltage reading = (6.875 +0.034) and (6.875 - 0.034)

                                                           = 6.909 mV and 6.840 mV