Measuring Ranges Resolution 0 - 10,000 ppm (Semiconductor Sensor) 0 - 100% LEL (Catalytic Sensor) 0 - 100% Volume Gas (Thermal Conductivity Sensor) ppm : 0 - 499ppm ppm : 500 -10000ppm LEL : 0 - 10% LEL : 10 - 100% Vol Gas : 0 - 100% 1ppm 10ppm 0.1% ...