Patent ID: 8395778

Claim:
A soot number determining device, comprising: an intake line for intake of a gas potentially containing soot through a filter paper introduced into the intake line; a conveyor device that conveys a soot spot created on the filter paper by intake of the gas at an intake position into an analysis position; and a device for measuring the degree of blackening of the filter paper caused by the soot spot, wherein the device includes at least one of: (i) a reflex optocoupler having a light source and a photodetector, the soot spot being conveyed into the analysis position in front of a setpoint position, the filter paper then being conveyed further in increments until the soot spots lies after the setpoint position, wherein the reflex optocoupler records measurements of an intensity value of reflected light from the soot spot, and the soot number being determined from a minimum of a measurement series on which the measurements are performed; or (ii) a soot image reference scale having a plurality of soot image reference areas, each of which has a predefined gray value and an opening, wherein each opening of the soot image reference scale is positionable with respect to the soot spot of into the analysis position so that the soot spot is visible through the opening, the soot image reference scale being coupled to a position transmitter for determining a position with respect to the analysis position.