# US 2014/0196521 A1 · Detection of diesel exhaust fluid contamination > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196521 A1 - Document ID: US20140196521A1 - Status: Published application - Kind: A1 - Application number: 13/742,683 - Filed: 2013-01-16 - Published: 2014-07-17 - Earliest claimed: 2013-01-16 - Assignees: Caterpillar Inc. - Applicants: Caterpillar Inc. - Inventors: Amiyo Kumar BASU - Web page: https://patentgrep.com/patent/US20140196521A1 ## CPC - G01N 25/18: by investigating thermal conductivity (by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18) - G01N 33/2835: {Specific substances contained in the oils or fuels} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A method for detecting contamination in diesel exhaust fluid (DEF) used in a selective catalytic reduction process is disclosed. The method may include providing a plurality of temperature sensors arranged along a fluid column within a tank containing the DEF to be tested. The method may further include detecting a temperature of the fluid at each of the plurality of temperature sensors along the fluid column, determining temperature gradients along the fluid column from the temperatures detected by the plurality of temperature sensors, and comparing the temperature gradients along the fluid column with a set of reference temperature gradients. ## Claims ### Claim 1 A method of detecting contamination in Diesel Exhaust Fluid (DEF) contained within a tank including a plurality of temperature sensors arranged along a fluid column defined within the tank, the method comprising: detecting a temperature of the fluid at each of the plurality of temperature sensors along the fluid column; determining temperature gradients along the fluid column from the temperatures detected by the plurality of temperature sensors; and comparing the temperature gradients along the fluid column with a set of reference temperature gradients. ### Claim 2 (depends on 1) The method of claim 1, wherein the set of reference temperature gradients are retrieved from a look-up table or other dataset. ### Claim 3 (depends on 1) The method of claim 1, wherein the set of reference temperature gradients are determined by measuring temperatures along a similarly configured column of fluid in a tank containing DEF known to be of a desired composition. ### Claim 4 (depends on 1) The method of claim 1, wherein the plurality of temperature sensors are arranged along a vertical fluid column within a tank containing the DEF to be tested. ### Claim 5 (depends on 1) The method of claim 1, wherein the plurality of temperature sensors are arranged along a fluid column that includes fluids of different compositions within the tank containing DEF. ### Claim 6 (depends on 1) The method of claim 1, further including detecting changes in the temperature of the fluid at each of the plurality of temperature sensors along the fluid column as a function of time. ### Claim 7 (depends on 6) The method of claim 6, further including detecting the changes in the temperature of the fluid at each of the plurality of temperature sensors as the DEF in the tank undergoes a phase change. ### Claim 8 (depends on 7) The method of claim 7, wherein the detecting the changes in the temperature of the fluid occurs during a change in operational characteristics of a power supply having an exhaust aftertreatment system that uses the DEF. ### Claim 9 (depends on 8) The method of claim 8, wherein the phase change is occurring during starting of the power supply in ambient temperatures that are colder than normal operating temperatures for the power supply. ### Claim 10 An apparatus for detecting contamination in a tank of DEF containing reductant used in a selective catalytic reduction process, the apparatus comprising: a plurality of temperature sensors arranged along a fluid column within the tank, each of the temperature sensors configured to detect a temperature of the fluid at the position of each of the plurality of temperature sensors along the fluid column; and a controller configured to determine temperature gradients along the fluid column from the temperatures detected by the plurality of temperature sensors. ### Claim 11 (depends on 10) The apparatus of claim 10, wherein the controller is further configured to compare the temperature gradients along the fluid column with a set of reference temperature gradients. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein the controller is configured to retrieve the set of reference temperature gradients from a look-up table or other dataset. ### Claim 13 (depends on 11) The apparatus of claim 11, wherein the controller is configured to determine the set of reference temperature gradients from temperatures along a similarly configured column of fluid in a tank containing DEF known to be of a desired composition. ### Claim 14 (depends on 10) The apparatus of claim 10, wherein the plurality of temperature sensors are arranged along a vertical fluid column within a tank containing the DEF to be tested. ### Claim 15 (depends on 10) The apparatus of claim 10, wherein the plurality of temperature sensors are arranged along a fluid column that includes fluids of different compositions within the tank containing DEF. ### Claim 16 (depends on 10) The apparatus of claim 10, wherein the controller is further configured to detect changes in the temperature of the fluid at each of the plurality of temperature sensors along the fluid column as a function of time. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the controller is further configured to detect the changes in the temperature of the fluid at each of the plurality of temperature sensors as the DEF in the tank undergoes a phase change. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the controller is configured to detect the changes in the temperature of the fluid at each of the plurality of temperature sensors as the DEF in the tank is undergoing a phase change during a change in operational characteristics of a power supply having an exhaust aftertreatment system that uses the DEF. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein the controller is configured to detect the changes in the temperature of the fluid as a phase change is occurring during starting of the power supply in ambient temperatures colder than normal operating temperatures for the power supply. ### Claim 20 A method of detecting contamination in Diesel Exhaust Fluid (DEF) contained within a tank including a plurality of temperature sensors arranged along a fluid column defined within the tank, the method comprising: detecting a temperature of the fluid at each of the plurality of temperature sensors along the fluid column; determining temperature gradients along the fluid column from the temperatures detected by the plurality of temperature sensors; detecting changes in the temperature of the fluid at each of the plurality of temperature sensors along the fluid column as a function of time as the DEF in the tank undergoes a phase change; determining a trend in the temperature of the fluid from at least one of the temperature gradients along the fluid column and the changes in the temperature of the fluid as a function of time; comparing the trend in the temperature of the fluid with data from a reference sample of DEF; and taking action that includes one or more of adding a chemical to contaminated DEF, diluting contaminated DEF, and replacing contaminated DEF.