Duct grease deposit detection devices, systems, and methods

Abstract

Automatic devices that determine when pollutant deposits have accumulated in ductwork may be employed to notify maintenance personnel or automated cleaning equipment of the need for ducts to cleaned or replaced. Various detection devices may be employed to detect a property of accumulated grease and generate an indication of an accumulation. The detection device may present a surface to the fume stream inside a duct. The surface may be cooled to a temperature that represents a worst case temperature so that the accumulation due to condensation on the detector surface is at least as high as the coolest surface in the ductwork which is being monitored. Alternatively, the detection device may be located external to the duct. The detection device may interrogate the surface of the duct through contact or noncontact measurements to determine the thickness of an accumulated grease layer on the interior of the duct.

1 - 24 . (canceled) 
     
     
         25 . A system for detecting fouling in a duct, comprising:
 a member with a surface in an exhaust stream;   a device configured to generate a signal indicating a fouled condition of the surface due to a change in a property of the surface indicative of fouling wherein the property is reflectivity;   wherein the surface is one of a mirror, a diffuse reflector, and a retroreflector material.   
     
     
         26 . The system of  claim 25 , further comprising a device to cool the surface. 
     
     
         27 . The system of  claim 25 , further comprising a device to cool the surface to a predetermined temperature. 
     
     
         28 . The system of  claim 25 , wherein the device configured to generate a signal is effective to compare a measured property trend with a predetermined trend to identify a correlation. 
     
     
         29 . The system of  claim 25 , wherein a controller is used to take a sample measurement when an exhaust system is not operating. 
     
     
         30 . The system of  claim 25 , wherein a light source and a light detector are located on a same side of the duct wherein the light is reflected back from the surface to the detector. 
     
     
         31 . The system of  claim 30 , wherein the surface faces the light source and light detector. 
     
     
         32 . The system of  claim 25 , wherein the surface is a mirror. 
     
     
         33 . The system of  claim 25 , wherein the surface is a diffuse reflector. 
     
     
         34 . The system of  claim 25 , wherein the surface is a retroreflector material. 
     
     
         35 . The system of  claim 25 , further comprising a low profile arm supporting said member in the exhaust stream. 
     
     
         36 . The system of  claim 25 , wherein an orientation of said surface of the member is such that the surface faces an oncoming flow of fumes. 
     
     
         37 . The system of  claim 25 , wherein an orientation of said surface of the member is such that the surface is in a worst-case position for exposure to contaminants in the exhaust stream. 
     
     
         38 . The system of  claim 30 , wherein the light detector is a single-use light detector configured to be disposed after the signal indicating a fouled condition is generated. 
     
     
         39 . The system of  claim 25 , wherein the member is a single-use member configured to be disposed after the signal indicating a fouled condition is generated. 
     
     
         40 . The system of  claim 25 , wherein the surface is a single-use surface configured to be disposed after the signal indicating a fouled condition is generated. 
     
     
         41 . The system of  claim 25 , wherein the exhaust stream includes filterable particles of flammable grease. 
     
     
         42 . The system of  claim 27 , wherein the predetermined temperature is determined based on at least one of a real-time model of a wall of the duct, a temperature of the exhaust stream, and ambient temperature.