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 method for detecting fouling in a duct connected to exhaust fumes from a kitchen hood, the method comprising:
 placing, in an exhaust stream flowing in said duct, a detection device in an exhaust duct of a kitchen exhaust hood with multiple detectors, each with a respective surface and each detector surface having a respective surface orientation or configuration;   the kitchen exhaust hood receiving fumes containing filterable particles of flammable grease;   the kitchen exhaust hood having a particulate filter at a position upstream of said device and effective to filter out said filterable particles; and   generating an output signal indicating a fouled condition of the surfaces due to a change in a property of the surfaces indicative of fouling.   
     
     
         26 . The method of  claim 25 , wherein the property is a thermal property of a material deposited on a respective one of the surfaces. 
     
     
         27 . The method of  claim 25 , wherein the property is an optical property of a material deposited on a respective one of the surfaces. 
     
     
         28 . The method of  claim 25 , wherein the surfaces include three surfaces and each is orthogonal to the other two. 
     
     
         29 . The method of  claim 25 , wherein one of the surfaces is shaded from the flow in the duct. 
     
     
         30 . The method of  claim 25 , further comprising displaying a level of accumulated contaminant on at least one of the surfaces.