Apparatus and method for determining density of insulation

Abstract

An apparatus for determining the density of insulation in a cavity of a structure that senses a force of the insulation against the sensor. The force is used to determine the density of the insulation, which, in turn, is used to determine the thermal resistance or R-value of the insulation. The apparatus may include a fixture for supporting the sensor and holding the sensor in the substantially fixed position. A method for determining the density of loose-fill, blown-in-place insulation in a wall cavity by the use of a sensor is that measures a force exerted on the sensor by the insulation. The measured force is used to determine the density of the insulation. The thermal resistance of the insulation is determined from the known cavity depth and insulation density.

1 . An apparatus for determining the density of insulation in a cavity of a structure, comprising: 
 a sensor positionable adjacent insulation in a wall cavity, wherein the sensor exerts a force upon the wall insulation and measures the response of the insulation to said force, the response being used to the density of said insulation.    
     
     
         2 . The apparatus for determining the density of insulation of  claim 1 , wherein said apparatus is positioned in contact with the insulation.  
     
     
         3 . The apparatus for determining the density of insulation of  claim 1 , wherein said apparatus is positioned in close proximity to the insulation.  
     
     
         4 . The apparatus for determining the density of insulation of  claim 1 , further comprising: 
 a fixture supporting the sensor, the fixture holding the sensor in a substantially fixed position relative to the insulation.    
     
     
         5 . The apparatus for determining the density of insulation of  claim 4 , wherein the sensor is adapted to be supported outside the cavity against the insulation and netting.  
     
     
         6 . The apparatus for determining the density of insulation of  claim 1 , wherein the sensor is a load cell.  
     
     
         7 . The apparatus for determining the density of insulation of  claim 1 , wherein the sensor is a force transducer.  
     
     
         8 . The apparatus of  claim 7 , further comprising: 
 a contact plate, wherein the force transducer is adapted to measure force encountered by the contact plate when held against the insulation.    
     
     
         9 . The apparatus for determining the density of insulation of  claim 1 , wherein the sensor is in the form of a spring-force meter.  
     
     
         10 . The apparatus for determining the density of insulation of  claim 1 , further comprising: 
 an air cup adapted to be pressed against the insulation, and    an air pressure mechanism for creating an air pressure differential between the air cup and the atmosphere.    
     
     
         11 . The apparatus for determining the density of insulation of  claim 10 , wherein the sensor determines the air pressure in the air cup and relates that pressure to the density of the insulation.  
     
     
         12 . The apparatus for determining the density of insulation of  claim 11 , wherein the sensor determines the density of the insulation using a predetermined equation providing the relationship between the pressure in the air cup and the density of the insulation.  
     
     
         13 . The apparatus for determining the density of insulation of  claim 1 , wherein the sensor determines the density of the insulation using a predetermined equation providing the relationship between the force sensed and the density.  
     
     
         14 . The apparatus for determining the density of insulation of  claim 13 , wherein the force sensed is resistance to physical displacement.  
     
     
         15 . The apparatus for determining the density of insulation of  claim 13 , wherein the force sensed is air pressure.  
     
     
         16 . A method for determining the density of loose-fill, blown-in-place insulation in a cavity defined between framing members of a structure, the method comprising the steps of: 
 (a) providing a structure including framing members and a sheath forming at least one cavity having a known depth;    (b) covering an inner side of the cavity with netting;    (c) filling the cavity with insulation;    (d) sensing a force exerted on a sensor by the insulation;    (e) using the force to determine the density of the insulation; and    (f) determining the thermal resistance of the insulation from the known cavity depth and insulation density.    
     
     
         17 . The method of  claim 16 , further comprising the step of supporting the sensor within the cavity.  
     
     
         18 . The method of  claim 16 , further comprising the step of providing a fixture for supporting the sensor outside the cavity.  
     
     
         19 . The method of  claim 18 , wherein the fixture is in the form of a plate that supports the sensor against the netting and insulation.  
     
     
         20 . The method of  claim 16 , wherein the sensor is a force transducer.  
     
     
         21 . The method of  claim 16 , wherein the sensor is a load cell.  
     
     
         22 . The method of  claim 16 , wherein the sensor is an air pressure gauge.  
     
     
         23 . The method of  claim 16 , wherein the sensor is an air cup that is pressed against the netting and insulation and the method further comprises the step of introducing air into the air cup at a given source pressure, and wherein the measuring step (e) comprises the step of measuring air pressure in the air cup, the pressure being directly related to the density of the insulation behind the netting.