Extraction Fan Assembly for an Animal Husbandry Barn

Abstract

An animal barn includes air inlets which are filtered to extract pathogens and a plurality of extraction fans for generating an air stream so as to draw replacement air into the containment area through the air inlets. Each fan has a housing mounted in a wall with an outlet duct extending through the wall to an outlet opening outside the wall. A damper flap is mounted on the fan suspended by a hinge at an upper edge so as to extend in a closed position across the opening in a mounting plate. The damper flap is movable to an open position under forward air flow from the fan and closes against a resilient deformable seal to seal the damper flap to prevent reverse flow of pathogen contaminated air through the fan housing when the fan is shut off. An adjustable abutment member can act to hold the flap partly open against opposing wind forces during low fan operation.

1 . A fan construction for use in an animal husbandry barn where the barn comprises:
 a containment area;   a plurality of air inlets into the containment area where each air inlet has an air filter system for extraction from incoming air of pathogens so as to prevent transmission of disease to the animals;   and a plurality of extraction fan constructions for generating an air stream exiting the containment area so as to draw replacement air into the containment area through the air inlets;   each fan construction comprising:
 a fan housing; 
 a fan mounted in the housing; 
 and a damper flap assembly mounted on the fan housing, the damper flap assembly including: 
 a mounting plate having an opening through which the air passes and a flange surrounding the opening; 
 a damper flap suspended by a hinge at an upper edge and pivotal about the upper edge so as to extend in a closed position across the opening with an outer peripheral portion of the damper flap engaging the flange around the opening; 
 the damper flap being movable to an open position under forward air flow from the fan by pivoting on the hinge away from the flange; 
 and a resilient deformable seal between the outer peripheral portion of the damper flap and the flange arranged to seal the damper flap to prevent reverse flow of air through the fan housing. 
   
     
     
         2 . The fan construction according to  claim 1  wherein the seal is carried on the outer peripheral portion of the damper flap. 
     
     
         3 . The fan construction according to  claim 1  wherein the seal comprises a deformable fin. 
     
     
         4 . The fan construction according to  claim 1  wherein the mounting plate includes a top cover extending from the hinge over the top of the damper flap. 
     
     
         5 . The fan construction according to  claim 4  wherein top cover has down-turned flange to engage the damper flap and prevent pivotal movement of the damper flap beyond a predetermined angle. 
     
     
         6 . The fan construction according to  claim 1  wherein there is provided an abutment member for holding the damper flap in a slightly open position against opposing wind forces when the fan is operating at a low speed. 
     
     
         7 . The fan construction according to  claim 1  wherein the abutment member is retractable to allow closing of the damper flap. 
     
     
         8 . The fan construction according to  claim 6  wherein the abutment member is operable by a remote control device. 
     
     
         9 . The fan construction according to  claim 1  wherein there is provided a latch for providing a closing force for holding the damper flap in the closed position. 
     
     
         10 . The fan construction according to  claim 9  wherein the latch comprises a magnetic strip around the periphery of the damper flap and/or a magnet at the bottom of the flap. 
     
     
         11 . The fan construction according to  claim 1  wherein the damper flap comprises a flat panel which may be insulated. 
     
     
         12 . The fan construction according to  claim 1  wherein the damper flap assembly is mounted on outside end of the fan housing. 
     
     
         13 . The fan construction according to  claim 1  wherein the fan housing has an additional louver closure. 
     
     
         14 . The fan construction according to  claim 1  wherein the damper flap assembly is mounted on the fan housing at an inner end. 
     
     
         15 . The fan construction according to  claim 1  wherein there is provided a heating wire for heating the seal to prevent freezing. 
     
     
         16 . The fan construction according to  claim 1  wherein the air inlets are arranged on the wall and/or at the ceiling of the containment area communicating with a roof space above the containment area. 
     
     
         17 . The fan construction according to  claim 16  wherein each air inlet includes a filter assembly carried in the roof space. 
     
     
         18 . The fan construction according to  claim 1  wherein, apart from the inlets and the extraction fans, the containment area is sealed against ingress of pathogen containing air. 
     
     
         19 . A fan construction comprising:
 a fan housing;   a fan mounted in the housing;   the fan being operable at high speed and at low speed;   and a damper flap assembly mounted on the fan housing, the damper flap assembly including:   a mounting plate having an opening through which the air passes and a flange surrounding the opening;   a damper flap suspended by a hinge at an upper edge and pivotal about the upper edge so as to extend in a closed position across the opening with an outer peripheral portion of the damper flap engaging the flange around the opening;   the damper flap being movable to an open position under forward air flow from the fan when the fan is operating at low or high speed by pivoting on the hinge away from the flange;   wherein there is provided an abutment member for holding the damper flap in a slightly open position against opposing wind forces when the fan is operating at low speed.   
     
     
         20 . The fan construction according to  claim 19  wherein the abutment member is retractable to allow closing of the damper flap. 
     
     
         21 . The fan construction according to  claim 20  wherein the abutment is operable by a remote control device.