Coating booth for electrostatic application of pulverized materials

An assembly of a powder spray booth and at least one interchangeable portable filter module, said powder spray booth being adapted to receive an electrostatic spray means for spraying dray particulate powder material onto workpieces contained in the booth, said assembly comprising,

• first and second vertical walls and a floor angled downwardly from said first vertical wall toward said second vertical wall, said first vertical wall being connected to said floor by a spiral curved wall section, a ceiling connecting the top of said first vertical wall to the top of said second vertical wall, vertical end walls extending from said first vertical wall generally toward said second vertical wall,
• at least one interchangeable filter module, said module including a powder collection chamber, said powder collection chamber being disposed adjacent said second vertical wall, said booth and said powder collection chamber being separated by said second vertical wall, said second vertical wall extending downward from the ceiling so as to form a barrier to the flow of powder laden air from said booth into said powder collection chamber,
• an air inlet opening in said first vertical wall,
• said second vertical wall having a lower edge spaced from said floor so as to define a booth outlet opening adjacent the lower edge thereof providing an air flow path through which powder laden air is free to pass without significant restriction from said booth directly into said collection chamber;
• means for collecting oversprayed dry particulate powder material in the bottom of said powder collection chamber, said collecting means being operable to collect said powder material in a dry condition suitable for reuse in said electrostatic spray means,
• a clean air chamber sealed from the booth, said clean air chamber being located adjacent to and above said powder collection chamber, said clean air chamber having a clean air chamber opening from the powder collection chamber thereinto;
• filter means mounted adjacent said clean air chamber opening for preventing powder from entering said clean air chamber from said booth outlet opening while permitting air flow from the powder collection chamber into said clean air chamber;
• blower means having an inlet connected to said clean air chamber to create a negative pressure in said clean air chamber, whereby air flows downwardly in said booth and through said booth outlet opening directly into said powder collection chamber and then upwardly through said filter means into said clean air chamber,
• sealing means to sealingly secure said filter module to said booth outlet opening and to said blower means, and
• one wall of said filter module being located immediately adjacent said booth and being hinged at one side so that it is free to pivot outwardly into the interior of said booth in the event of an explosion within said filter module.