Rectangular/Square Panel Dimensions
          
            
              
                
                  
                    | Nominal Size | Frame Inside | Frame Outside | Area | 
                  
                    | in | mm | in | mm | in | mm | in2 | cm2 | 
                
                
                  
                    | 9 x 12 | 230 x 305 | 9 x 12 | 230 x 305 | 13 x 16 | 330 x 406 | 98 | 630 | 
                  
                    | 12 x 18 | 305 x 457 | 12 x 18 | 305 x 457 | 13 x 16 | 406 x 559 | 201 | 1298 | 
                  
                    | 18 x 18 | 457 x 457 | 18 x 18 | 457 x 457 | 22 x 22 | 559 x 559 | 306 | 1976 | 
                  
                    | 18 x 24 | 457 x 610 | 18 x 24 | 457 x 610 | 22 x 28 | 559 x 711 | 411 | 2653 | 
                  
                    | 18 x 30 | 457 x 762 | 18 x 30 | 457 x 762 | 22 x 34 | 559 x 864 | 516 | 3330 | 
                  
                    | 18 x 36 | 457 x 915 | 18 x 36 | 457 x 915 | 22 x 40 | 559 x 1016 | 621 | 4008 | 
                  
                    | 18 x 46.5 | 457 x 1181 | 18 x 46.5 | 457 x 1181 | 22 x 50.5 | 559 x 1283 | 789 | 5091 | 
                  
                    | 19 x 59 | 483 x 1499 | 19 x 59 | 483 x 1499 | 23 x 63 | 584 x 1600 | 1082 | 6982 | 
                  
                    | 24 x 24 | 610 x 610 | 24 x 24 | 610 x 610 | 28 x 28 | 711 x 711 | 552 | 3562 | 
                  
                    | 24 x 30 | 610 x 762 | 24 x 30 | 610 x 762 | 28 x 34 | 711 x 864 | 693 | 4473 | 
                  
                    | 24 x 36 | 610 x 915 | 24 x 36 | 610 x 915 | 28 x 40 | 711 x 1016 | 834 | 5382 | 
                
              
             
           
            Note: Other vent or panel sizes, materials and burst pressures are available upon request – consult BS&B.  
          
          
	   
		
        
          Round Panel Dimensions
          
            
              
                
                  
                    | Nominal Size | Frame Inside | Frame Outside | Frame Angle | Area | 
                  
                    | in | mm | in | mm | in | mm | in | mm | in2 | cm2 | 
                
                
                  
                    | 16 | 406 | 16.25 | 412.75 | 19.75 | 501.65 | 1.75 | 44.45 | 192 | 1236 | 
                  
                    | 18 | 457 | 18.25 | 463.55 | 21.75 | 552.45 | 1.75 | 44.45 | 243 | 1568 | 
                  
                    | 20 | 508 | 20.25 | 514.35 | 23.75 | 603.25 | 1.75 | 44.45 | 301 | 1939 | 
                  
                    | 24 | 610 | 24.25 | 615.95 | 27.75 | 704.85 | 1.75 | 44.45 | 434 | 2799 | 
                  
                    | 30 | 762 | 30.25 | 768.35 | 34.25 | 869.95 | 2 | 50.8 | 680 | 4385 | 
                  
                    | 32 | 813 | 32.25 | 819.15 | 36.25 | 920.75 | 2 | 50.8 | 774 | 4992 | 
                  
                    | 36 | 915 | 36.25 | 920.75 | 40.25 | 1022.35 | 2 | 50.8 | 980 | 6325 | 
                  
                    | 40 | 1016 | 40.25 | 1022.35 | 44.25 | 1123.95 | 2 | 50.8 | 1211 | 7815 | 
                  
                    | 44 | 1118 | 44.25 | 1123.95 | 48.25 | 1225.55 | 2 | 50.8 | 1467 | 9462 | 
                
              
             
           
            Note: Other vent or panel sizes, materials and burst pressures are available upon request – consult BS&B.