Use the graph or tables below to determine the range of air leakage you can test with the Cobra using our standard orifice plates.

Note that the data is based on laboratory tests with short lengths of hard pipe attached to the duct leakage tester. Actual field performance will likely result in reduced performance due to: (1) amount of flexible duct used; (2) number of bends in flexible duct; (3) size of duct system; (4) line voltage. To account for flexible duct and 90 degree bends, use our program that takes these in-line losses into account.

25 mm Orifice Plate

System Static Pressure (pa)Min Leakage (L/s)Max Leakage with Lynx Tester (L/s)
250415
500414
750413
1000411
125048
150045
200040

50 mm Orifice Plate

System Static Pressure (Pa)Min Leakage (L/s)Max Leakage with Lynx Tester (L/s)
2501661
5001659
7501657
10001650
12501640
15001625
200016-

75 mm Orifice Plate

System Static Pressure (Pa)Min Leakage (L/s)Max Leakage with Lynx Tester (L/s)
25039165
50039160
75039150
100039135
125039110
15003965
200039-

100 mm Orifice Plate

System Static Pressure (Pa)Min Leakage (L/s)Max Leakage with Lynx Tester (L/s)
25083260
50083255
75083240
100083215
125083175
150083110
200083-

Min Leakage is the recommended minimum flow rate based on a 100 Pa pressure drop across the orifice plate. For example, approximately 39 L/s through the 75 mm orifice plate results in a 100 Pa, so 39 L/s is the recommended minimum leakage. Although it is possible to measure an orifice plate pressure differential lower than 100 Pa, the accuracy of the resulting flow rate is decreased. Unit of L/s is equal to liters per second.