A universal inlet adapter for a leak detection device using a pressurized detection media for detecting a leak in a fluid system having a fluid duct, the universal inlet adapter comprising: an inflatable bladder having a pair of opposed end wall portions (64, 66) and a tubular wall coupled to the pair of opposed end wall portions (64, 66), each end wall portion (64, 66) having an end wall internal surface and an opposed end wall external surface both of which being of annular configuration, the tubular wall being generically cylindrical and extending between the pair of opposed end wall portions (64, 66), the inflatable bladder having an internal reservoir and being selectively transitional between an inflated configuration and a deflated configuration, the inflatable bladder being configured to be engageable with the fluid duct to form a fluid tight seal therebetween as the inflatable bladder transitions from the deflated configuration to the inflated configuration; and a test fluid delivery tube extending through the inflatable bladder such that a portion of the inflatable bladder is disposed radially outward from the test fluid delivery tube, the test fluid delivery tube being fluidly connectable with the leak detection device for delivering the pressurized detection media into the fluid duct for testing; and a pair of rigid end caps (93, 93a; 95) connected to respective ones of the pair of end wall portions (64, 66) of the inflatable bladder; further wherein: each end wall portion defines an end wall thickness between the end wall internal surface and the end wall external surface; the tubular wall includes a tubular wall internal surface and an opposed tubular wall external surface to define a tubular wall thickness therebetween; characterized in that the end wall thickness of each end wall portion (64, 66) being at least approximately twice as large as the tubular wall thickness. an inflatable bladder having a pair of opposed end wall portions (64, 66) and a tubular wall coupled to the pair of opposed end wall portions (64, 66), each end wall portion (64, 66) having an end wall internal surface and an opposed end wall external surface both of which being of annular configuration, the tubular wall being generically cylindrical and extending between the pair of opposed end wall portions (64, 66), the inflatable bladder having an internal reservoir and being selectively transitional between an inflated configuration and a deflated configuration, the inflatable bladder being configured to be engageable with the fluid duct to form a fluid tight seal therebetween as the inflatable bladder transitions from the deflated configuration to the inflated configuration; and a test fluid delivery tube extending through the inflatable bladder such that a portion of the inflatable bladder is disposed radially outward from the test fluid delivery tube, the test fluid delivery tube being fluidly connectable with the leak detection device for delivering the pressurized detection media into the fluid duct for testing; and a pair of rigid end caps (93, 93a; 95) connected to respective ones of the pair of end wall portions (64, 66) of the inflatable bladder; further wherein: each end wall portion defines an end wall thickness between the end wall internal surface and the end wall external surface; the tubular wall includes a tubular wall internal surface and an opposed tubular wall external surface to define a tubular wall thickness therebetween; characterized in that the end wall thickness of each end wall portion (64, 66) being at least approximately twice as large as the tubular wall thickness. each end wall portion defines an end wall thickness between the end wall internal surface and the end wall external surface; the tubular wall includes a tubular wall internal surface and an opposed tubular wall external surface to define a tubular wall thickness therebetween; characterized in that the end wall thickness of each end wall portion (64, 66) being at least approximately twice as large as the tubular wall thickness.