Leybold UL-100 Helium Leak Detector is a self-contained, portable unit, and does not require liquid nitrogen. It is capable of detecting leaks into the minus ten range. Turbo Pump unit. The smallest detectable helium leak rate is 2 x 10 -10 mbar l/s. We provide rental and rebuild and repair services for the UL-100 and UL 100 Plus Helium Leak Detector.