There are multiple methods utilized to detect leaks, we recommend you to use a helium leak detector and isolate the system into small parts making sure each section is leak tight to your specification. The key is to reduce the flow of the helium tracer gas to make sure you pin point and repair any leaks in each individual section tested. Eventually, you’ll be able to isolate the vacuum system from the installation and by a process of elimination you’ll be able to find the source of the leak.