A continuous purge nitrogen stream flows to each of the above potential leak sources. The individual outlet streams are combined at the N3 manifold. A small portion of the combined stream is fed to the hydrogen analyzer, which is calibrated for a range of 0 to 5% hydrogen. An alarm will sound if the hydrogen concentration exceeds 2.5%. Note that the gas leaks from the above sources are either hydrogen or reactor gas. The hydrogen concentration in the gas is very high (near 100%); therefore a rise in hydrogen concentration in the manifold gas is an indication of a leak. However, the analyzer cannot indicate the exact source of the leak.