Abstract: Apparatus and methods are provided for testing and analyzing a plurality of stream sources to monitor for an upset condition in one of the stream sources. A manifold is provided having a plurality of manifold inlets and a manifold outlet. A plurality of sampling devices for sampling the plurality of stream sources are coupled to the manifold inlets to provide stream samples to the manifold. A controller is in electronic communication with each of the plurality of sampling devices for providing test samples in the manifold. The controller alternately operates the sampling devices in (1) a sequencing mode in which each test sample is a stream sample from one of the plurality of sampling devices or (2) an averaging mode in which each test sample is representative of an average of the stream samples from the plurality of sampling devices. An analyzer is coupled to the manifold outlet to receive the test samples from the manifold and analyze each test sample for the presence of the upset condition.