The weight tolerance of match weighed filters references the maximum difference in weight from the test (top) filter and the control (bottom) filter. A stated tolerance of 50µg means that the control filter may differ in weight no more than 50µg from the test filter. This is important to know during post sample weighing as the weight tolerance of the 2 filters needs to be considered when calculating results.
During manufacture, filters with matched weights (within the given tolerance) are inserted into the
cassette in random order. Thus, it is possible for the control filter to weigh more than the test filter
before sampling (within the given tolerance). If the control filter still weighs more after sampling, a sample likely was not collected. Please check your equipment for proper operation and pump flow.