Calibration Instrument for Air sampler NCAS-200 is mainly used to calibrate all microporous plankton samplers. The flow range is from 0 to 200 L/min and show a good flow accuracy in the range of � 2.5 %. It provides high precision of � 1 %. It can measure very quickly and accurately the flow of the sampler without increasing the load of the sampler, which results in large deviation of the flow before and after the test.