The PAMAS S4031 is a portable particle counter for liquids. It is used for research and standard measurements in laboratories and test institutes and is adequate for indoor and field applications. The instrument can be applied for batch sampling or for online measurements. A wear resistant ceramic piston pump guarantees a constant flow. With a simple-to-use touch screen user interface, operation is easy and intuitive. Up to 32 free adjustable size channels may be selected and stored in the system. The system is equipped with an integrated battery for more than 3 hours operation and data storage of more than 4000 measurements.