Active samplers are devices that use external energy (compressed air, electricity) to move the product to be sampled to a different location.
Similar to a screw conveyor during material transport, the screw sampler transports the sample from the process to a downstream collection system. The longer the screw is in operation, the larger the sample. As a rule, screws have an influence on the particle size distribution, as individual particles are ground.
With piston samplers, material samples of equal volume/size are conveyed through a collecting pipe from the process into a downstream collection system. Each stroke of the piston delivers the same quantity. Piston samplers are also used for liquids, e.g. Mod. ILS.
The functionality of a cup sampler comes closest to the approach of a human being: Open the hole in the downpipe, hold the cup in the downpipe, pull it out and fill the sample into a bottle. Close the hole.
It is obvious that cup samplers can only be used with downpipes, otherwise this mode of operation is very gentle, brings uniform quantities of the product and leaves no constrictions in the downpipes. The samples are highly representative.
With passive samplers, the sample flows automatically into a downstream collection system due to physical conditions. The devices themselves only open the way so that the sample can flow. This function can be performed manually or with the aid of external energy (compressed air, electricity). Almost all valves are passive systems.
Openings from which the sample exits automatically due to gravity or pressure.
mostly used for liquids and available in different sizes and materials. Whatever can flow will do so even if it is not desired. So make sure that valves are leak-free. (Otherwise drips!)