Niskin-Type Plastic Water Sampler PWS features all plastic (PVC) design, consisting of a tube with two lids connected by a latex rubber tubing. The lids are kept open during descent, caring for a fair flushing of the sampling tube. The sampling tube is completely metal-free. The PWS on the one hand is the standard oceanographic sampler to be used on Multi Water Sampler/ Rosette/Carousel arrays and on the other hand it can be used as single or series instrument connected to a hydrographic wire. When used on a wire, a messenger(not incl.), dropped down the wire from the surface, releases the end stoppers for closure. For the use of several PWS in a row a second messenger below the first sampler is used to actuate a series of samplers along the wire. When operated as a single instrument without bottom weight, we recommend to use a Centered Mounting Rack (436 380 … 436 395) which cares for a vertical position of the sampler. Retrieve the water sample via the discharge cock/tube at the lower end of the sampler.