NISKIN BOTTLES
The most commonly used water-sampling bottle at present is the Niskin bottle, with spring-loaded end-caps with rubber washers. These are plastic (polyvinylchloride) bottles with stoppers at each end. The stoppers are held together by a rubber cord or spring that pulls them together from inside the bottle. The water-tight closures at both top and bottom, equipped with subsampling spigot and air vent, can be remotely triggered at pre-determined depths in the water column to collect seawater samples for discrete chemical and biological measurements. To cock these bottles, lanyards are used to pull the stoppers away from the bottle, leaving the bottle wide open for water to flow through. The bottle is tripped by activating a firing mechanism that releases the lanyard, allowing the stoppers to close on the bottle thereby trapping the seawater sample. Niskin bottles can capture a much larger volume of seawater than the older Nansen bottles. Reversing thermometers on Niskin bottles are mounted in a spring-loaded frame that rotates the thermometers at the same time that the Niskin bottle stoppers are closed. These are used with most rosette samplers, the most common arrangement for water bottles, where a single frame carries up to 36 water bottles. Water bottles are mounted in a single frame that is attached to the end of the oceanographic wire. This has an electrical conductor incorporated; the bottles can be closed when desired on electrical command from the deck.
Bottles/Flasks/Jars