​A vacuum is a space void of air. Here, the pressure in a closed system is significantly lower than ambient pressure. A vacuum describes a space in which there is no matter.

​The preparation and documentation of proof that a method will reliably lead to the expected result within specific limits. The rquirements may extend for example to - definition of product, packing and equipment specifications as well as process descriptions. Manufacturer specification including in-process inspections, test methods in in-process and quality control. Validation includes qualification.

​Generic term for devices or apparatus that have an auxiliary, balancing or display function inside or at the end of a line (piping system or wiring). Originates from Latin. In early times the word was used, for example, for the ties and mounting parts used to connect the armaments and equipment of mercenaries and knights. It is still used, with a slightly different meaning, in the English language (arms or army). It now appears in modern technical vocabulary as the term for devices inside joined or connected cables. Auxiliary devices for display, operation or other functions. Dashboard panels = display panel, union ends = union for devices and piping. Equipment is also the generic term for valves, flowmeters or other devices integrated in piping.

Originates from Latin (shut-off device). A valve belongs to a group of equipment and has a clearly defined function. "A valve is a device that is integrated in a media-conveying line (pipe, tube, chute, etc.) in order to directly control or regulate a flow-capable working medium (fluid) and/or have an alterable influence over its volumetric flow." In this case, the term "control" refers to the manual or semi-automated determination of the direction, pressure or volume of the volumetric flow. "Regulation" refers to fully automated functions. In order to meet the different requirements for use and due to their historical development, valves are based on different functional principles. Their name is based on the typical shut-off element and the device assignment. Contrary to general worldwide usage, in DIN zones and the German-speaking area not all devices that have the function of a valve are referred to as valves. Only globe valves and diaphragm valves are valves in the context of the standard.
Valves are separated into two main groups, "linear valves" and "quarter turn valves":
Linear valves work on a linear basis and therefore represent an important prerequisite for high numbers of operations. Since further technical features affect the mechanical load capability of the valves, however, not all linear valves are necessarily suitable for higher cycle duties.
Quarter turn valves generally work based on a 90° limited partial rotation. Due to the mechanical stress that is only concentrated on small areas (seals and bearings), quarter turn valves are only suitable for low cycle duties.
Linear valves include: Globe valves (long- and short-stroke), diaphragm valves (full bore and weir type), gate valves (with open and closed housing, sliding gate, wedge-type flat slide, parallel slide, knife gate and tapered gate valves), piston valves and pinch valves.
Quarter turn valves include: Butterfly valves, ball valves, plug valves (also known as rotary plug valves, pivoting body valves or rotary valves).
 
In addition to these valves, there are undoubtedly various other types within different areas of application. These valves can usually be assigned to one of the above types, however. When used as a control valve, the stroke distance/volumetric flow ratio should be favourable. Control valves usually work continuously and should therefore be designed for high cycle duties. This is where quarter turn valves reach their performance limits. The volumetric flow characteristics of quarter turn valves also prevent them from being used as control valves. The geometric design of the flow channel in the pivoting body of ball and plug valves, however, enables a very good characteristic to be achieved (special versions). The mechanical problem, however, remains. Nevertheless, quarter turn valves are still used for control, for example as a cost-effective alternative in large nominal sizes (butterfly valves) or with high pressures and temperatures (plug and ball valves made from suitable materials).

​Vapour shocks occur when vapour is added to a liquid with a lower temperature in a closed system. The vapour condenses suddenly and creates a vacuum. The resulting liquids expands in the system.

​Verband der Elektrotechnik Elektronik Informationstechnik (association for electrotechnology, electronics and information technology)

​Verein Deutscher Ingenieure (Association of German Engineers)

​Association of German Machine and Plant Manufacturers.

​In biological terms a very small agent of disease which can only reproduce in and with aid of living cells.

​Is the ability of a substance to flow. I.e. how difficult it is for a liquid to move. The reciprocal value of viscosity is fluidity, which is a measure of how easily a liquid can flow.

​Unusable materials
Disposal of infectious waste e.g. by thermal disinfection. For disposal of chemicals, § 3, par. 2. of the German Waste Disposal Act applies.

​Brief pressure peak in a pipe which can cause serious damage to pumps, pipes and fittings. Usually a loud knock is also audible. Water hammer occurs more frequently and intensively in liquid media – in gases and steam the pressure peaks are absorbed at least partly by the compressibility of the medium so that the water hammer is "softer" and "flatter" than in liquids. The causes are often valves opening too quickly at simultaneously too high a pressure difference before and after the valve. Another cause may be too fast a startup of a strong pump. Simultaneous closing of several valves in a closed system has also been known to cause water hammer. Water hammer can be avoided but at least suppressed by startup-controlled pumps, position speed throttled valves and overcurrent/overpressure valves.

​Water for Injection purposes (aqua ad injectabile).
Pyrogen-free, sterile water.
WFI water according to DAB must be produced by distillation. WFI water according to USP can be made by reverse osmosis combined with an ion exchange or ultrafiltration.

​World Health Organisation of the United Nations (UN).
World Health Organisation, Avenue Appia, CH-1211 Genf 11.

​Dimensionless number
Necessary temperature increase to reduce the D-value by 90 % to 1/10 of the original value at the operating temperature. The Z-value depends on the type of micro-organisms and the product.