GEMÜ glossary for valves and

automation components

GEMÜ glossary for valves and

Our glossary provides an explanation of around 400 technical terms and abbreviations relating to the pipeline construction sector. It focuses on valves, measurement and control systems and their areas of application.

I-controller more
​Controllers in which there is a proportional relation between the control error and the positioning speed.
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IAMFES more
​International Association of Milk, Food and Environmental Sanitarians
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In-process inspection more
​Inspection during the process Inspections determined by the manufacturer which are conducted in the course of manufacture of the product.
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Increased safety more
​Increased Safety is the guarantee that measures have been developped for electrical equipment, so that they can even be used  in areas at risk of gas explosion.
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Inert gas more
​Inert gases are gases which are extremely neutral due to their chemical properties.
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Inertization more
​Inertization isthe exchange or conversion of a reactive gas into an inert gas.
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Infect more
​Transmission and penetration of foreign organisms (e.g. parasites, bacteria, fungi) or viruses into an organism or a closed system.
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Inlet distance more
​The inlet distance is the length of a pipe in the flow to a flowmeter.
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Instrument sensor more
​Is a sensor which continuously measures a non-electrical variable and alters its internal electrical value according to the measured value, e.g. pressure or temperature sensors.
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Interbus more
​Interbus is a bus system specially required for  industrial use. It is used to transmit information to a company via a cable. Like a fieldbus, the interbus is a a communication connection between actuators / sensors and their control units, yet unlike the fieldbus system, it offers other advantages, such as faster and easier commissioning.
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Intercrystalline corrosion more
​Intercrystalline corrosion refers to corrosion within specific corrosive agents along the crystal boundaries of metal crystals, while the grains (metal crystals) themselves are hardly affected. During this process, the grains can separate from the grain structure, causing the steel to lose its solidarity.
Intercrystalline corrosion in stainless steel is caused by the dispersion of chromium-rich carbides at the crystal boundaries, which causes chromium depletion in neighbouring zones. These chromium carbide dispersions are triggered by extreme heat in the critical temperature range of 500 – 800 °C. Chromium nickel steels with a higher carbon content are particularly susceptible. So-called low-carbon steels (with a carbon content of less than 0.03%) have a high resistance to intercrystalline corrosion.
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Intrinsic safety more
​See ATEX
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Ion exchanger more
​An ion exchanger replaces cations or anions in a medium through the addition of other equivalent cations or anions. This is used e. g. for softening water.
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IP protection class more
​Is the protection of electrical equipment through housings, flaps and covers in order to guarantee personal protection. IP protection classes are standardized and stipulated in DIN EN 60529 . The aim is to prevent the penetration of water and particles into electrical equipment.
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ISO more
​​International Standardization Organisation
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ISPE more
​International Society for Pharmaceutical Engineering
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JIS more
​Japanese Industrial Standard
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Joint more
The linking/joining together of multiple parts/substances using mechanical, chemical or physical means.
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KBE more
​Kolonien bildende Einheiten - Colony forming unitsSee also Colony number.
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Kv more
​(VDI/VDE 2173 and DIN-ISO-EN): Kv is the flow coefficient of a valve and is expressed by a number. It is defined under uniform conditions and therefore creates a possibility for comparison and the mathematical basis for calculation in a different operating situation. A flow constant rsulting from a pressure difference of ∆p 1 bar, a test temperature of the ambient atmosphere and the fluid between 5° C and 30° C (usually 20° C) and the uniform liquid test medium with a density of 1000 kg/m3 and a kinematic viscosity of 10 -6 m2/s (water H2O) guarantee a comparability of the valves at a common denominator. The measuring result is expressed by a number. This number is the characteristic number of the valve. If no unit of measure is assigned to the characteristic number, this means that the characteristic number refers to cubic metres per hour (m3/h). If the characteristic number refers to another unit of measure, this unit of measure must be assigned directly to the characteristic number (e.g. 3200 l/h) All valves can be tested at a pressure freely selected by th manufacturer. Only the difference of p1 bar between the inlet side (p1) and the outlet side (p2) is to be determined. The diaphragm vlave is an exception. In this functional principle the test must always take place at the maximum permissible operating pressure of the respective valve (diaphragm stretch). The opening state of the valve is any so that a characteristic can be determined, for example, over the whole stroke range depending on the valve position. Formulae serve to take into account all the parameters and physical variables deviating from the test. Since liquids, gases and steam are subject to different laws, different formulae also exist. The standardised calculation formulae are very extensive, therefore the "simplified" formulae are normally used. Here it is important that they cannot be fully abbreviated and the unit used respectively for the value Q or the Kv value is identical. (See also CV for American version of Kv).
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KV more
​The KV measured value: Value of a single valve in any opening position
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Kv 100 more
​the KV measured value of a single fully open valve
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KV test pressure for all other valves more
​​p1 frei wählbar - 1 bar = ∆ p 1 bar
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KV test pressure for diaphragm valves more
​p1 Betrieb max - 1 bar = ∆ p 1 bar
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Kv value more
​The Kv value is a standardized variable. It is the measured flow Q of water (5 to 30 °C) in m3/h with a pressure loss of 1 bar and the respective stroke. The Kvs value is the flow with a rated stroke of 100%.
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Kvs more
​The planned KV measured value for an identical series of fully open valves
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