​German Clean Air Act is a law in Germany, which determines the maximum values for emission and immission of a plant. TA-Luft is binding for approval authorities for approval of industrial plant and machinery. Old machines must achieve these values within a transition period or must be replaced.

​Since the manufacturer specifications for the maximum permissible operating temperature of the valves usually have to be considered in relation to an assumed ambient temperature of 20 °C (generally applied measuring constant), the following rules must be observed for the use of valves unless the manufacturer specifies other parameters. Regardless of this, the maximum ambient temperature specified by the manufacturer may not be exceeded even if the actual operating temperature of the medium should be small. This is due to the fact that too high an ambient temperature has a negative effect on parts and components of the valve which do not necessarily have direct contact with the working medium (e.g. electronic parts, control membranes, threaded connections etc.). If, contrary to this rule, a valve can be used at high operating pressures and at the same time increased ambient temperatures, these data must be confirmed by the manufacturer (e.g. in the technical data sheet, the offer and/or an order confirmation).
Operating temp.max.safe function = (operating temp.max. manufacturer spec. + 20 °C) - ambient temp.actual

​Under tension tear corrosion one understands a tear formation in metals due to tension/bending forces in which corrosive substances have a simultaneous effect on the tear area. Characteristic is a deformationless separation with intercrystalline or transcrystalline progress often without formation of visible corrosion products.
Three prerequisites for the formation of tension corrosion must be satisfied simultaneously:
a) The material used must exhibit a special tendency to tension tear corrosion (chrome-nickel steels).
b) Tensions must be available whereby load and inherent tension act in the same way.
c) A specific active solution must be available (chloride and alkaline hydroxide solution).
This susceptibility rises with increasing concentration of chlorine and temperature. In order to effectively counteract the tension tear corrosion one of the three factors which cause it must be eliminated. This is often only possible through the material, e.g. increase in the nickel content or reduction in the tensions by tempering. Chrome-nickel steels with a Si-content greater than 3.5 % have also proven effective.

​Is a plastic which can be heated as often as desired and, as a result, can be deformed plastically. The prerequisite is that the thermal temperature of destruction of the thermoplastic materials is not exceeded. It hardens into the new shape as it cools.

​Total number of micro-organisms which can be proven in a sample The total colony number is given as colony forming unit per millimetre (KBE/ml).

​Old term for total colony number, should not be used if possible.

​Is a flow of liquids and gases, in which large or small flow turbulences occur in the flow.

​Drinking Water Directive.
Directive for the quality requirements for drinking water and water for foodstuffs.

​The type of ignition protection describes electical explosion-proof operating equipment based on its form of protection. According to standards EN 50015 to  50021, the following type of ignition protection can be classified. Oil enclosure "o", overpressure enclosure "P", sand enclosure "q", flame enclosure "d", increased safety "e", intrinsic safety "e", intrinsic safety "i" or type of ignition protection "n".

​Ultrafiltration.
A pressure-operated membrane separating method; approx. separation range of materials with mol wt 1000 – 2 million according to particle sizes = 0.01 μm – 0.001 μm.

​Ultra-high temperature method.
Sterilisation method using ultra-high temperatures above 135 °C.

​Underwriters LaboratoriesIs the organization for testing products and technical devices in the USA. Similar to TÜV in Germany.

​Is ultra pure water, with higher requirements than distilled water. Ultra pure water is generated through reverse osmosis. It is required for the production of medication, computer chips or ICs.

Ultra-Filtration is a membrane filtration process that works with pressure. The pore size is <0,1, which enables small particles, macromolecular molecules, bacteria and viruses to be filtered out.

​Ultrasonic measurement is the level of flow measurement of a container or pipe with the help of ultrasonic waves. The reflections of these waves allow the level or flow to be determined.

Reverse osmosis
See RO

​UHT method using direct steam injection.
See also UHT.

​Biotechnological processes usually have to be prepared before their actual main process. These processes for preparing a substance are called upstream processing. Usually substrates, nutrient solutions, micro-organisms and enzymes are prepared here.

​​Ultra pure water, see ultra pure water

United States Department of Agriculture.
USDA issued the requirements for dairy machines and meat processing machines.

​United States Pharmacopeia.
Drugs and Medicines Register of the United States of America

​Accident prevention regulations