23.2 Fluid handling equipment
23.2.1 The following information is generally valid for all types of fluid, but especially for Type II and IV fluids:
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As the structure of Type II and IV fluids is relatively complicated to comply with several requirements, they are rather sensitive with regards to handling. The holdover time, as one of the most important criteria, is gained essentially by viscosity. The visco-elastic property of the fluid can be adversely affected by overheating, mechanical shearing and contamination by corroded tanks, in such a manner that the expected and required holdover times cannot be achieved. Therefore trucks, storage tanks and dressing plants have to be adequately conceived and maintained to comply with these requirements.
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Fluid shearing occurs when adjacent layers of fluid are caused to move relative to one another, whether in opposite directions or in the same direction at different speeds. This condition is unavoidable when pumping a fluid. For example, when merely moving a fluid through a pipe, fluid velocity ranges from zero at the pipe wall to a maximum at the center. Type II and IV fluids are damaged when the magnitude of shear is sufficient to break the long-polymer chains that make up the thickener. Therefore, specific equipment must be used.
23.3 Storage
23.3.1 Tanks dedicated to the storage of the de-icing/anti-icing fluid are required. The tanks should be made of a construction material compatible with the de-icing/anti-icing fluid, as specified by the fluid manufacturer. They should be conspicuously labeled to avoid contamination.
Issue II 02.07.2009 Rev. 0
23.3.2 Tanks should be inspected annually for corrosion and/or contamination. If corrosion or contamination is evident, tanks should be maintained to standard or replaced. To prevent corrosion at the liquid/vapor interface and in the vapor space, a high liquid level in the tanks is recommended.
23.3.3 The storage temperature limits must comply with the manufacturer’s guidelines. The stored fluid shall be routinely checked to ensure that no degradation or contamination has taken place.
23.4 Pumping
23.4.1 De-icing/anti-icing fluids may show degradation caused by excessive mechanical shearing. Therefore, only compatible pumps as well as compatible spraying nozzles should be used. The design of the pumping systems must be in accordance with the fluid manufacturer’s recommendations.
23.5 Transfer lines
23.5.1 Dedicated transfer lines must be conspicuously labeled to prevent contamination and must be compatible with the de-icing/anti-icing fluids to be transferred. An in-line filter, constructed according to the fluid manufacturer’s recommendations, is recommended to remove any solid contaminant.
23.6 Heating
23.6.1 De-icing/anti-icing fluids must be heated according to the fluid manufacturer’s guidelines. The integrity of the fluid following heating in storage should be checked periodically, by again referring to the fluid manufacturer’s guidelines. Such checks should involve at least checking the refractive index and viscosity.
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