getting to grips with COLD WEATHER OPERATIONS 寒冷天气运行(47)

B4.2 Fluid handling
● General
De-icing/anti-icing fluids are chemical products with an environmental impact. During fluid handling, avoid any unnecessary spillage, comply with local environmental and health laws and the manufacturer’s safety data sheet. Mixing of products from different suppliers is generally not allowed and needs extra qualification testing.
Slippery conditions due to the presence of fluid may exist on the ground or on equipment following the de-icing/anti-icing procedure. Caution should be exercised due to increased slipperiness, particularly under low humidity or non-precipitating weather conditions.
● Fluid handling equipment
The following information is generally valid for all types of fluid, but especially for Type II
and IV fluids.

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.

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.

● Storage
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. 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.
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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.
● Pumping
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.
　
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