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Tank blanketing, also referred to as tank padding, is the process of applying a gas to the empty space in a storage container. The term storage container here refers to any container that is used to store products, regardless of its size. Though tank blanketing is used for a variety of reasons, it typically involves using a buffer gas to protect products inside the storage container. A few of the benefits of blanketing include a longer life of the product in the container, reduced hazards, and longer equipment life cycles. ==Methods== In 1970, Appalachian Controls Environmental (ACE) was the world’s first company to introduce a tank blanketing valve. There are now many ready-made systems available for purchase from a variety of process equipment companies. It is also possible to piece together your own system using a variety of different equipment. Regardless of which method is used, the basic requirements are the same. There must be a way of allowing the blanketing gas into the system, and a way to vent the gas should the pressure get too high. Since ACE introduced its valve many companies have engineered their own versions. Though many of the products available vary in features and applicability, the fundamental design is the same. When the pressure inside the container drops below a set point, a valve opens and allows the blanketing gas to enter. Once the pressure reaches the set point, the valve closes. As a safety feature, many systems include a pressure vent that opens when the pressure inside exceeds a maximum pressure set point. This helps to prevent the container from rupturing due to high pressure. Since most blanketing gas sources will provide gas at a much higher than desired pressure, a blanketing system will also use a pressure reducing valve to decrease the inlet pressure to the tank. Although it varies from application to application, blanketing systems usually operate at a slightly higher than atmospheric pressure (a few inches of water column above atmospheric). Higher pressures than this are generally not used as they often yield only marginal increases in results while wasting large amounts of expensive blanketing gas. Some systems also utilize inert gases to agitate the liquid contents of the container. This is desirable because products, such as citric acid, are added to food oils the tank will begin to settle over time with the heavier contents sinking to the bottom. However, a system that utilizes nitrogen sparging (and then subsequently tank blanketing once the nitrogen reaches the vapor space) may have negative impact on the products involved. Nitrogen sparging creates a significantly higher amount of surface contact between the gas and the product, which in turn creates a much larger opportunity for undesired oxidation to occur. It is possible for nitrogen that is as much 99.9% free of oxygen to increase the amount of oxidation within the product due to the high amount of surface contact. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tank blanketing」の詳細全文を読む スポンサード リンク
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