Safetygram-7安全程序-7.docVIP

Safetygram-27安全程序-27 Cryogenic Liquid Containers低温液体容器 General概述 Cryogenic liquid containers, also referred to as liquid cylinders, are double-walled, vacuum vessels with insulation in the annular space. They are designed for the reliable and economic transportation and storage of liquefied gases at cryogenic temperatures, typically colder than –130 ?F(–90 ?C). There are two primary advantages of a liquid container. The first is that it contains a large volume of gas at a relatively low pressure compared to a compressed gas cylinder. The second is that it provides a source of cryogenic liquids which can be easily handled. Cryogenic liquid containers are often incorrectly referred to as dewars. Dewars are open, nonpressurized vessels for holding cryogenic liquids. 低温液体容器，也称为液体钢瓶，是双层的在环形空间内带有多层隔热的真空容器。它们设计用于低温，一般低于–130 ?F(–90 ?C)，液化气体的可靠而经济的运输和储存。液体容器有两个主要的优点。第一个是，同压缩气体钢瓶相比它能够在相对低的压力下容纳大量的气体。第二个是它提供了容易操作的低温液体源。低温液体容器经常被误称为杜瓦瓶。杜瓦瓶是用于容纳低温液体的开放式的不加压容器。 The cryogenic products normally found in liquid containers are liquid nitrogen (LIN), liquid argon (LAR), liquid oxygen (LOX), and liquid helium (LHE). Carbon dioxide and nitrous oxide are also available as refrigerated liquids in similar containers. 在液体容器里经常发现的低温产品是液氮(LIN)、液氩(LAR、液氧(LOX)和液氦(LHE)。在同样的容器里还可以装冷冻液体二氧化碳和一氧化二氮。 Although these containers are well insulated, heat will continuously leak into the product, due to the extremely large temperature difference between the cryogenic liquid and the ambient environment. The heat leak will cause some vaporization to occur. Vaporized product, if not used, will collect in the vapor space above the liquid and build pressure. This is referred to as head pressure. The head pressure will build in the container and periodically vent via the pressure relief valve. Vaporization rates will vary and may be as low as 0.4% or as high as 3% of the container’s volume per day. This is a normal and safe function of the container. 尽管这些容器隔热良好，由于在低温液体和周围环境之间的巨大的温差，热量会不断地泄露进产品。热泄露会导致发生一些蒸发。蒸发