L Rsmith Thomas Moyes

The regime of cryogenic technology has been generally taken to indicate temperatures colder than — 100°F (—73°C). Fluids such as liquid oxygen, nitrogen, hydrogen, helium, argon, methane, and ethane, with normal boiling points below — 100°F ( —73°C) are called cryogenic fluids.

For the pump designer, the cryogenic regime requires consideration of the effect of low temperatures on the properties of construction materials and the effect of varying shrinkage rates on critical fits and clearances. The problem is further complicated by the fact that cryogenic fluids are stored at near atmospheric pressure and must be pumped at or near their normal boiling point, so the only NPSH available is that due to the liquid level above the pump suction.

The history of commercial cryogenic pumping divides into two eras. The first, commencing in the early 1930s with the first liquid oxygen plant in the United States, was the period in which end-suction shaft seal pumps were developed and produced for pumping liquefied atmospheric gases, such as liquid oxygen, nitrogen, and argon. This industry grew until the late 1960s. Though continuing to grow, the explosive period appears to have ended.

The second era commenced in 1959 with the first transport of a commercial cargo of liquefied natural gas (LNG) from Lake Charles, La., across the Atlantic Ocean to England. This voyage, carrying an almost token quantity of 5000 m3 of LNG, inaugurated an era of international trade in liquefied hydrocarbon gases that has grown with astounding rapidity and seems still to be barely on the threshold of realizing its full potential.

Survival Treasure

Survival Treasure

This is a collection of 3 guides all about survival. Within this collection you find the following titles: Outdoor Survival Skills, Survival Basics and The Wilderness Survival Guide.

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