The regime of cryogenic technology has been generally taken to indicate temperatures
colder than 100F (73C). Fluids such as liquid oxygen, nitrogen, hydrogen, helium,
argon, methane, and ethane, with normal boiling points below 100F (73C) are called
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 shrink-
age 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, com-
mencing 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 liq-
uefied 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 rapid-
ity and seems still to be barely on the threshold of realizing its full potential.
ATMOSPHERIC GASES _______________________________________________
Cryogenic pumps first came into being with the production of liquefied atmospheric gases
in commercial quantities. The initial liquefaction of air and the subsequent separation of
L. R. SMITH
In-flight refueling pump (J. C. Carter Company, Inc.)
oxygen and nitrogen d