Boiling Point ― The temperature at which a liquid boils and turns into vapor. Pressure of the liquid is important; technically, the vapor pressure of the liquid must equal the liquid pressure. Thus, adding pressure will increase the boiling point temperature.

Cryogenic ― A term used to generally describe things at temperatures from -238°F (-150°C or 123K) to absolute zero.

Cryogenic Gas Vent ― Sometimes called a “keep-full” or vapor vent, this is a cryogenic device that allows vapor out of a system so that the volume in the system remains a liquid. Many have internal floats that shut off the venting when it encounters a liquid versus a gas.

Heat Leak ― An industry term used to describe the amount of heat transferred into a container. For pipe, it is expressed in BTU/hr-ft (Watts/meter). Heat leak sometimes is used to compare different products; however, like many specifications, it is important to make sure that the data is taken under similar conditions (for example, temperatures and external airflow). Example values may range from 0.5 BTU/hr-ft for vacuum jacketed pipe to 20 BTU/hr-ft for foam-covered pipe. For more detailed information, check out:

Laminar Flow ― Sometimes called streamline flow, this is when a liquid flow is in layers that are parallel to the direction of flow. This can create a temperature and velocity gradient in the fluid and usually occurs at lower velocities. Compare with Turbulent Flow.

Thermal Mass ― A measure of the ability to store thermal energy. In scientific terms, it usually is expressed as heat capacity. This affects both the time to heat an object up and to cool it down.

 Turbulent Flow ― At higher velocities, turbulent flow often occurs, which is when a liquid flow moves rapidly and its velocity and pressure at any given point fluctuates rapidly. Turbulent flow brings about higher heat transfer and may increase the pressure drops through piping. Compare with Laminar Flow. A more detailed discussion of cryogenic flow is available at:

Related: How to Choose the Right Cryogenic Line Size