The Compressed Gas Association (CGA) specification G-9.1-1992, Type I, Grade D is considered the commercial gaseous helium standard.
Gaseous Helium
(Units in ppm (v/v) unless show otherwise)
Type II liquid helium, when passed through a 10 micron absolute filter at less than 5.2ºK is pure helium for which no analysis is necessary.
The water content of helium required for any particular grade and application may vary with intended use. If a specific limit is required, it should be specified as a limiting concentration expressed in ppm (v/v) or the dew point equivalent. Also note that the water content of grades 4.5 and higher will be about 10 ppm higher when supplied in Pyrex glass flasks.
The Quality Verification Levels apply only to gaseous helium. Impurity limits for liquid helium are not specified since sufficient technical data and analytical procedures are not available to warrant a definitive quantitative specification. The requirement for insuring that the loaded fluid in a container is liquid helium can be satisfied by analyzing the shipping container vent gas or by demonstrating that the temperature of the loaded fluid is below the hydrogen triple point 13.88K).
Helium Conversion Data
|
Helium
|
Weight
|
Gas
|
Liquid
|
|
Pounds
|
Kilograms
|
Cubic Feet
|
Cubic Meters
|
Gallons
|
Liters
|
|
Lb
|
Kg
|
SCF
|
Sm3
|
Gal
|
L
|
|
1 Pound |
1
|
0.4536
|
96.71
|
2.736
|
0.9593
|
3.631
|
|
1 Kilogram |
2.205
|
1
|
213.2
|
6.039
|
2.115
|
8.006
|
|
1 SCF Gas |
0.0103
|
0.00469
|
1
|
0.02832
|
0.009919
|
0.03754
|
|
1 Sm3 Gas |
0.3651
|
0.1656
|
35.31
|
1
|
0.3504
|
1.3257
|
|
1 Gal Liquid |
1.0423
|
0.4728
|
100.8
|
2.854
|
1
|
3.785
|
|
1 L Liquid |
0.2754
|
0.1249
|
26.63
|
0.7542
|
0.2642
|
1
|
SCF (standard cubic foot) and SM3 (standard cubic meter) gas measured at 1 atmosphere and 70ºF.
Liquid measured at 0ºF and saturated pressure.
Nm3 (normal cubic meter) gas measured at 1 atmosphere and 0ºC.
All values round to the nearest 4/5 significant numbers.
