Welding Gases

Acetylene  |  Air  |  Argon  |  Carbon Dioxide(C0 2)  |  Helium
Hydrogen  |  Nitrogen  |  Oxygen  |  Propane

Helium
Helium (He) is the second lightest element (hydrogen being the lightest) with a gaseous specific gravity of 0.138.  It is a colorless, odorless, tasteless inert gas at room temperature and atmospheric pressure. Its boiling point is -452.1F (-268.9C) at atmospheric pressure. Helium is present in dry air at a concentration of 0.0005%.

Helium is one of the noble gases.  Like the other noble gases, helium is chemically inert. Reactions with other elements occur only with difficulty and the resulting compounds are quite unstable.

Helium is the most difficult of all gases to liquefy and is impossible to solidify at atmospheric pressure. These properties make liquid helium extremely useful as a refrigerant and for experimental work in producing and measuring temperatures close to absolute zero.  Liquid helium can be cooled almost to absolute zero at normal pressure by rapidly removing the vapor above the liquid.

First discovered in the spectrum of the sun's corona during an eclipse in 1868, helium was first isolated from terrestrial sources in 1895. In 1907 British physicist Sir Ernest Rutherford showed that alpha particles are the nuclei of helium atoms.

Helium is the second most abundant element in the universe, after hydrogen; however, it is rare on earth.  Its principal source is natural gas wells where the helium is extracted from pockets in the crude natural gas stream and purified.   It  is so light that once released it escapes the earth's atmosphere and cannot be recovered. 

Helium is widely used as an inert gas in the arc welding process and as an inert gas in the production of reactive materials.  Its permeation rate and ease of detectability make it an ideal medium for leak detection.  Also, its low specific gravity and nonflammability allow its use in lighter-than-air applications such as the filling of balloons and blimps.   To reduce risk of the bends, a mixture of helium and oxygen is used as a breathing gas for deep-sea diving, since helium is less soluble in human blood than nitrogen.  Helium is also used in the pressurizing of rockets before takeoff and the pressurizing of tanks of rocket fuel. Liquid helium is used in superconducting magnet applications, including magnetic resonance imaging (MRI).

DOT Information     

DOT Name:         Helium
DOT Hazard Class:       Nonflammable Gas
DOT Label:       Nonflammable Gas
DOT ID No.:       UN1046
CAS No.:       7440-59-7
Valve Outlet:       CGA 580
         
Physical State in High Pressure Cylinder:   Gas
Major Hazards:       High Pressure Suffocation
  Fire Potential:       Non-Flammable
         

Physical Properties of Helium

Formula:       He
Molecular Weight:       4.003 lb/mol
Specific Volume at 70F and 1 atm:       96.71 ft3/lb (6.00 m3/kg)
Specific Heat:       4.97 BTU/lbmol-deg F@ 70 deg. F
Specific Gravity:       .138
Gas Density:       .010346 lb/ ft3 @ 70 deg. F. 14.7 PSIA
         

Boiling Point 

Temperature:        -452.1 deg. F (-268.9 deg. C)
Liquid Density:       7.804 lb./ft3
Latent Heat:       8.778BTU/lb.
         
     Critical Point
Temperature:       -450.3 deg. F
Pressure:       33.2 PSIA
         

Melting Point

Temperature:       455.8 deg. F
Pressure:       .0735 PSIA

 

Cubic Feet Per Balloon

BALLOONS Latex Mylar Large Weather Balloons
Size: 9" 10" 11" 12" 14" 16" 20" 36" 18" 26" 4' 5' 8' 12' 20'
Volume (ft3): .27 .30 .50 .52 1.00 1.25 2.42 4.14 .44 1.5 33 65 268 905 4189

Formula:Volume in cubic feet = 4/3 pi r3
                                               1728 

Balloons per Cylinder

BALLOONS Latex Mylar
Cylinder 9" 10" 11" 12" 14" 16" 20" 36" 18" 26"
22 ft3 81 73 44 42 22 17 9 5 50 14
58 ft3 214 193 116 111 58 46 23 14 131 38
110 ft3 407 366 220 211 110 88 45 26 250 73
137 ft3 507 456 274 263 137 109 56 33 311 91
219 ft3 811 730 438 421 219 175 90 52 497 146
286 ft3 1059 953 572 550 286 228 118 69 650 190

Helium High Pressure Cylinders
*Denotes light-weight aluminum cylinder

PART
NUMBER

CYL.
SIZE

WEIGHT
OF GAS (LBS.)

APPROX.
WT. OF FULL
CYLINDER (LBS.)

PRESSURE
(PSI @ 70F)

GALLONS

LITERS

DIMENSIONS
(Height x Diameter)

HELE*

22 ft3

.225

9

1800

165

623

30" x 4-1/2"

HEL058*

58 ft3

.59972

22

1800

436

1642

27" x 8"

HEL110

110 ft3

1.1374

58

2265

823

3115

47" x 7"

HEL110*

110 ft3

1.1374

44

2265

823

3115

41" x 8"

HEL137*

137 ft3

1.41658

42

2265

1030

3880

47" x  8"

HEL219

219 ft3

2.26446

135

2265

1638

6202

51" x 9"

HEL286

286 ft3

2.95724

160

2200

2150

8099

55" x 9-1/4"

 

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