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LPG Data

Definitions and Technical Data
for LPG, Natural Gas and LPG/Air Mixtures


The following definitions, conversion factors, tables, and other information for and about propane, butane and propane/butane mixtures are compiled from commonly available sources and are reproduced for convenience only. While we exercised great caution during the compilation, we can not guarantee accuracy and urge everybody to verify the correctness of the data before using them. Also, we appreciate if you alert us of any errors you find.

   
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Definitions  
   
Miscellaneous Tables  
Standby Plant Sizing Chart

Cost Savings through Standby Plants

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THEORETICAL COMPATIBLE PROPANE/AIR MIXTURES

The table below shows Propane/Air mixtures, compatible with natural gas with several different specific gravities and calorific values.
All figures are approximate and are given for Propane with specific gravity of 1.53 and calorific value of 2516 BTU/cuft.
  

Natural Gas

Propane / Air Mixture

SGU

BTU/cuft

% LPG

% Air

SGU

BTU/cuft

0.56

800

47.54

52.46

1.252

1196

850

50.87

49.13

1.270

1280

900

54.24

45.76

1.287

1365

950

57.65

42.35

1.306

1450

1000

61.11

38.89

1.324

1538

1050

64.62

35.38

1.342

1626

1100

68.16

31.84

1.361

1715

1150

71.76

28.24

1.380

1805

1200

75.40

24.60

1.400

1897

0.58

800

46.62

53.38

1.247

1173

850

49.88

50.12

1.264

1254

900

53.18

46.82

1.282

1338

950

56.52

43.48

1.300

1422

1000

59.90

40.10

1.317

1507

1050

63.33

36.67

1.336

1593

1100

66.80

33.20

1.354

1681

1150

70.32

29.68

1.373

1769

1200

73.88

26.12

1.392

1859

0.60

800

45.76

54.24

1.243

1151

850

48.95

51.05

1.259

1232

900

52.18

47.82

1.276

1313

950

55.45

44.55

1.294

1395

1000

58.76

41.24

1.311

1478

1050

62.12

37.88

1.329

1563

1100

65.51

34.49

1.347

1648

1150

68.95

31.05

1.365

1735

1200

72.43

27.57

1.384

1822

 

Natural Gas

Propane / Air Mixture

SGU

BTU/cuft

% LPG

% Air

SGU

BTU/cuft

0.62

800

44.93

55.07

1.238

1130

850

48.06

51.94

1.255

1209

900

51.23

48.77

1.272

1289

950

54.43

45.57

1.288

1369

1000

57.68

42.32

1.306

1451

1050

60.97

39.03

1.323

1534

1100

64.29

35.71

1.341

1618

1150

67.66

32.34

1.359

1702

1200

71.07

28.93

1.377

1788

0.64

800

44.15

55.85

1.234

1111

850

47.22

52.78

1.250

1188

900

50.32

49.68

1.267

1266

950

53.47

46.53

1.283

1345

1000

56.65

43.35

1.300

1425

1050

59.87

40.13

1.317

1506

1100

63.13

36.87

1.335

1588

1150

66.44

33.56

1.352

1672

1200

69.78

30.22

1.370

1756

0.66

800

43.41

56.59

1.230

1092

850

46.42

53.58

1.246

1168

900

49.47

50.53

1.262

1245

950

52.55

47.45

1.262

1322

1000

55.68

44.32

1.295

1401

1050

58.84

41.16

1.312

1480

1100

62.04

37.96

1.329

1561

1150

65.27

34.73

1.346

1642

1200

68.55

31.45

1.363

1725

   
Properties of

Natural Gas

Propane

Butane

Chemical formula   

CH4

C3H8

C4H10

Boiling point of liquid at atmospheric pressure

°F
°C

-259
-162

-44
-42

32
0

Specific Gravity of vapor (Air = 1)   

0.6

1.53

2.00

Specific Gravity of liquid (Water = 1)   

0.6

0.51

0.58

Calorific value @ 60 °F (15°C)

BTU/cuft
kcal/m3

1012
9005

2516
22,390

3280
29,190

BTU/gal
kcal/liter

  

91,690
6,100

102,032
6,790

BTU/lb
kcal/kg

  

21,591
11,995

21,221
11,790

Latent heat of vaporization

BTU/gal
kcal/kg

   

785

808

Liquid weight

lbs/gal
kg/liter

 

4.24
0.508

4.81
0.576

Vapor volume from 1 gallon of liquid at 60 °F
Vapor volume from 1 liter of liquid at 15 °C

cuft
m3

  

36.39
0.272

31.26
0.234

Vapor volume from 1 lb. of liquid at 60 °F
Vapor volume from 1 kg of liquid at 15 °C

cuft
m3

  

8.547
0.534

6.506
0.406

Combustible limits

% of gas in air

5 - 15

2.4 - 9.6

1.9 - 8.6

Amount of air required to burn 1 cuft. of gas
Amount of air required to burn 1 m3 of gas

cuft
m3

9.53

23.86

31.02

Ignition temperature in air

°F
°C

1200
650

920 - 1020
490 -   550

900 - 1000
480 -   540

Maximum flame temperature in air

°F
°C

3568
1964

3595
1980

3615
1991

Octane Number   

100

Over 100

92

All data is approximate. For actual properties of any particular batch, contact your fuel supplier.

   

Approximate Vapor Pressure in psig

Temperature

Propane    ---->    To    ---->    Butane

° F

° C

100%

95/5*

80/20

60/40

50/50

40/60

20/80

100%

-40

-40.0

3.6

1.3

                 

-30

-34.4

8

5.5

4.5

              

-20

-28.9

14

11

9.2

4.9

1.9

        

-10

-23.3

20

17

16

9

6

3.5

     

0

-17.8

28

24

22

15

11

7.3

     

10

-12.2

37

32

29

20

17

13

3.4

  

20

-6.7

47

41

36

28

23

18

7.4

  

30

-1.1

58

52

45

35

29

24

13

  

40

4.4

72

63

58

44

37

32

18

3

50

10.0

86

77

69

53

46

40

24

6.9

60

15.6

102

93

80

65

56

49

30

12

70

21.1

127

109

95

78

68

59

38

17

80

26.7

140

128

125

90

80

70

46

23

90

32.2

165

149

140

112

95

82

56

29

100

37.8

196

172

168

137

123

100

69

36

110

43.3

220

197

185

165

148

130

80

45

* HD5, Commercial Grade Propane

  

Temperature Conversion Table

°F

°C

- 50

- 45.6

- 40

- 40.0

- 30

- 34.1

- 20

- 28.9

- 10

- 23.3

0

- 17.8

+ 10

- 12.2

20

- 6.7

30

- 1.1

32

0

40

+ 4.4

50

10.0

60

15.6

70

21.1

80

26.7

90

32.2

100

37.8

110

43.3

120

48.9

130

54.4

140

60.0

150

65.6

160

71.1

170

76.7

180

82.2

190

87.8

200

93.3

212

100

Formula:

Degrees C = (°F - 32) x 5/9
Degrees F = 9/5 x °C + 32
   

BTU content of common fuels

   

Per Pound

Per Gallon

Propane

21,591

91,690

Butane

21,221

102,032

Gasoline

20,930

110,250

Fuel Oil #1

16,960

135,425

Diesel

18,500

142,800

Butane Equivalents

Unit 

BTU

Pound

Therm

Dekatherm

Cuft.

Gallon

1 Pound =

21,221

1

0.212

0.0212

6.50

0.208

1 Therm =

100,000

4.714

1

0.1

30.64

0.98

1 Dekatherm =

1,000,000

47.14

10

1

306.4

9.8

1 Cuft. =

3,280

0.1537

0.032

0.0032

1

0.03199

1 Gallon =

102,032

4.81

1.02

0.1020

31.26

1

          

General Information

1 Lb. Steam

970 BTU

1 Boiler HP (per hr)

33,475 BTU

1 Kilowatt Hour

3,412 BTU

1 Gallon, Water

8.337 lbs

1 Cubic Foot, Water

7.481 gallons

1 Cubic Foot

1,728 cubic inches

1 Gallon

231 cubic inches

Propane Equivalents

Unit

BTU

Pound

Therm

Dekatherm

Cuft.

Gallon

1 Pound =

21,591

1

0.216

0.0216

8.58

0.239

1 Therm =

100,000

4.622

1

0.1

39.7

1.10

1 Dekatherm =

1,000,000

46.22

10

1

397

11.0

1 Cuft. =

2,516

0.1164

0.025

0.0025

1

0.027

1 Gallon =

91,690

4.24

0.917

0.0917

36.39

1

   

Specific Gravity and Heat Content by Volume of LP Gas-Air Mixtures

Propane - Air Mixtures

% Propane

%
Air

Specific
Gravity

Gross BTU/cuft

100

0

1.530

2516

95

5

1.504

2390

90

10

1.477

2264

85

15

1.451

2139

80

20

1.424

2013

75

25

1.398

1887

70

30

1.371

1761

65

35

1.345

1635

60

40

1.318

1510

59

41

1.313

1484

58

42

1.307

1459

57

43

1.302

1434

56

44

1.297

1409

55

45

1.292

1384

54

46

1.286

1359

53

47

1.281

1333

52

48

1.276

1308

51

49

1.270

1283

50

50

1.265

1258

49

51

1.260

1233