Comparison of Calculation Standards of NGL and LPG

BCP 10A / BCG 10A Temperature corrections for NGL & LPG An analysis of different standards used for calculations of NGL and LPG volumes comparison with GPA TP-27

02.02.2009

Notes: © Copyright 2009 QuantityWare GmbH. All rights reserved.

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Contents BCP 10A / BCG 10A ..................................................................................................................... 1

TEMPERATURE CORRECTIONS FOR NGL & LPG ................................................................... 1

Notes: ............................................................................................................................... 2

Contents ........................................................................................................................... 3

Introduction ....................................................................................................................... 5

1. Types of calculations .................................................................................................... 6 1.1. Calculation of an appropriate base density .................................................. 6 1.2. Calculation of a CTL factor............................................................................. 6

2. Standards currently in use ............................................................................................ 7 2.1. GPA Technical Publication TP-27 ................................................................ 7 2.2. Petroleum Measurement Tables, ASTM D 1250-80 .................................... 7 2.3. Petroleum Measurement Tables 33 and 34, ASTM D 1250-80 Volume XII. 9

3. Comparison between standards ................................................................................. 10 3.1. Ranges and accuracy/rounding of the standards ....................................... 10 3.2. Statistics of the comparison ........................................................................ 13 3.3. Analysis of the comparison statistics .......................................................... 13 3.4. Dependencies between density, temperature and accuracy ..................... 14

4. Conclusion .................................................................................................................. 15 The QuantityWare Recommendation: ............................................................... 15

5. References ................................................................................................................. 16

Appendix 1 ...................................................................................................................... 17

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ASTM D 1250-80 table 23B against GPA TP-27 table 23E .............................. 17 ASTM D 1250-80 table 24B against GPA TP-27 table 24E .............................. 18 ASTM D 1250-80 table 53B against GPA TP-27 table 53E .............................. 19 ASTM D 1250-80 table 54B against GPA TP-27 table 54E .............................. 20 ASTM D 1250-80 table 59B against GPA TP-27 table 59E .............................. 21 ASTM D 1250-80 table 60B against GPA TP-27 table 60E .............................. 22

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Introduction For custody transfer purposes, NGL (Natural Gas Liquid) and LPG (Liquefied Petroleum Gas) measurements are stated at a fixed base temperature and saturation pressure; however most volume transfers occur at temperatures and pressures other than the defined base conditions. In these cases, such volumes must be adjusted to base conditions through the use of correction factors. A full correction can be performed using a correction factor for temperature (CTL) and a correction factor for pressure (CPL). Different standards are used for the calculation of these factors. Pressure correction factors are not within the scope of this paper, but can be calculated using the American Petroleum Institute Manual of Petroleum Measurement Standards (MPMS) Chapter 11.1-2004/2007. This paper analyzes the ranges and limits of different standards for the calculation of CTL factors as well as the density at base conditions, and compares the results against the most modern available standard.

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1. Types of calculations Two types of calculations can be distinguished: 1.1. Calculation of an appropriate base density The calculation of an appropriate base density, at the defined base temperature, relies on a measured density, at an observed temperature. Such calculation procedures generally also make use of CTL calculations (see chapter 1.2. herein). In daily business, the base density is usually determined in a laboratory using a product sample, instead of it being calculated separately for each business transaction using a standard’s tables or procedures. 1.2. Calculation of a CTL factor The calculation of a factor to correct the volume measured at any observed temperature to the volume at basis temperature. These tables and procedures are widely used in custody transfer processes.

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2. Standards currently in use Although NGL and LPG CTL can be calculated using a single modern standard f based on equations for the base temperatures of: -

60 degree Fahrenheit - 60°F

-

15 degree Celsius -15°C and

-

20 degree Celsius -20 °C,

Several historical standards are still in use, globally. This paper provides an analysis of the most common, but superseded standards, and provides a comparison of their calculated results against the standard currently recommended by the relevant standards organization. 2.1. GPA Technical Publication TP-27 GPA TP-27 is the current and most accurate standard for CTL calculations, which are utilized for volume quantity adjustments of NGL and LPG. It was released in September 2007 and supersedes all other standards, including GPA TP-25. Similar to ASTM D 1250-04/07 the calculation procedures based on 15°C and 20°C are based upon the 60°F procedures. This guaranties uniform, accurate results. GPA TP-27 contains two pairs of procedures (still called “tables”) for the three supported base temperatures: -

Tables 23E, 24E

60 °F / relative density

-

Tables 53E, 54E

15 °C / density in kg/m

3

-

Tables 59E, 60E

20 °C / density in kg/m

3

2.2. Petroleum Measurement Tables, ASTM D 1250-80 This standard clearly states that it is not to be used for NGL and LPG, however it contains equations instead of printed tables and supports base temperatures of 60 °F and 15 °C. Later extensions (tables 59 and 60) provide support for base temperatures of 20 °C. Tables 59 and 60 are modified versions of the of the 15 °C equations.

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The following tables are still widely in use for calculations of NGL and LPG: -

Table 23B, 24B

60 °F / relative density

-

Table 53B, 54B

15 °C / density in kg/m

3

-

Table 59B, 60B

20 °C / density in kg/m

3

The letter B stands for the product type “refined products” (e.g. jet fuel, gasoline, heating oil). Even the lowest densities of gasoline cannot support the densities required for NGL and LPG. However, since this standard is based on equations and software implementations exist, it is possible to extend the ranges by simply modifying the density and temperature range checks. The QuantityWare BCP 10A solution allows such range changes to be made via solutionspecific “SAP customizing” (a process known and understandable by projects, business and audit bodies), instead of forcing changes in source coding. As the QuantityWare solution is a fully integrated SAP Certified Solution, if calculations take place in customised ranges, a warning will appear in the application and also be stored in the appropriate material document. However, as QuantityWare’s BCP 10A is a complete calculations solution, GPA TP-27 is provided in the same package as the multiple ASTM D1250 implementations and should be used for NGL and LPG calculations where possible.

Note that standard ASTM D 1250 has not been developed nor designed to support calculations outside of the supported ranges required for NGL and LPG. Accuracy cannot be guaranteed if ranges are extended. In this document we will analyze and document the differences between ASTM D 1250 with extended ranges and the GPA TP-27.

More information about ASTM D 1250-80 can be found here: http://www.quantityware.com/_data/ASTM_D_1250___Historical_and_technical_overview_v3.pdf

The impact on business processes by using the ASTM D 1250-80 standard with extended ranges has been analyzed in the following document:

QuantityWare Case Study: LPG measurement standard selection

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2.3. Petroleum Measurement Tables 33 and 34, ASTM D 1250-80 Volume XII These are printed tables which were released as part of ASTM D1250 in 1952. The values are taken from the historic tables 23 and 24. Table 33 and 34 support a base temperature of 60 °F and relative density values. They were developed over a half-a-century ago for the convenience of the American liquefied petroleum gas and natural gasoline industries and are still in use owing to old agreements, although technically superseded.

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3. Comparison between standards Since GPA TP-27 is the most modern, accurate and recommended standard for NGL and LPG calculations, we will calculate data for the complete supported ranges of the superseded standards, and compare the results against those of GPA TP-27. 3.1. Ranges and accuracy/rounding of the standards The tables of GPA TP-27 support the widest ranges with the highest degree of accuracy.

Tables 33 and 34 are printed tables and have to be used as such. Interpolation of table 33 has been defined in the standard and is used accordingly. The values provided by those both tables are compared against GPA TP-27 results. A comparison outside the ranges of tables 33 and 34 is not possible.

The ASTM D1250-80 tables are provided as equations. These tables can only be used for NGL and LPG calculations when the temperature and density ranges have been extended. We will compare the whole range of GPA TP-27 against the extended ranges of ASTM D 1250-80.

The table below shows the ranges and the accuracy/rounding of the standards compared:

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Calculation based on 60 degree Fahrenheit:

Standard

Temperature

Temp.

(°F)

increment

Density (rel.)

Dens.

Rounding

increment

/ accuracy

(°F) Calculate base density at 60 °F and relative density GPA TP-27 table 23E ASTM table 33 ASTM D125080 table 23B

-50.8 to 199.4

0.1

30 to 90

1

0 to 200

0.1

0.3500 to 0.6880 0.490 to 0.650 0.6535 to 1.0760

0.0001 0.01 0.001 interp. 0.0005

0.0001

0.001

0.0001

Calculate volume correction factors CTL (observed to 60 °F) and relative density GPA TP-27

-50.8 to 199.4

table 24 E ASTM table 34 ASTM D125080 table 24B

0.1

-20 to 120

1

0 to 200

0.1

0.3500 to

0.0001

0.00001

0.005

0.001

0.6880 0.495 to 0.604 0.6535 to 0.7795

0.0005

0.00001 0.0001

Note: There are some gaps in the ranges of the ASTM tables 33 and 34. For more information, please refer to the standards.

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Calculation based on 15 degree Celsius:

Standard

Temperature

Temp.

Density

Dens.

Rounding

(°C)

increment

(kg/m3)

increment

/ accuracy

(°C) Calculate base density at 15 °C and density in kg/m3 GPA TP-27 table 53E ASTM D125080 table 53B

-46 to 93

0.05

210.0 to 740.0

0. 1

0. 1

-18 to 90

0.05

653.6 to 779.3

0. 5

0. 1

Calculate volume correction factors CTL observed to 15 °C at density in kg/m3 GPA TP-27 table 54E ASTM D125080 table 54B

-46 to 93

0.05

352.1 to 688.5

0. 1

0. 1

-18 to 95

0.05

653.6 to 778.8

0. 5

0. 1

Calculation based on 20 degree Celsius:

Standard

Temperature (°C)

Temp. increment

Density 3

(kg/m )

Dens.

Rounding

increment

/ accuracy

(°C) Calculate base density at 15 °C and density in kg/m3 GPA TP-27 table 53E ASTM D125080 table 53B

-46 to 93

0.05

210.0 to 740.0

0. 1

0. 1

-18 to 90

0.05

653.6 to 779.3

0. 5

0. 1

Calculate volume correction factors CTL observed to 15 °C at density in kg/m3 GPA TP-27 table 54E ASTM D125080 table 54B

-46 to 93

0.05

352.1 to 688.5

0. 1

0. 1

-18 to 95

0.05

653.6 to 778.8

0. 5

0. 1

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Note: There are some gaps in the ranges of the ASTM tables. For more information, refer to the 3

original standards documents. The density has been converted from kg/m to relative density for comparability. 3.2. Statistics of the comparison We compared all supported density and temperature pairs of the superseded standards used for NGL and LPG calculations with the results of the corresponding tables of GPA TP-27. The differences are calculated in percent. “Plus” means that the superseded table provide a larger result than GPA TP-27 and “Minus” that the result of the superseded table is smaller than that provided by GPA TP-27.

Table

Compared calls

Number of

Average +%

differences

Max +%

Average -%

Max -%

tab33

9.521

8.501

0,0345

1,9865

0,0200-

0,2657-

tab34

1.551

1.539

0,0600

1,2720

0,0620-

0,4872-

tab23b

1.429.923

1.408.763

0,7049

17,4000

1,4178-

13,4701-

tab24b

1.516.179

1.514.218

1,8802

88,6814

1,1240-

11,4943-

tab53b

9.480.361

9.383.997

0,5872

16,9463

3,8485-

33,7464-

tab54b

8.373.033

8.362.456

1,9005

87,0966

1,0832-

11,2294-

tab59b

10.071.095

9.977.902

0.7228

22.0012

4.0414

34.2454

tab60b

8.680.842

8.670.623

1,7343

92,7909

1,4864-

13,5735-

3.3. Analysis of the comparison statistics - Tables 33 and 34 The average differences of these printed tables are in a range that can generally be accepted. If buyer and seller agree to the ranges, accuracy and intervals of the values, these tables could still be used.

- ASTM D 1250-80, tables 23b, 24b, 53b and 54b The average and maximum differences are in a range which we would not recommend accepting in a custody transfer. Major differences start to appear when mainly the density (but also the temperature) is outside of the supported ranges.

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To decide whether these standards may be used or not, we must check the expected ranges of density and temperature at which custody transfers can take place. This will be done in the next chapter.

- ASTM D 1250-80, tables 58b and 60b The results are similar to the tables 53b and 54b for 15 °C. However these tables are a simple modification of the 15 °C equations and not a “soft conversion”; thus the differences are slightly larger than at 15 °C. 3.4. Dependencies between density, temperature and accuracy While tables 33 and 34 may still be acceptable, usage of the ASTM D 1250-80 tables tested above may be critical - dependent on the pressure and temperature ranges being used.

- ASTM D 1250-80 all tables with extended ranges In general, no differences should occur at the basis temperature, however when the observed temperature is different from the basis temperature, considerable differences start to emerge. Lower density has a high impact on the accuracy of calculations when compared to TP-27 and the differences increase with increasing distance to the base temperature. Thus the calculation using ASTM D 1250-80 will produce the biggest negative difference (smaller values) at the lowest density and temperature, and the biggest positive difference at the lowest density and highest temperatures.

In other words: -

Lower temperatures leads to lower results than GPA TP-27

-

Higher temperatures leads to higher results than GPA TP-27

-

These differences increases as the base density values decreases

We have made a general comparison over the entire ranges to show this density and temperature dependent behaviour. The results are listed in Appendix 1 of this document.

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4. Conclusion The values provided by ASTM tables 33 and 34 are similar to those calculated using GPA TP27; however the ranges supported by the tables are limited by density, temperature and printed intervals. This analysis is already present in great detail in GPA TP-27. As long as the provided values can coherently reflect the calculations needs of a specific business, and buyer and seller agree, these tables can still be used and the parties can expect to receive relatively realistic calculations results, if change to the new GPA TP-27 appears to costly. However, as recommended by the relevant standards organizations, new computer systems should use the most modern available standards.

The ASTM D 1250 tables can theoretically only be used for calculation of NGL and LPG when their ranges are extended outside of the officially published limits to much lower densities and lower temperatures.

The major issue when using ASTM D 1250 tables for NGL and LNG is that the calculations inaccuracy increases, the farther density and temperature distance themselves from the original standard ranges. This is easily seen by studying the tables in Appendix 1. The QuantityWare Recommendation: Usage of ASTM tables 33 and 34 does not reflect the accuracy that one would expect in the 21

st

century, but is still acceptable as long as the ranges are practicable for the business situation, both business parties and regulatory bodies agree to the standards usage, and the wording of existing contracts does not assume the usage of the latest available standards. Usage of a “manipulated“ ASTM D 1250-80 standard is very difficult to justify because of the inaccuracies in calculation and the existence of an alternate modern, proven standard . Thus, “manipulated” ASTM D 1250-80 implementations should be replaced by usage of the GPA TP-27.

More information about the impact on the custody transfer can be found here: QuantityWare Case Study: LPG measurement standard selection

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5. References 1. GPA Technical Publication TP-27. 2. Manual of Petroleum Measurement Standards, Chapter 11 – Physical Properties Data Section 1 - Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils, API 2004 3. Manual of Petroleum Measurement Standards Chapter 11.1, Volume X – Background. 4. ASTM D1250-80 Petroleum Measurement Tables, Volume XII, Tables 33 & 34. 5. ASTM D1250 – Historical Edition 1952 5. THE USE OF THE PETROLEUM MEASUREMENT TABLES – Manual of Petroleum Measurement Standards, Chapter 11.1 (API Std. 2540, ASTM D1250, IP200, ISO 91-1), revised October 1995, API 1995

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Appendix 1 ASTM D 1250-80 table 23B against GPA TP-27 table 23E

Temperature (°F)

ASTM D 1250-80 table 23B against GPA TP-27 table 23E Rel. density 60 °F/60 °F 0.35

-58 -48 -38 -28 -18 -8 2 12 22 32 42 52 62 72 82 92 102 112 122 132 142 152 162 172 182 192

-0.678 -3.205 -4.9948 -7.7053 -8.893 -9.7017 -10.4153 -11.075 -11.7087 -12.1501 -12.6143 -13.0625 -13.3607

0.4

6.6048 3.312 1.2847 -0.2732 -1.6133 -2.7602 -3.691 -4.4696 -5.1923 -5.8436 -6.371 -6.8409 -7.3132 -7.7332 -7.9442 -8.1504 -8.3333

0.45

0.5

0.55

0.6

0.65

10.3477 7.2718 5.3815 3.9216 2.7175 1.6485 0.6793 -0.1549 -0.8873 -1.5261 -2.0578 -2.5704 -3.0254 -3.4462 -3.7231 -3.9549 -4.1808 -4.4011 -4.5979 -4.7903 -4.9786

9.6232 7.9832 6.7405 5.6613 4.5361 3.5347 2.7139 2.0373 1.3877 0.8462 0.365 -0.0797 -0.4707 -0.811 -1.0845 -1.3133 -1.5544 -1.7531 -1.929 -2.1186 -2.1999 -2.2973 -2.3756 -2.4191 -2.4456

4.621 3.9187 3.2426 2.6751 2.1888 1.7787 1.3222 0.9575 0.6418 0.3723 0.147 -0.0363 -0.2149 -0.354 -0.4724 -0.571 -0.6335 -0.6947 -0.738 -0.7641 -0.7897 -0.815 -0.8238 -0.8165 -0.7307

1.9522 1.6072 1.2906 1.0557 0.8449 0.675 0.4738 0.3122 0.2059 0.1188 0.0504 -0.0166 -0.0329 -0.0653 -0.097 -0.0961 -0.0477 0.0158 0.0469 0.1086 0.1693 0.2292 0.3186 0.4067 0.4936

0.4421 0.3197 0.1998 0.1154 0.0653 0.0162 0 -0.0794 -0.0787 -0.078 -0.031 0.0154 0.061 0.121 0.1952 0.2684 0.3553 0.4559 0.5405

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ASTM D 1250-80 table 24B against GPA TP-27 table 24E

Temperature (°F) -58 -48 -38 -28 -18 -8 2 12 22 32 42 52 62 72 82 92 102 112 122 132 142 152 162 172 182 192

ASTM D 1250-80 table 24B against GPA TP-27 table 24E Relative density 60 °F/60 °F 0.35

0.4

0.45

0.5

0.55

0.6

0.65

-11.3834 -10.9971 -10.5877 -10.1281 -9.5991 -8.9857 -8.2467 -7.3159 -6.1362 -4.5736 -2.4117 0.751 5.9149 17.194

-6.4912 -6.2188 -5.916 -5.5835 -5.2122 -4.7907 -4.2963 -3.7089 -2.9951 -2.1359 -1.0553 0.303 2.063 4.4178 7.7436 12.8596 22.4255

-4.138 -3.9322 -3.7082 -3.4695 -3.2031 -2.9118 -2.5705 -2.1884 -1.7354 -1.2076 -0.5865 0.1597 1.0631 2.1566 3.5226 5.2312 7.4471 10.4105 14.6063 21.2176 34.7524

-2.4422 -2.3075 -2.1675 -2.0201 -1.8542 -1.667 -1.4643 -1.2319 -0.9646 -0.6674 -0.3227 0.0873 0.5544 1.1098 1.7631 2.533 3.449 4.5612 5.9126 7.5962 9.737 12.5316 16.3886 22.2045 32.9599

-1.1198 -1.0596 -0.9866 -0.9177 -0.843 -0.7518 -0.6607 -0.5581 -0.434 -0.3032 -0.1455 0.0351 0.2499 0.4942 0.7727 1.0925 1.47 1.9151 2.4289 3.0353 3.7518 4.591 5.5919 6.7986 8.268

-0.2136 -0.1979 -0.1857 -0.1761 -0.1597 -0.145 -0.131 -0.1167 -0.0925 -0.0658 -0.0357 0.008 0.0678 0.1248 0.2119 0.3103 0.4227 0.572 0.7412 0.9335 1.1744 1.448 1.7607 2.1401 2.5864

0.4398 0.4159 0.3926 0.3595 0.3184 0.2786 0.2305 0.1855 0.1341 0.0868 0.0348 -0.013 -0.0545 -0.0977 -0.1344 -0.1718 -0.1983 -0.2148 -0.2178 -0.2187 -0.2035 -0.1716 -0.1314 -0.0591 0.0248

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ASTM D 1250-80 table 53B against GPA TP-27 table 53E ASTM D 1250-80 table 53B against GPA TP-27 table 53E Density ( kg/m3)

Temp °C 210

260

310

360

410

460

510

560

610

660

710

-46

8.3928

4.0851

1.6333

0.2672

-0.5181

-41

7.2872

3.479

1.3571

0.1655

-0.5596

-36

6.3324

2.9766

1.124

0.0984

-0.5855

-31

13.8106

5.3662

2.5306

0.9503

0.0325

-0.5666

-26

9.4818

4.3713

2.1382

0.7627

0

-0.5332

-21

7.2699

3.5549

1.7171

0.5966

-0.048

-0.5002

-16

5.7071

2.8602

1.3662

0.4341

-0.1427

-0.4532

-11

4.4623

2.2776

1.0442

0.3266

-0.1573

-6

8.6648

3.4269

1.7155

0.7874

0.2213

-0.1561

-1

5.219

2.5122

1.2348

0.537

0.1349

-0.124

4

3.0737

1.5916

0.8104

0.3477

0.0836

-0.0923

9

1.4888

0.8014

0.439

0.181

0.0331

-0.0611

14

0.5609

0.2207

0.1309

0.0787

0.0179

0

-0.0152

19

-1.7468

-0.8835

-0.4711

-0.2327

-0.1062

-0.0163

0.0301

24

-3.4232

-1.8859

-1.0305

-0.5165

-0.2103

-0.0323

0.1048

-4.7715

-2.6849

-1.4885

-0.7554

-0.3122

-0.032

0.1785

-3.4283

-1.9117

-0.9698

-0.3779

0

0.2513

29

-9.6343

34

-32.0353

-20.0822

-10.9239

39

-32.0704

-20.7937

-12.112

-7.0362

-4.0776

-2.3219

-1.1609

-0.4425

0.0316

0.3232

44

-32.2239

-21.509

-13.1624

-7.9622

-4.6601

-2.7197

-1.3477

-0.4722

0.0783

0.4089

49

-32.4176

-22.2332

-14.132

-8.6584

-5.1825

-2.9543

-1.4944

-0.5348

0.1244

54

-32.7123

-22.9182

-15.0523

-9.2854

-5.6289

-3.2023

-1.6382

-0.5467

0.1699

59

-33.0204

-23.6266

-15.6009

-9.8877

-6.06

-3.4072

-1.7445

-0.5749

0.2455

64

-33.1581

-23.9782

-16.1276

-10.4272

-6.458

-3.6068

-1.8315

-0.5864

0.3048

69

-33.2516

-24.3183

-16.6739

-10.8574

-6.791

-3.8028

-1.8829

-0.5977

0.3634

74

-33.3769

-24.686

-17.1822

-11.2742

-6.988

-3.9759

-1.9504

-0.609

0.4362

79

-33.5389

-25.0635

-17.553

-11.6763

-7.1811

-4.1456

-1.9834

-0.5251

0.5232

84

-33.68

-25.3472

-17.9095

-12.0496

-7.3516

-4.3122

-1.9997

-0.474

0.6092

-25.6598

-18.309

-12.1918

-7.5377

-4.4076

-2.032

-0.4235

0.6941

89

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ASTM D 1250-80 table 54B against GPA TP-27 table 54E

Temperature (°C)

ASTM D 1250-80 table 54B against GPA TP-27 table 54E Density (kg/m3) 350

-46 -36 -26 -16 -6 4 14 24 34 44 54 64 74 84

400 -6.5046 -5.997 -5.3955 -4.6543 -3.665 -2.2818 -0.2505 2.9351 8.5672 22.2358

450 -4.1467 -3.7734 -3.3448 -2.8232 -2.1675 -1.2993 -0.1364 1.4864 3.8288 7.4175 13.5418 27.385

500 -2.4485 -2.2034 -1.9348 -1.6087 -1.2145 -0.7179 -0.0708 0.7695 1.8984 3.4403 5.5869 8.7565 13.789 23.4403

550 -1.1209 -1.0084 -0.8795 -0.7284 -0.544 -0.325 -0.0369 0.3381 0.8285 1.4658 2.3128 3.4261 4.9402 7.0076

600 -0.2124 -0.1879 -0.1618 -0.1405 -0.11 -0.0746 -0.007 0.0884 0.2238 0.4196 0.6908 1.0588 1.5486 2.1961

Comparison of calculation standards for NGL & LPG

650 0.4375 0.3972 0.3389 0.2647 0.1866 0.1005 0.009 -0.0739 -0.1429 -0.2025 -0.2269 -0.2178 -0.1668 -0.0637

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ASTM D 1250-80 table 59B against GPA TP-27 table 59E ASTM D 1250-80 table 59B against GPA TP-27 table 59E Density (kg/m3)

Temp.°C 210

260

310

360

410

460

510

560

610

660

710

-46

10.0887

4.7599

1.8599

0.3202

-0.5831

-41

8.7494

4.0657

1.5961

0.2003

-0.6242

-36

7.631

3.4811

1.3204

0.1158

-0.6498

-31

18.385

6.4858

2.9988

1.1242

0.0656

-0.6303

-26

12.2705

5.3444

2.5523

0.9324

0.0163

-0.5962

-21

9.37

4.3959

2.0982

0.727

-0.0322

-0.5626

-16

7.4122

3.6243

1.6774

0.5438

-0.1438

-0.5149

-11

5.9207

2.9495

1.3274

0.3992

-0.1744

-6

13.1286

4.6921

2.2998

1.0253

0.2922

-0.1887

-1

7.9921

3.6004

1.7581

0.7687

0.2043

-0.1717

4

5.1053

2.5122

1.2557

0.537

0.1349

-0.1394

9

3.1274

1.6147

0.8308

0.3661

0.0836

-0.1077

1.5653

0.8239

0.439

0.181

0.0331

-0.0611

14

4.0249

19

0.5045

0.2453

0.1309

0.0787

0.0179

0

-0.0152

24

-1.7468

-0.9308

-0.4925

-0.2327

-0.1062

-0.0163

0.0452

-3.4733

-1.9088

-1.0305

-0.5165

-0.2103

-0.0323

0.1048

-2.7519

-1.5089

-0.7554

-0.2949

-0.016

0.1785

29

-7.5143

34

-31.3225

-18.6047

-9.4887

39

-31.7866

-19.8845

-11.0234

-6.2014

-3.4928

-1.9719

-0.9884

-0.3779

0.0318

0.2661

44

-32.1667

-20.8995

-12.3413

-7.2813

-4.1612

-2.4005

-1.1793

-0.4425

0.0473

0.3379

49

-32.5348

-21.8168

-13.5348

-8.0932

-4.7843

-2.7006

-1.3656

-0.489

0.094

54

-32.9186

-22.6824

-14.6156

-8.8268

-5.2841

-2.9738

-1.5302

-0.5181

0.14

59

-33.2932

-23.4845

-15.2829

-9.5091

-5.7467

-3.2215

-1.656

-0.5467

0.1854

64

-33.4971

-23.9489

-15.9014

-10.1465

-6.1943

-3.4444

-1.7448

-0.5586

0.2455

69

-33.6295

-24.3604

-16.4973

-10.6441

-6.5923

-3.6622

-1.8318

-0.6027

0.3201

74

-33.7997

-24.7792

-17.0695

-11.1065

-6.8119

-3.8568

-1.9002

-0.5978

0.3938

79

-33.9905

-25.2048

-17.4979

-11.5338

-7.0461

-4.0474

-1.9339

-0.5453

0.4665

84

-34.1587

-25.5534

-17.9126

-11.968

-7.2561

-4.2335

-1.9841

-0.4936

0.5384

-25.8923

-18.3516

-12.1481

-7.443

-4.3478

-2

-0.4584

0.6243

89

Comparison of calculation standards for NGL & LPG

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ASTM D 1250-80 table 60B against GPA TP-27 table 60E

Temperature (°F) -46 -41 -36 -31 -26 -21 -16 -11 -6 -1 4 9 14 19 24 29 34 39 44 49 54 59 64 69 74 79 84 89

ASTM D 1250-80 table 60B against GPA TP-27 table 60E Density (kg/m3) 350 -11.0966 -10.8128 -10.518 -10.1988 -9.8536 -9.4566 -8.9929 -8.4509 -7.7974 -6.9881 -5.9777 -4.6793 -2.9532 -0.5832 2.9061 8.7204 22.8857

400 -6.7938 -6.5768 -6.3448 -6.0947 -5.8281 -5.5241 -5.1746 -4.778 -4.3225 -3.7759 -3.1363 -2.3583 -1.4263 -0.2595 1.1863 3.0583 5.5281 8.9846 14.2187 23.8879

450 -4.2934 -4.1317 -3.9611 -3.7797 -3.5852 -3.3639 -3.1218 -2.8542 -2.5452 -2.1981 -1.7947 -1.3249 -0.7851 -0.1394 0.6133 1.5201 2.612 3.9388 5.5807 7.6657 10.397 14.1254 19.6663 29.4299

500 -2.564 -2.4575 -2.3424 -2.2269 -2.1014 -1.9627 -1.8095 -1.6393 -1.4497 -1.2462 -1.0064 -0.7362 -0.4303 -0.0728 0.325 0.7903 1.3346 1.9623 2.6906 3.5512 4.5652 5.7961 7.2674 9.1012 11.4111 14.4558 18.6663 25.1603

550 -1.1502 -1.0995 -1.048 -0.9876 -0.9335 -0.8684 -0.7994 -0.7255 -0.6455 -0.5497 -0.4443 -0.3289 -0.1904 -0.0379 0.1423 0.3432 0.577 0.839 1.1443 1.4973 1.8961 2.3579 2.8933 3.5036 4.2143 5.0464 6.0262 7.1864

600 -0.1821 -0.1643 -0.16 -0.152 -0.1485 -0.1393 -0.1338 -0.1311 -0.1206 -0.1033 -0.0866 -0.0706 -0.0445 -0.007 0.0332 0.0854 0.1436 0.2279 0.3086 0.4195 0.5414 0.6886 0.8611 1.052 1.288 1.5506 1.8535 2.2048

Comparison of calculation standards for NGL & LPG

650 0.5056 0.4856 0.4645 0.4431 0.4121 0.3711 0.3316 0.2925 0.2452 0.2002 0.1575 0.1074 0.0615 0.01 -0.0372 -0.079 -0.1255 -0.1542 -0.1864 -0.2202 -0.2346 -0.2502 -0.2427 -0.2458 -0.224 -0.1876 -0.1461 -0.076

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