ASTM D287-22 Standard Test Method for API Gravity of Crude Petroleum and Petroleum Products (HydrometerMethod)

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Designation: D287−22

Standard Test Method for

API Gravity of Crude Petroleum and Petroleum Products

This standard is issued under the fixed designation D287; the number immediately following the designation indicates the year of

original adoption or, in the case of revision, the year of last revision A number in parentheses indicates the year of last reapproval A

superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

This standard has been approved for use by agencies of the U.S Department of Defense.

1 Scope*

1.1 This test method covers the determination by means of

a glass hydrometer in conjunction with a series of calculations

of the API gravity of crude petroleum and petroleum products

normally handled as liquids and having a Reid vapor pressure

(Test Method D323) of 14.696 psi (101.325 kPa) or less

Values are determined at existing temperatures and corrected to

values at 60 °F (15.56 °C), or converted to values at 60 °F, by

means of Adjunct toD1250Standard Guide for the Use of the

Joint API and ASTM Adjunct for Temperature and Pressure

Volume Correction Factors for Generalized Crude Oils,

Re-fined Products, and Lubricating Oils (API MPMS Chapter

11.1) These tables are not applicable to nonhydrocarbons or

essentially pure hydrocarbons such as the aromatics

1.2 The initial values obtained are uncorrected hydrometer

readings and not density measurements Values are measured

on a hydrometer at either the reference temperature or at

another convenient temperature, and readings are corrected for

the meniscus effect, the thermal glass expansion effect,

alter-nate calibration temperature effects and to the reference

tem-perature by means of the petroleum measurement tables; values

obtained at other than the reference temperature being

hydrom-eter readings and not density measurements

1.3 The initial hydrometer readings determined shall be

recorded before performing any calculations Then the

calcu-lations required in Section 9 shall be performed and

docu-mented before using the final result in a subsequent calculation

procedure (measurement ticket calculation, meter factor

calculation, or base prover volume determination)

1.4 The values stated in inch-pound units are to be regarded

as standard The values given in parentheses are mathematical

conversions to SI units that are provided for information only and are not considered standard

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use It is the responsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.

For specific warning statement, see8.5

1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for the Development of International Standards, Guides and Recom-mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

2 Referenced Documents

2.1 ASTM Standards:2

D323Test Method for Vapor Pressure of Petroleum Products (Reid Method)

D1250Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils: API MPMS Chapter 11.1

D1298Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Hydrometer Method

D6822Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Thermohydrometer Method

D7962Practice for Determination of Minimum Immersion Depth and Assessment of Temperature Sensor Measure-ment Drift

D8164Guide for Digital Contact Thermometers for Petro-leum Products, Liquid Fuels, and Lubricant Testing E1Specification for ASTM Liquid-in-Glass Thermometers E77Test Method for Inspection and Verification of Ther-mometers

1 This test method is under the jurisdiction of ASTM Committee D02 on

Petroleum Products, Liquid Fuels, and Lubricants and the API Committee on

Petroleum Measurement, and is the direct responsibility of Subcommittee D02.02

/COMQ, the joint ASTM-API Committee on Hydrocarbon Measurement for

Custody Transfer (Joint ASTM-API).

Current edition approved Dec 1, 2022 Published February 2023 Originally

approved in 1928 Last previous edition approved in 2019 as D287–12b (2019).

DOI: 10.1520/D0287-22.

2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or

contact ASTM Customer Service at service@astm.org For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on

the ASTM website.

*A Summary of Changes section appears at the end of this standard

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 United States

E100Specification for ASTM Hydrometers

E126Test Method for Inspection, Calibration, and

Verifica-tion of ASTM Hydrometers

E344Terminology Relating to Thermometry and

Hydrom-etry

E2251Specification for Liquid-in-Glass ASTM

Thermom-eters with Low-Hazard Precision Liquids

E2877Guide for Digital Contact Thermometers

2.2 API Standards:3

MPMS Chapter 9.1Test Method for Density, Relative

Density, or API Gravity of Crude Petroleum and Liquid

Petroleum Products by Hydrometer Method (ASTM Test

MethodD1298)

MPMSChapter 9.3Test Method for Density, Relative

Density, and API Gravity of Crude Petroleum and Liquid

Petroleum Products by Thermohydrometer Method

(ASTM Test MethodD6822)

MPMS Chapter 11.1Temperature and Pressure Volume

Cor-rection Factors for Generalized Crude Oils, Refined

Products, and Lubricating Oils (Adjunct to ASTMD1250)

2.3 ASTM Adjuncts:

Adjunct toD1250Standard Guide for the Use of the Joint

API and ASTM Adjunct for Temperature and Pressure

Volume Correction Factors for Generalized Crude Oils,

Refined Products, and Lubricating Oils: API MPMS

Chap-ter 11.1)4

3 Terminology

3.1 Definitions:

3.1.1 API gravity, n—a special function of relative density

60/60 °F (15.56/15.56 °C), represented by:

°API 5@141.5/~relative density 60/60 °F!#2 131.5 (1)

No statement of reference temperature is required, since

60 °F is included in the definition

3.1.2 hydrometer reading, n—the point on the hydrometer

scale at which the surface of the liquid cuts the scale

3.1.2.1 Discussion—In practice for transparent fluids this

can be readily determined by aligning the surface of the liquid

on both sides of the hydrometer and reading the Hydrometer

scale where these surface readings cut the scale (Hydrometer

Reading – Observed) For nontransparent fluids the point at

which the liquid surface cuts the Hydrometer scale cannot be

determined directly and requires a correction (Meniscus

Cor-rection) The value represented by the point (Meniscus

Read-ing) at which the liquid sample rises above the main surface of

the liquid subtracted from the value represented by where the

main surface of the liquid cuts the Hydrometer scale is the

amount of the correction or Meniscus correction This

menis-cus correction is documented and then subtracted from the

value represented by the Meniscus Reading to yield the

Hydrometer Reading corrected for the Meniscus (Hydrometer

Reading – Observed, Meniscus Corrected)

3.1.3 observed values, n—values observed at temperatures

other than the specified reference temperature; these values are only hydrometer readings and not density, relative density, or API gravity at those other temperatures

3.1.4 specific gravity, n—historical term, no longer used, which has been replaced by relative density.

3.2 Acronyms:

3.2.1 PRT—platinum resistance temperature device 3.2.1.1 Discussion—While there may be other types of

RTDs available, for Custody Transfer operations in conjunc-tion with other standards organizaconjunc-tions Platinum RTDs have been standardized on for their accuracy and discrimination

4 Summary of Test Method

4.1 This test method is based on the principle that the gravity of a liquid varies directly with the depth of immersion

of a body floating in it The floating body, which is graduated

by API gravity units in this test method, is called an API hydrometer

4.2 The API gravity is read by observing the freely floating ASTM hydrometer (calibrated for API gravity) and noting the graduation nearest to the apparent intersection of the horizontal plane surface of the liquid with the vertical scale of the hydrometer, after temperature equilibrium has been reached The temperature of the sample shall be read from a separate accurate ASTM thermometer placed in the sample, which meets either Specifications E1 or E2251 requirements or ASTM Digital Contact Thermometers, which meet Guide

E2877requirements The temperature determination device, be

it the bulb of a ASTM Thermometer (Specifications E1 or

E2251) or a sensor of a Digital Contact Thermometer (Guide

E2877) shall be placed at the same elevation (within the stated tolerances) as the hydrometer bulb

N OTE 1—Through various testings that Subcommittee D02.02 (Joint ASTM/API Subcommittee) measurement committee and others have conducted, it has been determined that temperature stratifications do exist vertically from top to bottom of a hydrocarbon container as well as across the diameter of the container Therefore, as temperature affects the viscosity as well as the fluid density, the buoyancy of the hydrometer floating in the liquid is therefore affected, clarifying procedures have been added to the Procedure section.

4.3 The observed hydrometer reading is corrected for the meniscus effect, the thermal glass expansion effect on the hydrometer, alternate calibration temperature effects and re-duced to the reference temperature by means of the petroleum measurement tables If necessary, the hydrometer cylinder and its contents are placed in a constant temperature bath to avoid excessive temperature variation during the test

5 Significance and Use

5.1 Accurate determination of the gravity of petroleum and its products is necessary for the conversion of measured volumes to volumes at the standard temperature of 60 °F (15.56 °C)

5.2 This procedure is most suitable for determining the API gravity of low viscosity transparent liquids This test method can also be used for viscous liquids by allowing sufficient time for the hydrometer to reach temperature equilibrium, and for

3 Available from American Petroleum Institute (API), 200 Massachusetts Ave.

NW, Suite 1100, Washington, DC 20001, http://www.api.org.

4 Available from ASTM International Headquarters Order Adjunct No.

ADJD1250-A1A2-E-PDF Original adjunct produced in 1983.

opaque liquids by employing a suitable meniscus correction.

Additionally for both transparent and opaque fluids the

read-ings shall be corrected for the thermal glass expansion effect

before correcting to the reference temperature

5.3 When used in connection with bulk oil measurements,

volume correction errors are minimized by observing the

hydrometer reading at a temperature as close to reference

temperature as feasible

5.4 Gravity is a factor governing the quality of crude oils

However, the gravity of a petroleum product is an uncertain

indication of its quality Correlated with other properties,

gravity can be used to give approximate hydrocarbon

compo-sition and heat of combustion

5.5 Gravity is an important quality indicator for automotive,

aviation and marine fuels, where it affects storage, handling

and combustion

6 Apparatus

6.1 Hydrometers, of glass, graduated in degrees API as

listed inTable 1 and conforming to SpecificationE100or as

listed inTable 2 and conforming to SpecificationE2251

6.1.1 The user should ascertain that the instruments used for

this method conform to the requirements set out above with

respect to materials, dimensions, and scale errors In cases

where the instrument is provided with a calibration certificate

traceable to a NMI (National Metrology Institute), the

instru-ment is classed as certified and the appropriate corrections for

the meniscus effect, the thermal glass expansion effect, and

alternative calibration temperature effects shall be applied to

the observed readings prior to corrections Instruments that

satisfy the requirements of this test method, but are not

provided with a recognized calibration certificate, are classed

as uncertified

6.2 Temperature Determination:

6.2.1 Thermometers (Glass), having a range from −5 °F to

+215 °F and conforming to the requirements for Thermometer

12F as prescribed in SpecificationE1

N OTE 2—The ASTM Gravity Thermometer 12F has 0.5 °F subdivisions

and allowable 60.25 °F scale error and is suitable for use in determining

temperature of bulk crude oil volumes, such as lease production tanks.

Additional thermometers conform to Specification E1 standard or

Speci-fication E2251 standard having a narrower range than the 12F or S12F

Thermometers may also be used, if they have similar performance

characteristics.

6.2.2 Alternate liquid measuring device (Thermometer

S12F) conforming to the requirements prescribed in

Specifi-cationE2251may be used, provided that the total uncertainty

of the calibrated system is no greater than when using

liquid-in-glass thermometers The stated repeatability and re-producibility values are not applicable if alternate fluids are used in the liquid-in-glass thermometers

6.2.3 Digital Temperature Sensors—Digital Contact

Ther-mometers of the PRT style shall meet the requirements of GuideE2877and may be used instead of glass thermometers with the following exceptions:

6.2.3.1 Thermocouples shall not be used

6.2.3.2 Thermistors shall not be used

6.3 Hydrometer Cylinder, transparent material (see 6.3.2) The inside diameter of the cylinder shall be at least 0.25 in (6.35 mm) greater (see A inFig 1) than the outside diameter of the hydrometer body and the temperature measuring device plus the separation interval specified in Fig 1and the height shall be such that the appropriate hydrometer floats in the test portion with at least 1 in (25 mm) clearance between the bottom of the hydrometer and the bottom of the cylinder, under all densities and temperatures Ensure that the hydrometer cylinder is cleaned after each use to ensure that no contami-nants remain

6.3.1 When using separate hydrometer (or thermohydrom-eter) and temperature measuring devices, care shall be exer-cised to ensure that neither interfere with each other and that they are not affected by external temperature effects The minimum separation distances as shown in Fig 1 shall be required These separation distances are a function of the diameters of the measuring devices and the minimum distance from the sides of the measuring chamber to minimize external thermal effects

where:

A = minimum separation interval specified in 6.3 between the inside diameter of hydrometer cylinder and the sum

of the OD of the hydrometer body plus the OD of temperature measuring device plus the minimum sepa-ration interval between devices of 0.25 in (6.35 mm), seeFig 1, and

B = minimum separation interval between measuring de-vices of 0.5 in (12.7 mm)

6.3.2 Hydrometer cylinders constructed of transparent ma-terials shall be resistant to discoloration or attack by the petroleum or petroleum product samples and shall not affect the material being tested They shall not become opaque under prolonged exposure to sunlight If the opacity prevents the

TABLE 1 Available Hydrometers Scaled, Degrees API

Designation Type API Range, deg Scale

Series Total Each Unit Division Error 1H to 10H long plain −1 to 101 12 0.1 0.1

21H to 40H short plain 0 to 101 6 0.1 0.2

41H to 45 H thermo 15 to 51 8 0.1 0.1

51H to 60H thermo −1 to 101 12 0.1 0.1

71H to 74H thermo −1 to 41 12 0.1 0.1

TABLE 2 Available Hydrometers Scaled, Degrees API (Low

Hazardous Liquid Type)

ASTM Hydrometer Designation

Type API Range,

deg Each Unit

Scale Division Error

observation of both devices then the hydrometer cylinder shall

be replaced before continuing with the test

6.3.3 The minimum separation intervals specified is to

prevent any capillary action between devices and to ensure that

external temperature effects are minimized on the values

determined for density and temperature

7 Temperature of Test (Limiting Conditions of Test)

7.1 The gravity determined by the hydrometer method is

most accurate at or near the standard temperature of 60 °F

(15.56 °C) Use this or any other temperature between 0 °F and

195 °F (–18 °C and + 90 °C) for the test, so far as it is

consistent with the type of sample and necessary limiting

conditions shown inTable 3

7.2 The purpose of Table 3 is to clarify what actions are

required to ensure that the sample does not change its physical

makeup during the testing period or modifications to the

sample physical properties to ensure that the devices can function properly For example, with highly volatile samples being measured in an open container the light ends may evaporate while the devices are reaching temperature equilib-rium This is a function of ambient temperature as well as fluid temperature and composition Conversely, if the fluid is too viscous (thick) the hydrometer may not float freely, which is a requirement for a buoyance device

8 Procedure

8.1 For referee testing, use the long plain form of hydrom-eter (1H to 10H) For field testing, the thermohydromhydrom-eter method in Test MethodD6822(API MPMS Chapter 9.3) is the

preferred method However, if the user desires to use a liquid-in-glass thermometer with low-hazard glass precision fluid as specified in Specification E2251or a Digital Contact Thermometer as specified in GuideE2877and6.2.3, the user

FIG 1 Separation Intervals (minimum requirements) between Devices and Hydrometer Cylinder

TABLE 3 Limiting Conditions and Testing Temperatures

Sample Type Gravity Limits Initial Boiling Point

Limits Other Limits Test Temperature Highly volatile lighter than 70° API Cool to 35 °F (2 °C) or lower in original closed

container.

Moderately volatile heavier than 70° API below 250 °F (120 °C) Cool to 65 °F (18 °C) or lower in original closed

container.

Moderately volatile and viscous heavier than 70° API below 250 °F (120 °C) Viscosity too high at

65 °F (18 °C)

Heat to minimum temperature for sufficient

fluidity.

Nonvolatile heavier than 70° API above 250 °F (120 °C) Any temperature between 0 °F and 195 °F

(−18 °C and 90 °C) as convenient Mixtures of nonpetroleum products or

essentially pure hydrocarbons

60 °F ± 0.25 °F (15.56 °C ± 0.1 °C)

can use Test MethodD6822(API MPMS Chapter 9.3) with a

modified procedure as detailed in 8.11of this test method

8.1.1 As shown inTable 1andTable 2, the user has access

to hydrometers covering various ranges of API gravity The

user should select a hydrometer which results in the liquid

interface cutting the hydrometer stem in the center third of the

range The hydrometer should not be used when the liquid

interface cuts the scale in the bottom two API gravity values or

at the top two API gravity values

8.1.2 When using digital temperature devices the user shall

utilize only intrinsically rated temperature devices that

con-form to the appropriate standard

N OTE 3—In practice whether in a lab or field environment this test

method is used in a potentially hazardous environment (that is, explosive)

and as these devices are electrically powered which could possibly

produce a spark, potentially resulting in an explosion/fire All companies

generally have Engineering and Operating standards that refer to NFPA

(National Fire Protection Association) and NEC (National Electrical

Code) codes that detail the requirements for the use of electrical devices

in classified areas These company requirements should take precedence.

8.2 Prior to lowering the selected hydrometer and/or

tem-perature determination instrument into the sample perform the

Equipment Validation enumerated in Annex A1

8.3 Verify that the selected density and/or temperature

determination instruments conform to the requirements of

Annex A2

8.4 Adjust the temperature of the sample in accordance with

Table 3 For field testing, test temperatures other than those

listed inTable 3may be used The hydrometer cylinder shall be

approximately the same temperature as the sample to be tested

8.5 Transfer the sample into the clean hydrometer cylinder

without splashing, so as to avoid the formation of air bubbles

and to reduce to a minimum the evaporation of the lower

boiling constituents of the more volatile samples (Warning—

Samples may be extremely flammable Vapors may cause flash

fire.) For the more volatile samples, transfer to the hydrometer

cylinder by siphoning (Do not start the siphon by mouth.)

Remove any air bubbles formed, after they have collected on

the surface of the sample, by touching them with a piece of

clean filter paper or other suitable means before inserting the

hydrometer For field testing, the gravity measurement is

directly made in the sampling core thief or hydrometer

cylinder Place the cylinder containing the sample in a vertical

position in a location free from air currents Take precautions

to prevent the temperature of the sample from changing

appreciably during the time necessary to complete the test

During this period, the temperature of the surrounding medium

should not change more than 5 °F (3 °C)

8.6 Lower the hydrometer gently into the sample and, when

it has settled, depress it about two scale divisions into the liquid

and then release it; keep the rest of the stem dry, as unnecessary

liquid on the stem changes the effective weight of the

instrument, and so affects the reading obtained With samples

of low viscosity, a slight spin imparted to the instrument on

releasing assists in bringing it to rest, floating freely away from

the walls of the hydrometer cylinder Allow sufficient time for

the hydrometer to become completely stationary and for all air

bubbles to come to the surface This is particularly necessary in the case of the more viscous samples

8.7 Lower the temperature measuring device slowly into the sample, in close proximity to the hydrometer installed in 8.6

making sure that neither touch, nor come in contact with the side walls of the sample cylinder Refer toFig 2a andFig 2b and Fig 3a and Fig 3b The temperature measuring device may also be used to cautiously and slowly stir the sample instead of the hydrometer, to minimize stratification

8.7.1 The hydrometer is a buoyancy device, its performance

or where it floats is dependent on the temperature of the fluid around the point of buoyancy Therefore, it is essential that the sample temperature be taken as close to this point of buoyancy

In practice with opaque samples this point can be difficult to determine However, it can be estimated from knowing the lengths of the various instruments and then estimating their relative positions

8.8 When the hydrometer has come to rest, floating freely, and the temperature of the sample is constant to within 0.2 °F (0.1 °C), read and record the hydrometer reading to the nearest scale division The correct reading is that point on the hydrometer scale at which the surface of the liquid cuts the scale Determine this point by placing the eye slightly below the level of the liquid and slowly raising it until the surface, first seen as a distorted ellipse, appears to become a straight line cutting the hydrometer scale SeeFig 4

8.9 To make a reading with nontransparent liquids, observe the point on the hydrometer scale to which the sample rises above its main surface, placing the eye slightly above the plane surface of the liquid This reading requires a correction Determine this correction (meniscus correction) for the par-ticular hydrometer in use by observing the height above the

where:

A = separation interval specified in6.3andFig 1,

B = separation interval specified in6.3andFig 1, and

C = relative vertical alignment between the density and temperature measuring devices (the bottom of the sens-ing portion of the temperature measursens-ing device should

be within 60.5 in (612.5 mm) and not more than 61.0 in (625 mm) of the bottom of the density sensor)

FIG 2 a Hydrometer and Liquid-in-Glass Thermometer Placement

(Typical)

main surface of the liquid to which the sample rises on the

hydrometer scale when the hydrometer in question is immersed

in a transparent liquid having a surface tension similar to that

of a sample under test SeeFig 5

8.9.1 Record the observed hydrometer scale readings to the

nearest 0.1° API for transparent liquids

8.9.2 When gravity readings have been observed on opaque liquids using the procedure given in8.9, subtract the meniscus correction from the hydrometer reading observed and record the meniscus corrected hydrometer scale reading to the nearest 0.1° API

where:

A = separation interval specified in6.3andFig 1,

B = separation interval specified in6.3andFig 1, and

C = relative vertical alignment between the density and

temperature measuring devices (the bottom of the

sens-ing portion of the temperature measursens-ing device should

be within 60.5 in (612.5 mm) and not more than

61.0 in (625 mm) of the bottom of the density sensor)

FIG 2 b Thermohydrometer and Liquid-in-Glass Thermometer

Placement (Typical) (continued)

where:

A = separation interval specified in6.3andFig 1,

B = separation interval specified in6.3andFig 1, and

C = relative vertical alignment between the density and

temperature measuring devices (the bottom of the

sens-ing portion of the temperature measursens-ing device should

be within 60.5 in (612.5 mm) and not more than

61.0 in (625 mm) of the bottom of the density sensor)

FIG 3 a Hydrometer and Digital Contact Thermometer (Typical)

where:

A = separation interval specified in6.3andFig 1,

B = separation interval specified in6.3andFig 1, and

C = relative vertical alignment between the density and temperature measuring devices (the bottom of the sens-ing portion of the temperature measursens-ing device should

be within 60.5 in (612.5 mm) and not more than 61.0 in (625 mm) of the bottom of the density sensor)

FIG 3 b Thermohydrometer and Digital Contact Thermometer

Placement (Typical) (continued)

FIG 4 Hydrometer Scale Reading for Transparent Liquids

(Typical)

N OTE 4—The meniscus correction for a particular hydrometer in use is

determined by observing the maximum height above the principal surface

of the liquid to which liquid rises on the hydrometer scale when the

hydrometer in question is immersed in a transparent liquid having a

surface tension similar to that of the sample under test.

8.10 Observe the temperature of the sample immediately

before and after the observation of the gravity, the liquid in the

cylinder being thoroughly but cautiously stirred with the

thermometer (Note 5), and the whole of the temperature thread

being immersed Should these temperature readings differ by

more than 1 °F (0.5 °C), repeat the temperature and gravity

observations when the temperature of the sample has become

more stable Record the mean of the thermometer reading

before and after the final hydrometer reading, to the nearest

1 °F, as the temperature of the test

8.11 When using a separate temperature measuring device

such as a liquid-in-glass thermometer; a liquid-in-glass

ther-mometer with low-hazard precision liquid or a digital contact

thermometer they shall be placed in the sample measurement

cylinder as shown inFig 2a andFig 2b as well asFig 3a and

Fig 3b

N OTE 5—When only thermohydrometers are used, stir the sample by

carefully moving the thermohydrometer in a side to side motion, without

immersing the thermohydrometer any lower into sample It is satisfactory

in this case to read the thermometer scale of the thermohydrometer after

the hydrometer reading has been observed Read the thermometer to the

nearest 1 °F (0.5 °C) If using a separate device to measure temperature,

use the temperature measuring device to stir the sample and read

according to 8.10

9 Calculation

9.1 Apply any relevant thermometer corrections to the temperature reading observed in8.10and record the average of those two temperatures to the nearest 1 °F

9.2 Application of the glass thermal expansion correction depends upon what edition of Adjunct to D1250 Standard Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and Lubricating

Oils (API MPMS Chapter 11.1) will be used to calculate the

base density

9.2.1 The 1980 version of the Adjunct toD1250Guide for

Petroleum Measurement Tables (API MPMS Chapter 11.1) has

the hydrometer glass thermal expansion correction included Input into the Adjunct toD1250Standard Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure Volume Correction Factors for Generalized Crude Oils,

Re-fined Products, and Lubricating Oils (API MPMS Chapter 11.1) software (see API MPMS Ch 11.1.1.3 paragraphs 5 and

6) requires the Hydrometer Reading – Observed or Hydrometer Reading – Observed, Meniscus Corrected in API units from

8.9.1 or 8.9.2, observed temperature of the sample, and the built-in hydrometer glass thermal correction switch set to “on” (0) or “off” (1) It will return API @ 60 °F

9.2.2 The 2004 version of the Adjunct toD1250Guide for

Petroleum Measurement Tables (API MPMS Chapter 11.1)

does not include the hydrometer glass thermal expansion correction, so that correction must be made before entering the Adjunct toD1250Standard Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined

Products, and Lubricating Oils (API MPMS Chapter 11.1)

software Depending on the specific end use of the calculation results, the final value may be left rounded or unrounded See

9.3 9.3 The following steps are required to implement9.2.2:

Step 1. Convert the meniscus corrected hydrometer scale reading to density in kg/m3using Eq 2

Hydrometer Scale Reading Units

Conversion to Density For API gravity:

density~kg / m3!5~141.5*999.016!/~131.51API! (2)

Leave the result unrounded

Step 2 Calculate the hydrometer thermal glass expansion

correction factor (HYC) using the appropriate equation below

(t is observed temperature).

Correction for a Base Temperature (T b) of 60 °F:

HYC 5 1.0 2@0.00001278~τ 2 60!#2@0.0000000062~τ 2 60!2#

(3)

Leave the result unrounded

Step 3 Multiply the hydrometer reading in kg/m3from Step

1 by HYC from Step 2 to obtain the glass expansion corrected hydrometer reading

kg/m3

FIG 5 Hydrometer Scale Reading for Opaque Fluids (Typical)

Step 4a Convert the hydrometer reading in density (kg/

m3HYC) from Step 3 to a R.D (relative density) hydrometer

reading

N OTE 6—The current C source code, compiled dll and Excel Add-in has

an omission and cannot use a kg/m 3 call with degree F.

R.D 5 kg/m3

Step 4b Input R.D and degree F into section 11.1.6.2 of the

Adjunct to D1250-04 Guide for Petroleum Measurement

Tables (API MPMS Chapter 11.1-2004) which returns R.D @

60 °F

N OTE 7—Pressure will have to be atmospheric gauge, or 0 psig as the

Adjunct to D1250 Standard Guide for the Use of the Joint API and ASTM

Adjunct for Temperature and Pressure Volume Correction Factors for

Generalized Crude Oils, Refined Products, and Lubricating Oils (API

MPMS Chapter 11.1) values are only valid at atmospheric pressure.

Step 4c Convert the calculated R.D value @ 60 °F to a

calculated API Gravity @ 60 °F usingEq 6

9.4 Future versions of the Adjunct toD1250Standard Guide

for the Use of the Joint API and ASTM Adjunct for

Tempera-ture and Pressure Volume Correction Factors for Generalized

Crude Oils, Refined Products, and Lubricating Oils (API

MPMS Chapter 11.1) code will be corrected so that it can

accept any combination of input units and return any

combi-nation of output units When available, the Adjunct to D1250

Standard Guide for the Use of the Joint API and ASTM

Adjunct for Temperature and Pressure Volume Correction

Factors for Generalized Crude Oils, Refined Products, and

Lubricating Oils (API MPMS Chapter 11.1) code can be

accessed directly from Step 3 and return API Gravity @ 60 °F,

R.D @ 60 °F, and kg/m3at any selected base temperature

Example 1

Observed Temperature: 77 °F

Observed Hydrometer Reading: 33.2 API Gravity

Observed Pressure: 0 psig

Base Temperature: 60 °F

Step 4c.1: 31.955643312 unrounded ( Eq 6 )

Step 4c.2: 32.0 °API rounded ( Eq 6 )

10 Report

10.1 Report the corrected hydrometer reading as degrees

API (°API) or as API Gravity

10.2 Report the final value as API gravity, at the reference temperature (nearest whole degree °F), to the nearest 0.1° API 10.3 The reporting values have no precision or bias deter-mination It is up to the user to determine whether this test method provides results of sufficient accuracy for the intended purpose

10.4 If the hydrometer readings are being used as an input to

a calculation process intended to return a volume correction factor for use in ticket or meter proving calculations, stop the calculation process identified above at Step 3 (if the density value is desired at flowing conditions) or Step 4 (if the density value is desired at base density conditions) and input the results into the calculation process

10.5 Certified hydrometers traceable to a NMI (National Metrology Institute), report the output density as ‘Density in Vacuo’

11 Precision and Bias

11.1 The precision of this test method as obtained by statistical examination of interlaboratory test results is as follows:

11.1.1 Repeatability—The difference between successive

test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed 0.2° API only in one case

in twenty

11.1.2 Reproducibility—The difference between two single

and independent results, obtained by different operators, work-ing in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed 0.5° API only in one case in twenty

N OTE 8—The precision for this test method was not obtained in accordance with RR:D02-1007.

N OTE 9—The precision for this test method only applies to measure-ments made with a liquid-in-glass thermometer.

N OTE 10—This precision statement applies only to measurements made

at temperatures differing from 60 °F (15.56 °C) by less than 18 °F (10 °C).

11.2 Bias—Bias for this test method has not been

deter-mined

12 Keywords

12.1 API gravity; crude petroleum; digital contact thermom-eter; hydromthermom-eter; thermohydromthermom-eter; thermometer

ANNEXES (Mandatory Information) A1 PERFORMANCE CHECK EQUIPMENT VALIDATION AS TO FIT FOR USE AT TIME OF TEST

A1.1 Immediately prior to determining test values the

den-sity and temperature measuring instruments being used for the

test shall be verified that they are “Fit for Use at Time of Test”

as delineated by the following procedures The specific

proce-dures the user shall use will be dependent on the specific test

instruments being used for that test

A1.2 These verifications shall be performed on each test

instrument immediately prior to each test being performed

A1.3 Each test instrument shall be in a clean condition prior

to the equipment validation so that each component of the Test

Instrument can be validated

A1.4 Equipment Validation Procedures

A1.4.1 Density Instruments:

A1.4.1.1 Hydrometers:

(1) Ensure that the hydrometer scale range selected for the

analytical test covers the expected density reading

(2) Inspect the hydrometer and ensure that it meets the

following requirements:

(a) The hydrometer glass shall contain no cracks, fissures,

deep scratches, rough areas, or other obvious damage

(b) The ballast at the bottom of the hydrometer shall

contain no loose components

(c) The ballast at the bottom of the hydrometer shall be

firmly affixed to glass envelope of the test instrument

(d) The paper scale within the hydrometer stem shall be

straight and without twist

(e) The paper scale within the hydrometer stem shall

contain an information label that documents the ASTM

hy-drometer designation, units of density, and a serial number

(f) The hydrometer shall contain a scale slippage

indica-tor and shall be positioned at the proper position relative to the

scale This is typically the whole unit value graduation mark

for the upper range the instrument is designed for

(3) If any of the items in A1.4.1.1(2) do not meet the

defined criteria, the instrument shall no longer be used and

shall be replaced

A1.4.1.2 Thermohydrometers:

(1) Ensure that the thermohydrometer scale range selected

for the analytical test covers the expected density reading

(2) Inspect the thermohydrometer and ensure that it meets

the following requirements:

(a) The thermohydrometer glass shall contain no cracks,

fissures, deep scratches, rough areas, or other obvious damage

(b) The ballast at the bottom of the thermohydrometer

shall contain no loose components

(c) The ballast at the bottom of the thermohydrometer

shall be firmly affixed to glass envelope of the test instrument

(d) The paper scale within the thermohydrometer stem

shall be straight and without twist

(e) The paper scale within the thermohydrometer stem

shall contain an information label that documents the ASTM hydrometer designation, units of density, and a serial number

(f) The thermohydrometer shall contain a scale slippage

indicator and shall be positioned at the proper position relative

to the scale This is typically the whole unit value graduation mark for the upper range the instrument is designed for

(3) If any of the items in A1.4.1.2(2) do not meet the

defined criteria, the instrument shall no longer be used and shall be replaced

A1.4.2 Temperature Instruments:

A1.4.2.1 Liquid-in-Glass Type Instruments:

(1) Ensure that the liquid-in-glass temperature instrument

scale range selected for the analytical test covers the expected temperature reading

(2) Inspect the liquid-in-glass temperature instrument to

ensure it meets the following requirements:

(a) The temperature instrument glass shall contain no

cracks, fissures, deep scratches, rough areas, or other obvious damage

(b) The temperature glass instrument shall contain

per-manent markings that document the ASTM temperature instru-ment designation and the instruinstru-ment’s serial number

(c) The liquid column is continuous from the fluid

reser-voir to the indicated temperature

(d) Ensure that the temperature scale and its graduation

markings are intact on the instrument

(3) If any of the items in A1.4.2.1(2) do not meet the

defined criteria, the instrument shall no longer be used and shall be replaced, with the exception of itemA1.4.2.1(2)(c) (4) If the liquid column is non-continuous, the temperature

instrument shall be placed in a liquid bath and the temperature

of the bath increased until it causes the liquid column to expand into the upper expansion area After this occurs, remove the temperature instrument from the liquid bath and cool the instrument down to ambient temperature Reverify that the liquid column is now continuous

(5) If the liquid column is now continuous verify that the

instrument still indicates the correct temperature in accordance

wiAnnex A2th If the column is non-continuous the instrument shall not be used, perform the procedure in A1.4.2.1(4) again

to try to re-unite the column and then re-verify perA1.4.2.1(5) A1.4.2.2 Digital Contact Thermometer:

(1) Inspect the Digital Contact Thermometer to ensure it

meets the following requirements:

(a) The temperature instrument sensor shall be a PRT

style meeting the requirements of GuideE2877

(b) The temperature instrument shall meet the

require-ments of 6.2.3of this test method

(c) Inspect the temperature instrument and ensure that all

components meet all mechanical and electrical requirements

(d) Perform an operational performance check in

accor-dance with the manufacturer’s requirements:

(1) Note—For digital contact thermometers being used

multiple times in a short period of time, such as determining

the temperature reading of multiple samples in a laboratory

over a very short interval (an hour or less) this step may be

skipped once it is performed once

(2) However, if an interval of 60 min or more is

experi-enced between analytical tests then this performance check is

required prior to any further testing

(3) Operational Performance Check:

(a) Verify that the device is in good working order.

(b) Verify that there is no mechanical damage to the

instrument case body, temperature sensor, or the connecting

wiring

(c) Verify that the battery voltage is in the manufacturer’s

recommended operating range

(d) Verify that the display(s) are legible.

(e) Verify that when turned on the temperature reading is

indicating a change and the change is indicating in the correct direction:

(1) The comparison device for the operational

perfor-mance check could be a liquid-in-glass thermometer; a pocket dial thermometer; an ambient air reading from a local source or other suitable source

(2) This check is intended to verify that the instrument is

working properly and not that it is measuring temperature accurately

(e) Verify that the temperature instrument shall have been

calibrated in accordance withAnnex A3

(2) The digital contact thermometer shall be calibrated in

accordance with Annex A3 if any of the requirements in

A1.4.2.2are not met prior to any use

A2 PERFORMANCE VERIFICATION OF DENSITY AND TEMPERATURE MEASURING INSTRUMENTS

A2.1 All density and temperature measuring instruments

shall be verified on a periodic schedule, which depends on the

frequency of use

A2.2 Verification Process—Verification is a process

whereby the working instrument is compared to another similar

device with a higher accuracy (lower uncertainty) This device

is typically referred to as a “Primary Verification Device or

Master Device”

A2.2.1 The Primary Verification Device shall have been

calibrated using standards traceable to a NMI (National

Me-trology Institute) and calibrated in accordance with the

appro-priate sections of Test MethodE126

N OTE A2.1—In the United States, the NMI is the National Institute of

Standards and Technology (NIST) and in Canada it is Measurement

Canada Many companies which supply hydrometers, thermometers to the

industry have the capability to provide equipment with NMI traceability.

A2.2.2 The calibration of the Primary Verification Device

shall be performed on an annual basis

A2.2.3 Verifications shall be performed using a liquid bath

both for density and temperature instruments

A2.2.3.1 A Primary Verification Device used with a test/dry

block may be substituted for a liquid bath for temperature

instruments, provided that it facilitates the ability to determine

the temperature readings of both the Primary Verification

Device and the working instrument without moving the

instru-ments within the test block

A2.3 Verification Test Points:

A2.3.1 Density Instruments:

A2.3.1.1 Test Method E126shall be used as the reference standard (for the calibration of the Primary Verification De-vice) for the verification of density instruments

A2.3.1.2 Density instruments shall be verified at two test points (approximately lower half and upper half on the hydrometer scale) on the density scale Test points shall be chosen to bracket the range of use

A2.3.1.3 For routine verification work, one may use a standard hydrometer as specified in Section 6 of Test Method

E126 and a reference fluid with similar surface tension and density of the liquids the hydrometer is intended to be used, see Table 2 in Test Method E126for guidance

A2.3.2 Temperature Instruments:

A2.3.2.1 Test Method E77 shall be used as the reference standard for the verification of temperature instruments

(1) Secondary standard thermometers as specified in 5.5 of

Test Method E77are more suitable for routine work

(2) Alternatively the user may also use a primary standard

thermometer as specified in 5.4 of Test MethodE77 A2.3.2.2 Temperature instruments shall be verified at two or more test points on the temperature scale Test points shall be chosen to bracket the range of use

A2.4 Frequency of Verification:

A2.4.1 Density Instruments:

A2.4.1.1 Hydrometers and thermohydrometers should be verified monthly (at a minimum they shall be verified quar-terly) for frequently used instruments (used four or more times

in a seven day period)

A2.4.1.2 Hydrometers and thermohydrometers should be verified bi-monthly (at a minimum they shall be verified every