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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee Designation: D287 − 22 Standard Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer/Method)1 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* conversions to SI units that are provided for information only and are not considered standard 1.1 This test method covers the determination by means of a glass hydrometer in conjunction with a series of calculations 1.5 This standard does not purport to address all of the of the API gravity of crude petroleum and petroleum products safety concerns, if any, associated with its use It is the normally handled as liquids and having a Reid vapor pressure responsibility of the user of this standard to establish appro- (Test Method D323) of 14.696 psi (101.325 kPa) or less priate safety, health, and environmental practices and deter- Values are determined at existing temperatures and corrected to mine the applicability of regulatory limitations prior to use values at 60 °F (15.56 °C), or converted to values at 60 °F, by For specific warning statement, see 8.5 means of Adjunct to D1250 Standard Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure 1.6 This international standard was developed in accor- Volume Correction Factors for Generalized Crude Oils, Re- dance with internationally recognized principles on standard- fined Products, and Lubricating Oils (API MPMS Chapter ization established in the Decision on Principles for the 11.1) These tables are not applicable to nonhydrocarbons or Development of International Standards, Guides and Recom- essentially pure hydrocarbons such as the aromatics mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee 1.2 The initial values obtained are uncorrected hydrometer readings and not density measurements Values are measured 2 Referenced Documents on a hydrometer at either the reference temperature or at another convenient temperature, and readings are corrected for 2.1 ASTM Standards:2 the meniscus effect, the thermal glass expansion effect, alter- D323 Test Method for Vapor Pressure of Petroleum Products nate calibration temperature effects and to the reference tem- perature by means of the petroleum measurement tables; values (Reid Method) obtained at other than the reference temperature being hydrom- D1250 Guide for the Use of the Joint API and ASTM eter readings and not density measurements Adjunct for Temperature and Pressure Volume Correction 1.3 The initial hydrometer readings determined shall be Factors for Generalized Crude Oils, Refined Products, and recorded before performing any calculations Then the calcu- Lubricating Oils: API MPMS Chapter 11.1 lations required in Section 9 shall be performed and docu- D1298 Test Method for Density, Relative Density, or API mented before using the final result in a subsequent calculation Gravity of Crude Petroleum and Liquid Petroleum Prod- procedure (measurement ticket calculation, meter factor ucts by Hydrometer Method calculation, or base prover volume determination) D6822 Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Prod- 1.4 The values stated in inch-pound units are to be regarded ucts by Thermohydrometer Method as standard The values given in parentheses are mathematical D7962 Practice for Determination of Minimum Immersion Depth and Assessment of Temperature Sensor Measure- 1 This test method is under the jurisdiction of ASTM Committee D02 on ment Drift Petroleum Products, Liquid Fuels, and Lubricants and the API Committee on D8164 Guide for Digital Contact Thermometers for Petro- Petroleum Measurement, and is the direct responsibility of Subcommittee D02.02 leum Products, Liquid Fuels, and Lubricant Testing /COMQ, the joint ASTM-API Committee on Hydrocarbon Measurement for E1 Specification for ASTM Liquid-in-Glass Thermometers Custody Transfer (Joint ASTM-API) E77 Test Method for Inspection and Verification of Ther- mometers Current edition approved Dec 1, 2022 Published February 2023 Originally approved in 1928 Last previous edition approved in 2019 as D287–12b (2019) 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or DOI: 10.1520/D0287-22 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 1 D287 − 22 E100 Specification for ASTM Hydrometers 3.1.3 observed values, n—values observed at temperatures E126 Test Method for Inspection, Calibration, and Verifica- other than the specified reference temperature; these values are only hydrometer readings and not density, relative density, or tion of ASTM Hydrometers API gravity at those other temperatures E344 Terminology Relating to Thermometry and Hydrom- 3.1.4 specific gravity, n—historical term, no longer used, etry which has been replaced by relative density E2251 Specification for Liquid-in-Glass ASTM Thermom- 3.2 Acronyms: eters with Low-Hazard Precision Liquids 3.2.1 PRT—platinum resistance temperature device E2877 Guide for Digital Contact Thermometers 3.2.1.1 Discussion—While there may be other types of 2.2 API Standards:3 RTDs available, for Custody Transfer operations in conjunc- MPMS Chapter 9.1 Test Method for Density, Relative tion with other standards organizations Platinum RTDs have been standardized on for their accuracy and discrimination Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method (ASTM Test 4 Summary of Test Method Method D1298) MPMSChapter 9.3 Test Method for Density, Relative 4.1 This test method is based on the principle that the Density, and API Gravity of Crude Petroleum and Liquid gravity of a liquid varies directly with the depth of immersion Petroleum Products by Thermohydrometer Method of a body floating in it The floating body, which is graduated (ASTM Test Method D6822) by API gravity units in this test method, is called an API MPMS Chapter 11.1 Temperature and Pressure Volume Cor- hydrometer rection Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils (Adjunct to ASTM D1250) 4.2 The API gravity is read by observing the freely floating ASTM hydrometer (calibrated for API gravity) and noting the 2.3 ASTM Adjuncts: graduation nearest to the apparent intersection of the horizontal Adjunct to D1250 Standard Guide for the Use of the Joint plane surface of the liquid with the vertical scale of the hydrometer, after temperature equilibrium has been reached API and ASTM Adjunct for Temperature and Pressure The temperature of the sample shall be read from a separate Volume Correction Factors for Generalized Crude Oils, accurate ASTM thermometer placed in the sample, which Refined Products, and Lubricating Oils: API MPMS Chap- meets either Specifications E1 or E2251 requirements or ter 11.1)4 ASTM Digital Contact Thermometers, which meet Guide E2877 requirements The temperature determination device, be 3 Terminology it the bulb of a ASTM Thermometer (Specifications E1 or E2251) or a sensor of a Digital Contact Thermometer (Guide 3.1 Definitions: E2877) shall be placed at the same elevation (within the stated 3.1.1 API gravity, n—a special function of relative density tolerances) as the hydrometer bulb 60/60 °F (15.56/15.56 °C), represented by: NOTE 1—Through various testings that Subcommittee D02.02 (Joint °API 5 @141.5/~relative density 60/60 °F!# 2 131.5 (1) ASTM/API Subcommittee) measurement committee and others have conducted, it has been determined that temperature stratifications do exist No statement of reference temperature is required, since vertically from top to bottom of a hydrocarbon container as well as across 60 °F is included in the definition the diameter of the container Therefore, as temperature affects the viscosity as well as the fluid density, the buoyancy of the hydrometer 3.1.2 hydrometer reading, n—the point on the hydrometer floating in the liquid is therefore affected, clarifying procedures have been scale at which the surface of the liquid cuts the scale added to the Procedure section 3.1.2.1 Discussion—In practice for transparent fluids this 4.3 The observed hydrometer reading is corrected for the can be readily determined by aligning the surface of the liquid meniscus effect, the thermal glass expansion effect on the on both sides of the hydrometer and reading the Hydrometer hydrometer, alternate calibration temperature effects and re- scale where these surface readings cut the scale (Hydrometer duced to the reference temperature by means of the petroleum Reading – Observed) For nontransparent fluids the point at measurement tables If necessary, the hydrometer cylinder and which the liquid surface cuts the Hydrometer scale cannot be its contents are placed in a constant temperature bath to avoid determined directly and requires a correction (Meniscus Cor- excessive temperature variation during the test rection) The value represented by the point (Meniscus Read- ing) at which the liquid sample rises above the main surface of 5 Significance and Use the liquid subtracted from the value represented by where the main surface of the liquid cuts the Hydrometer scale is the 5.1 Accurate determination of the gravity of petroleum and amount of the correction or Meniscus correction This menis- its products is necessary for the conversion of measured cus correction is documented and then subtracted from the volumes to volumes at the standard temperature of 60 °F value represented by the Meniscus Reading to yield the (15.56 °C) Hydrometer Reading corrected for the Meniscus (Hydrometer Reading – Observed, Meniscus Corrected) 5.2 This procedure is most suitable for determining the API gravity of low viscosity transparent liquids This test method 3 Available from American Petroleum Institute (API), 200 Massachusetts Ave can also be used for viscous liquids by allowing sufficient time NW, Suite 1100, Washington, DC 20001, http://www.api.org for the hydrometer to reach temperature equilibrium, and for 4 Available from ASTM International Headquarters Order Adjunct No ADJD1250-A1A2-E-PDF Original adjunct produced in 1983 2 D287 − 22 opaque liquids by employing a suitable meniscus correction TABLE 2 Available Hydrometers Scaled, Degrees API (Low Additionally for both transparent and opaque fluids the read- Hazardous Liquid Type) ings shall be corrected for the thermal glass expansion effect before correcting to the reference temperature ASTM Type API Range, Each Unit Scale Hydrometer deg 5.3 When used in connection with bulk oil measurements, Designation thermo 12 Division Error volume correction errors are minimized by observing the thermo –1 to 11 12 hydrometer reading at a temperature as close to reference 52HL thermo 9 to 21 12 0.1 0.1 temperature as feasible 52HL thermo 19 to 31 12 0.1 0.1 53HL thermo 29 to 41 12 0.1 0.1 5.4 Gravity is a factor governing the quality of crude oils 54HL thermo 39 to 51 12 0.1 0.1 However, the gravity of a petroleum product is an uncertain 55HL thermo 49 to 61 12 0.1 0.1 indication of its quality Correlated with other properties, 56HL thermo 59 to 71 12 0.1 0.1 gravity can be used to give approximate hydrocarbon compo- 57HL thermo 69 to 81 12 0.1 0.1 sition and heat of combustion 58HL thermo 79 to 91 12 0.1 0.1 59HL 89 to 101 0.1 0.1 5.5 Gravity is an important quality indicator for automotive, 60HL 0.1 0.1 aviation and marine fuels, where it affects storage, handling and combustion liquid-in-glass thermometers The stated repeatability and re- producibility values are not applicable if alternate fluids are 6 Apparatus used in the liquid-in-glass thermometers 6.1 Hydrometers, of glass, graduated in degrees API as 6.2.3 Digital Temperature Sensors—Digital Contact Ther- listed in Table 1 and conforming to Specification E100 or as mometers of the PRT style shall meet the requirements of listed in Table 2 and conforming to Specification E2251 Guide E2877 and may be used instead of glass thermometers with the following exceptions: 6.1.1 The user should ascertain that the instruments used for this method conform to the requirements set out above with 6.2.3.1 Thermocouples shall not be used respect to materials, dimensions, and scale errors In cases 6.2.3.2 Thermistors shall not be used where the instrument is provided with a calibration certificate traceable to a NMI (National Metrology Institute), the instru- 6.3 Hydrometer Cylinder, transparent material (see 6.3.2) ment is classed as certified and the appropriate corrections for The inside diameter of the cylinder shall be at least 0.25 in the meniscus effect, the thermal glass expansion effect, and (6.35 mm) greater (see A in Fig 1) than the outside diameter of alternative calibration temperature effects shall be applied to the hydrometer body and the temperature measuring device the observed readings prior to corrections Instruments that plus the separation interval specified in Fig 1 and the height satisfy the requirements of this test method, but are not shall be such that the appropriate hydrometer floats in the test provided with a recognized calibration certificate, are classed portion with at least 1 in (25 mm) clearance between the as uncertified bottom of the hydrometer and the bottom of the cylinder, under all densities and temperatures Ensure that the hydrometer 6.2 Temperature Determination: cylinder is cleaned after each use to ensure that no contami- 6.2.1 Thermometers (Glass), having a range from −5 °F to nants remain +215 °F and conforming to the requirements for Thermometer 12F as prescribed in Specification E1 6.3.1 When using separate hydrometer (or thermohydrom- eter) and temperature measuring devices, care shall be exer- NOTE 2—The ASTM Gravity Thermometer 12F has 0.5 °F subdivisions cised to ensure that neither interfere with each other and that and allowable 60.25 °F scale error and is suitable for use in determining they are not affected by external temperature effects The temperature of bulk crude oil volumes, such as lease production tanks minimum separation distances as shown in Fig 1 shall be Additional thermometers conform to Specification E1 standard or Speci- required These separation distances are a function of the fication E2251 standard having a narrower range than the 12F or S12F diameters of the measuring devices and the minimum distance Thermometers may also be used, if they have similar performance from the sides of the measuring chamber to minimize external characteristics thermal effects 6.2.2 Alternate liquid measuring device (Thermometer where: S12F) conforming to the requirements prescribed in Specifi- cation E2251 may be used, provided that the total uncertainty A = minimum separation interval specified in 6.3 between of the calibrated system is no greater than when using the inside diameter of hydrometer cylinder and the sum of the OD of the hydrometer body plus the OD of TABLE 1 Available Hydrometers Scaled, Degrees API temperature measuring device plus the minimum sepa- ration interval between devices of 0.25 in (6.35 mm), Designation Type API Range, deg Scale see Fig 1, and Series Total Each Unit Division Error B = minimum separation interval between measuring de- 1H to 10H long plain −1 to 101 12 0.1 0.1 vices of 0.5 in (12.7 mm) 21H to 40H short plain 0 to 101 41H to 45 H thermo 6 0.1 0.2 6.3.2 Hydrometer cylinders constructed of transparent ma- 51H to 60H thermo 15 to 51 terials shall be resistant to discoloration or attack by the 71H to 74H thermo −1 to 101 8 0.1 0.1 petroleum or petroleum product samples and shall not affect −1 to 41 the material being tested They shall not become opaque under 12 0.1 0.1 prolonged exposure to sunlight If the opacity prevents the 12 0.1 0.1 3 D287 − 22 FIG 1 Separation Intervals (minimum requirements) between Devices and Hydrometer Cylinder observation of both devices then the hydrometer cylinder shall sample physical properties to ensure that the devices can be replaced before continuing with the test function properly For example, with highly volatile samples being measured in an open container the light ends may 6.3.3 The minimum separation intervals specified is to evaporate while the devices are reaching temperature equilib- prevent any capillary action between devices and to ensure that rium This is a function of ambient temperature as well as fluid external temperature effects are minimized on the values temperature and composition Conversely, if the fluid is too determined for density and temperature viscous (thick) the hydrometer may not float freely, which is a requirement for a buoyance device 7 Temperature of Test (Limiting Conditions of Test) 8 Procedure 7.1 The gravity determined by the hydrometer method is most accurate at or near the standard temperature of 60 °F 8.1 For referee testing, use the long plain form of hydrom- (15.56 °C) Use this or any other temperature between 0 °F and eter (1H to 10H) For field testing, the thermohydrometer 195 °F (–18 °C and + 90 °C) for the test, so far as it is method in Test Method D6822 (API MPMS Chapter 9.3) is the consistent with the type of sample and necessary limiting preferred method However, if the user desires to use a conditions shown in Table 3 liquid-in-glass thermometer with low-hazard glass precision fluid as specified in Specification E2251 or a Digital Contact 7.2 The purpose of Table 3 is to clarify what actions are Thermometer as specified in Guide E2877 and 6.2.3, the user required to ensure that the sample does not change its physical makeup during the testing period or modifications to the TABLE 3 Limiting Conditions and Testing Temperatures Sample Type Gravity Limits Initial Boiling Point Other Limits Test Temperature Highly volatile Limits Moderately volatile Moderately volatile and viscous lighter than 70° API below 250 °F (120 °C) Viscosity too high at Cool to 35 °F (2 °C) or lower in original closed heavier than 70° API below 250 °F (120 °C) 65 °F (18 °C) container Nonvolatile heavier than 70° API above 250 °F (120 °C) Mixtures of nonpetroleum products or heavier than 70° API Cool to 65 °F (18 °C) or lower in original closed container essentially pure hydrocarbons Heat to minimum temperature for sufficient fluidity Any temperature between 0 °F and 195 °F (−18 °C and 90 °C) as convenient 60 °F ± 0.25 °F (15.56 °C ± 0.1 °C) 4 D287 − 22 can use Test Method D6822 (API MPMS Chapter 9.3) with a bubbles to come to the surface This is particularly necessary in modified procedure as detailed in 8.11 of this test method the case of the more viscous samples 8.1.1 As shown in Table 1 and Table 2, the user has access 8.7 Lower the temperature measuring device slowly into the to hydrometers covering various ranges of API gravity The sample, in close proximity to the hydrometer installed in 8.6 user should select a hydrometer which results in the liquid making sure that neither touch, nor come in contact with the interface cutting the hydrometer stem in the center third of the side walls of the sample cylinder Refer to Fig 2a and Fig 2b range The hydrometer should not be used when the liquid and Fig 3a and Fig 3b The temperature measuring device interface cuts the scale in the bottom two API gravity values or may also be used to cautiously and slowly stir the sample at the top two API gravity values instead of the hydrometer, to minimize stratification 8.1.2 When using digital temperature devices the user shall 8.7.1 The hydrometer is a buoyancy device, its performance utilize only intrinsically rated temperature devices that con- or where it floats is dependent on the temperature of the fluid form to the appropriate standard around the point of buoyancy Therefore, it is essential that the sample temperature be taken as close to this point of buoyancy NOTE 3—In practice whether in a lab or field environment this test In practice with opaque samples this point can be difficult to method is used in a potentially hazardous environment (that is, explosive) determine However, it can be estimated from knowing the and as these devices are electrically powered which could possibly lengths of the various instruments and then estimating their produce a spark, potentially resulting in an explosion/fire All companies relative positions generally have Engineering and Operating standards that refer to NFPA (National Fire Protection Association) and NEC (National Electrical 8.8 When the hydrometer has come to rest, floating freely, Code) codes that detail the requirements for the use of electrical devices and the temperature of the sample is constant to within 0.2 °F in classified areas These company requirements should take precedence (0.1 °C), read and record the hydrometer reading to the nearest scale division The correct reading is that point on the 8.2 Prior to lowering the selected hydrometer and/or tem- hydrometer scale at which the surface of the liquid cuts the perature determination instrument into the sample perform the scale Determine this point by placing the eye slightly below Equipment Validation enumerated in Annex A1 the level of the liquid and slowly raising it until the surface, first seen as a distorted ellipse, appears to become a straight 8.3 Verify that the selected density and/or temperature line cutting the hydrometer scale See Fig 4 determination instruments conform to the requirements of Annex A2 8.9 To make a reading with nontransparent liquids, observe the point on the hydrometer scale to which the sample rises 8.4 Adjust the temperature of the sample in accordance with above its main surface, placing the eye slightly above the plane Table 3 For field testing, test temperatures other than those surface of the liquid This reading requires a correction listed in Table 3 may be used The hydrometer cylinder shall be Determine this correction (meniscus correction) for the par- approximately the same temperature as the sample to be tested ticular hydrometer in use by observing the height above the 8.5 Transfer the sample into the clean hydrometer cylinder where: without splashing, so as to avoid the formation of air bubbles A = separation interval specified in 6.3 and Fig 1, and to reduce to a minimum the evaporation of the lower B = separation interval specified in 6.3 and Fig 1, and boiling constituents of the more volatile samples (Warning— C = relative vertical alignment between the density and Samples may be extremely flammable Vapors may cause flash fire.) For the more volatile samples, transfer to the hydrometer temperature measuring devices (the bottom of the sens- cylinder by siphoning (Do not start the siphon by mouth.) ing portion of the temperature measuring device should Remove any air bubbles formed, after they have collected on be within 60.5 in (612.5 mm) and not more than the surface of the sample, by touching them with a piece of 61.0 in (625 mm) of the bottom of the density sensor) clean filter paper or other suitable means before inserting the hydrometer For field testing, the gravity measurement is FIG 2 a Hydrometer and Liquid-in-Glass Thermometer Placement directly made in the sampling core thief or hydrometer (Typical) 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 5 D287 − 22 where: where: A = separation interval specified in 6.3 and Fig 1, A = separation interval specified in 6.3 and Fig 1, B = separation interval specified in 6.3 and Fig 1, and B = separation interval specified in 6.3 and Fig 1, and C = relative vertical alignment between the density and C = relative vertical alignment between the density and temperature measuring devices (the bottom of the sens- temperature measuring devices (the bottom of the sens- ing portion of the temperature measuring device should ing portion of the temperature measuring device should be within 60.5 in (612.5 mm) and not more than be within 60.5 in (612.5 mm) and not more than 61.0 in (625 mm) of the bottom of the density sensor) 61.0 in (625 mm) of the bottom of the density sensor) FIG 2 b Thermohydrometer and Liquid-in-Glass Thermometer FIG 3 b Thermohydrometer and Digital Contact Thermometer Placement (Typical) (continued) Placement (Typical) (continued) where: A = separation interval specified in 6.3 and Fig 1, B = separation interval specified in 6.3 and Fig 1, and C = relative vertical alignment between the density and temperature measuring devices (the bottom of the sens- ing portion of the temperature measuring 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) main surface of the liquid to which the sample rises on the FIG 4 Hydrometer Scale Reading for Transparent Liquids hydrometer scale when the hydrometer in question is immersed (Typical) in a transparent liquid having a surface tension similar to that of a sample under test See Fig 5 8.9.2 When gravity readings have been observed on opaque liquids using the procedure given in 8.9, subtract the meniscus 8.9.1 Record the observed hydrometer scale readings to the correction from the hydrometer reading observed and record nearest 0.1° API for transparent liquids the meniscus corrected hydrometer scale reading to the nearest 0.1° API 6 D287 − 22 9 Calculation 9.1 Apply any relevant thermometer corrections to the temperature reading observed in 8.10 and record the average of those two temperatures to the nearest 1 °F FIG 5 Hydrometer Scale Reading for Opaque Fluids (Typical) 9.2 Application of the glass thermal expansion correction depends upon what edition of Adjunct to D1250 Standard NOTE 4—The meniscus correction for a particular hydrometer in use is Guide for the Use of the Joint API and ASTM Adjunct for determined by observing the maximum height above the principal surface Temperature and Pressure Volume Correction Factors for of the liquid to which liquid rises on the hydrometer scale when the Generalized Crude Oils, Refined Products, and Lubricating hydrometer in question is immersed in a transparent liquid having a Oils (API MPMS Chapter 11.1) will be used to calculate the surface tension similar to that of the sample under test base density 8.10 Observe the temperature of the sample immediately 9.2.1 The 1980 version of the Adjunct to D1250 Guide for before and after the observation of the gravity, the liquid in the Petroleum Measurement Tables (API MPMS Chapter 11.1) has cylinder being thoroughly but cautiously stirred with the the hydrometer glass thermal expansion correction included thermometer (Note 5), and the whole of the temperature thread Input into the Adjunct to D1250 Standard Guide for the Use of being immersed Should these temperature readings differ by the Joint API and ASTM Adjunct for Temperature and Pressure more than 1 °F (0.5 °C), repeat the temperature and gravity Volume Correction Factors for Generalized Crude Oils, Re- observations when the temperature of the sample has become fined Products, and Lubricating Oils (API MPMS Chapter more stable Record the mean of the thermometer reading 11.1) software (see API MPMS Ch 11.1.1.3 paragraphs 5 and before and after the final hydrometer reading, to the nearest 6) requires the Hydrometer Reading – Observed or Hydrometer 1 °F, as the temperature of the test Reading – Observed, Meniscus Corrected in API units from 8.9.1 or 8.9.2, observed temperature of the sample, and the 8.11 When using a separate temperature measuring device built-in hydrometer glass thermal correction switch set to “on” such as a liquid-in-glass thermometer; a liquid-in-glass ther- (0) or “off” (1) It will return API @ 60 °F mometer with low-hazard precision liquid or a digital contact thermometer they shall be placed in the sample measurement 9.2.2 The 2004 version of the Adjunct to D1250 Guide for cylinder as shown in Fig 2a and Fig 2b as well as Fig 3a and Petroleum Measurement Tables (API MPMS Chapter 11.1) Fig 3b does not include the hydrometer glass thermal expansion correction, so that correction must be made before entering the NOTE 5—When only thermohydrometers are used, stir the sample by Adjunct to D1250 Standard Guide for the Use of the Joint API carefully moving the thermohydrometer in a side to side motion, without and ASTM Adjunct for Temperature and Pressure Volume immersing the thermohydrometer any lower into sample It is satisfactory Correction Factors for Generalized Crude Oils, Refined in this case to read the thermometer scale of the thermohydrometer after Products, and Lubricating Oils (API MPMS Chapter 11.1) the hydrometer reading has been observed Read the thermometer to the software Depending on the specific end use of the calculation nearest 1 °F (0.5 °C) If using a separate device to measure temperature, results, the final value may be left rounded or unrounded See use the temperature measuring device to stir the sample and read 9.3 according to 8.10 9.3 The following steps are required to implement 9.2.2: Step 1 Convert the meniscus corrected hydrometer scale reading to density in kg/m3 using Eq 2 Hydrometer Scale Conversion to Density Reading Units 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 (Tb) 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/m3 from Step 1 by HYC from Step 2 to obtain the glass expansion corrected hydrometer reading kg/m3HYC 5 kg/m3*HYC (4) 7 D287 − 22 Step 4a Convert the hydrometer reading in density (kg/ 10.2 Report the final value as API gravity, at the reference m HYC 3 ) from Step 3 to a R.D (relative density) hydrometer temperature (nearest whole degree °F), to the nearest 0.1° API reading 10.3 The reporting values have no precision or bias deter- NOTE 6—The current C source code, compiled dll and Excel Add-in has mination It is up to the user to determine whether this test an omission and cannot use a kg/m3 call with degree F method provides results of sufficient accuracy for the intended purpose R.D 5 kg/m HYC 3 /999.016 (5) 10.4 If the hydrometer readings are being used as an input to Step 4b Input R.D and degree F into section 11.1.6.2 of the a calculation process intended to return a volume correction Adjunct to D1250-04 Guide for Petroleum Measurement factor for use in ticket or meter proving calculations, stop the Tables (API MPMS Chapter 11.1-2004) which returns R.D @ calculation process identified above at Step 3 (if the density 60 °F value is desired at flowing conditions) or Step 4 (if the density value is desired at base density conditions) and input the results NOTE 7—Pressure will have to be atmospheric gauge, or 0 psig as the into the calculation process Adjunct to D1250 Standard Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure Volume Correction Factors for 10.5 Certified hydrometers traceable to a NMI (National Generalized Crude Oils, Refined Products, and Lubricating Oils (API Metrology Institute), report the output density as ‘Density in MPMS Chapter 11.1) values are only valid at atmospheric pressure Vacuo’ Step 4c Convert the calculated R.D value @ 60 °F to a 11 Precision and Bias calculated API Gravity @ 60 °F using Eq 6 11.1 The precision of this test method as obtained by API Gravity 5 ~141.5/R.D.! 2 131.5 (6) statistical examination of interlaboratory test results is as follows: 9.4 Future versions of the Adjunct to D1250 Standard Guide for the Use of the Joint API and ASTM Adjunct for Tempera- 11.1.1 Repeatability—The difference between successive ture and Pressure Volume Correction Factors for Generalized test results obtained by the same operator with the same Crude Oils, Refined Products, and Lubricating Oils (API apparatus under constant operating conditions on identical test MPMS Chapter 11.1) code will be corrected so that it can material, would in the long run, in the normal and correct accept any combination of input units and return any combi- operation of the test method, exceed 0.2° API only in one case nation of output units When available, the Adjunct to D1250 in twenty Standard Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure Volume Correction 11.1.2 Reproducibility—The difference between two single Factors for Generalized Crude Oils, Refined Products, and and independent results, obtained by different operators, work- Lubricating Oils (API MPMS Chapter 11.1) code can be ing in different laboratories on identical test material, would in accessed directly from Step 3 and return API Gravity @ 60 °F, the long run, in the normal and correct operation of the test R.D @ 60 °F, and kg/m3 at any selected base temperature method, exceed 0.5° API only in one case in twenty Sample: Example 1 (Eq 2) NOTE 8—The precision for this test method was not obtained in Observed Temperature: Crude Oil (Eq 3) accordance with RR:D02-1007 Observed Hydrometer Reading: 77 °F (Eq 4) Observed Pressure: 33.2 API Gravity (Eq 5) NOTE 9—The precision for this test method only applies to measure- Base Temperature: 0 psig ments made with a liquid-in-glass thermometer Step 1: 60 °F (Eq 6) Step 2: 858.292434730 (Eq 6) NOTE 10—This precision statement applies only to measurements made Step 3: 0.999780948 at temperatures differing from 60 °F (15.56 °C) by less than 18 °F (10 °C) Step 4a: 858.104424227 Step 4b: 0.858949631 11.2 Bias—Bias for this test method has not been deter- Step 4c.1: 0.865678279 mined Step 4c.2: 31.955643312 unrounded 32.0 °API rounded 12 Keywords 10 Report 12.1 API gravity; crude petroleum; digital contact thermom- eter; hydrometer; thermohydrometer; thermometer 10.1 Report the corrected hydrometer reading as degrees API (°API) or as API Gravity 8 D287 − 22 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- (e) The paper scale within the thermohydrometer stem sity and temperature measuring instruments being used for the shall contain an information label that documents the ASTM test shall be verified that they are “Fit for Use at Time of Test” hydrometer designation, units of density, and a serial number as delineated by the following procedures The specific proce- dures the user shall use will be dependent on the specific test (f) The thermohydrometer shall contain a scale slippage instruments being used for that test indicator and shall be positioned at the proper position relative to the scale This is typically the whole unit value graduation A1.2 These verifications shall be performed on each test mark for the upper range the instrument is designed for instrument immediately prior to each test being performed (3) If any of the items in A1.4.1.2(2) do not meet the A1.3 Each test instrument shall be in a clean condition prior defined criteria, the instrument shall no longer be used and to the equipment validation so that each component of the Test shall be replaced Instrument can be validated A1.4.2 Temperature Instruments: A1.4 Equipment Validation Procedures A1.4.2.1 Liquid-in-Glass Type Instruments: A1.4.1 Density Instruments: (1) Ensure that the liquid-in-glass temperature instrument A1.4.1.1 Hydrometers: scale range selected for the analytical test covers the expected (1) Ensure that the hydrometer scale range selected for the temperature reading analytical test covers the expected density reading (2) Inspect the liquid-in-glass temperature instrument to (2) Inspect the hydrometer and ensure that it meets the ensure it meets the following requirements: following requirements: (a) The temperature instrument glass shall contain no (a) The hydrometer glass shall contain no cracks, fissures, cracks, fissures, deep scratches, rough areas, or other obvious damage deep scratches, rough areas, or other obvious damage (b) The ballast at the bottom of the hydrometer shall (b) The temperature glass instrument shall contain per- manent markings that document the ASTM temperature instru- contain no loose components ment designation and the instrument’s serial number (c) The ballast at the bottom of the hydrometer shall be (c) The liquid column is continuous from the fluid reser- firmly affixed to glass envelope of the test instrument voir to the indicated temperature (d) The paper scale within the hydrometer stem shall be (d) Ensure that the temperature scale and its graduation straight and without twist markings are intact on the instrument (e) The paper scale within the hydrometer stem shall (3) If any of the items in A1.4.2.1(2) do not meet the contain an information label that documents the ASTM hy- defined criteria, the instrument shall no longer be used and drometer designation, units of density, and a serial number shall be replaced, with the exception of item A1.4.2.1(2)(c) (f) The hydrometer shall contain a scale slippage indica- (4) If the liquid column is non-continuous, the temperature tor and shall be positioned at the proper position relative to the instrument shall be placed in a liquid bath and the temperature scale This is typically the whole unit value graduation mark of the bath increased until it causes the liquid column to expand for the upper range the instrument is designed for into the upper expansion area After this occurs, remove the temperature instrument from the liquid bath and cool the (3) If any of the items in A1.4.1.1(2) do not meet the instrument down to ambient temperature Reverify that the defined criteria, the instrument shall no longer be used and liquid column is now continuous shall be replaced (5) If the liquid column is now continuous verify that the A1.4.1.2 Thermohydrometers: instrument still indicates the correct temperature in accordance (1) Ensure that the thermohydrometer scale range selected wiAnnex A2th If the column is non-continuous the instrument shall not be used, perform the procedure in A1.4.2.1(4) again for the analytical test covers the expected density reading to try to re-unite the column and then re-verify per A1.4.2.1(5) (2) Inspect the thermohydrometer and ensure that it meets A1.4.2.2 Digital Contact Thermometer: the following requirements: (1) Inspect the Digital Contact Thermometer to ensure it (a) The thermohydrometer glass shall contain no cracks, meets the following requirements: fissures, deep scratches, rough areas, or other obvious damage (a) The temperature instrument sensor shall be a PRT (b) The ballast at the bottom of the thermohydrometer style meeting the requirements of Guide E2877 shall contain no loose components (b) The temperature instrument shall meet the require- (c) The ballast at the bottom of the thermohydrometer ments of 6.2.3 of this test method shall be firmly affixed to glass envelope of the test instrument (c) Inspect the temperature instrument and ensure that all (d) The paper scale within the thermohydrometer stem components meet all mechanical and electrical requirements shall be straight and without twist 9 D287 − 22 (d) Perform an operational performance check in accor- (d) Verify that the display(s) are legible dance with the manufacturer’s requirements: (e) Verify that when turned on the temperature reading is indicating a change and the change is indicating in the correct (1) Note—For digital contact thermometers being used direction: multiple times in a short period of time, such as determining (1) The comparison device for the operational perfor- the temperature reading of multiple samples in a laboratory mance check could be a liquid-in-glass thermometer; a pocket over a very short interval (an hour or less) this step may be dial thermometer; an ambient air reading from a local source or skipped once it is performed once other suitable source (2) This check is intended to verify that the instrument is (2) However, if an interval of 60 min or more is experi- working properly and not that it is measuring temperature enced between analytical tests then this performance check is accurately required prior to any further testing (e) Verify that the temperature instrument shall have been calibrated in accordance with Annex A3 (3) Operational Performance Check: (2) The digital contact thermometer shall be calibrated in (a) Verify that the device is in good working order accordance with Annex A3 if any of the requirements in (b) Verify that there is no mechanical damage to the A1.4.2.2 are not met prior to any use instrument case body, temperature sensor, or the connecting wiring (c) Verify that the battery voltage is in the manufacturer’s recommended operating range A2 PERFORMANCE VERIFICATION OF DENSITY AND TEMPERATURE MEASURING INSTRUMENTS A2.1 All density and temperature measuring instruments A2.3.1.1 Test Method E126 shall be used as the reference shall be verified on a periodic schedule, which depends on the standard (for the calibration of the Primary Verification De- frequency of use vice) for the verification of density instruments A2.2 Verification Process—Verification is a process A2.3.1.2 Density instruments shall be verified at two test whereby the working instrument is compared to another similar points (approximately lower half and upper half on the device with a higher accuracy (lower uncertainty) This device hydrometer scale) on the density scale Test points shall be is typically referred to as a “Primary Verification Device or chosen to bracket the range of use Master Device” A2.3.1.3 For routine verification work, one may use a A2.2.1 The Primary Verification Device shall have been standard hydrometer as specified in Section 6 of Test Method calibrated using standards traceable to a NMI (National Me- E126 and a reference fluid with similar surface tension and trology Institute) and calibrated in accordance with the appro- density of the liquids the hydrometer is intended to be used, see priate sections of Test Method E126 Table 2 in Test Method E126 for guidance NOTE A2.1—In the United States, the NMI is the National Institute of A2.3.2 Temperature Instruments: Standards and Technology (NIST) and in Canada it is Measurement A2.3.2.1 Test Method E77 shall be used as the reference Canada Many companies which supply hydrometers, thermometers to the standard for the verification of temperature instruments industry have the capability to provide equipment with NMI traceability (1) Secondary standard thermometers as specified in 5.5 of A2.2.2 The calibration of the Primary Verification Device Test Method E77 are more suitable for routine work shall be performed on an annual basis (2) Alternatively the user may also use a primary standard A2.2.3 Verifications shall be performed using a liquid bath thermometer as specified in 5.4 of Test Method E77 both for density and temperature instruments A2.3.2.2 Temperature instruments shall be verified at two or A2.2.3.1 A Primary Verification Device used with a test/dry more test points on the temperature scale Test points shall be block may be substituted for a liquid bath for temperature chosen to bracket the range of use instruments, provided that it facilitates the ability to determine the temperature readings of both the Primary Verification A2.4 Frequency of Verification: Device and the working instrument without moving the instru- ments within the test block A2.4.1 Density Instruments: A2.4.1.1 Hydrometers and thermohydrometers should be A2.3 Verification Test Points: verified monthly (at a minimum they shall be verified quar- terly) for frequently used instruments (used four or more times A2.3.1 Density Instruments: 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 10 D287 − 22 four months) for infrequently used instruments (used three A2.4.2 Temperature Instruments: times or less in a seven day period) A2.4.2.1 Temperature instruments shall be verified monthly A2.4.1.3 The preferred method is a comparison in a liquid (at a minimum; weekly verifications would be optimal) for bath, using a fluid with a similar surface tension and density for frequently used instruments (used four or more times in a seven which the hydrometer is intended to be used See Test Method day period) E126 for guidance A2.4.2.2 Temperature instruments shall be verified bi- A2.4.1.4 The verification test is a comparison of the stan- monthly (at a minimum: every four months) for infrequently dard hydrometer reading (which has been calibrated in accor- used instruments (used three times or less in a seven day dance with Test Method E126 guidelines) to the reading of the period) working hydrometer within one (1) scale division (0.1°API) A3 CERTIFICATION CALIBRATION OF DENSITY AND TEMPERATURE MEASURING INSTRUMENTS A3.1 All density and temperature measuring instruments A3.2.1.1 Test Method E126 shall be used as the reference shall be calibrated on a periodic schedule, which depends on standard guide for the calibration of density instruments the frequency of use A3.2.1.2 Density instruments shall be calibrated at three test A3.1.1 Calibration Process—Calibration is a process points (approximately low, medium, and high on the hydrom- whereby the primary verification device (may also be called eter scale) on the density scale Test points shall be chosen to master device) is subjected to a set of operations that establish, bracket the range of use under specified conditions, the relationship between the values indicated by a measuring device and the corresponding known A3.2.2 Temperature Instruments: values indicated when using a suitable measuring standard, A3.2.2.1 Test Method E77 shall be used as the reference traceable to a NMI, which is then applied to adjust the values standard guide for the calibration of temperature liquid-in-glass determined by the measuring device instruments A3.2.2.2 Guide E2877 and Test Method E77 shall be used A3.1.2 Certified—The process and documentation whereby as the reference standard guide for the calibration of Tempera- a device or material is accepted as a reference standard, ture Digital Contact Thermometers accurate within prescribed limits, and traceable to a NMI A3.2.2.3 Temperature instruments shall be verified at two or more test points on the temperature scale Test points shall be A3.1.3 The calibration shall be performed on an annual chosen to bracket the range of use basis: A3.3 Handling, Shipping, and Documentation of Density A3.1.3.1 If the calibrated instrument is not placed into and Temperature Measuring Instruments: service immediately after the user receives it back from the calibration laboratory, the calibration remains in effect for one A3.3.1 All density and temperature measuring instruments year from the original calibration date on the calibration shall be securely packaged whether being shipped from the certificate calibration laboratory or to it to prevent any damage from occurring during the shipping process A3.1.3.2 Once the calibrated instrument is placed into service, providing it is done within the one year grace period A3.3.2 All calibrated instruments shall be supplied with a after original calibration or any subsequent re-calibrations, the calibration certificate that provides at a minimum the following annual calibration time period begins information: A3.1.3.3 Once an instrument exceeds the one year calibra- A3.3.2.1 ASTM number, tion grace period, without being placed in service, the calibra- A3.3.2.2 Range of instrument over which it was calibrated, tion certificate is void and the instrument shall be re-calibrated A3.3.2.3 Serial number, A3.3.2.4 Name of manufacturer, A3.1.3.4 These instruments should be properly stored in a A3.3.2.5 Name of calibration laboratory climate-controlled space and not exposed to extreme weather A3.3.2.6 Calibration certified date, and Devices should also be kept in a controlled and secure A3.3.2.7 Calibration results/documentation in accordance environment to maintain the integrity and accuracy of the with the applicable calibration protocol device NOTE A3.1—Column separation may occur during the shipping process Warning—Instruments which will be calibrated by defini- which does not affect the calibration or certification of the instrument If tion have a shelf life and the calibration and certification of the user experiences this then follow the procedure in Annex A1, these instruments is typically preformed when ordered Ad- A1.4.1.1.1 of Test Method D287, to rejoin column, this does not affect the equate lead time should be allowed when requesting a cali- overall certification brated or certified instrument A3.2 Calibration Test Points A3.2.1 Density Instruments: 11 D287 − 22 SUMMARY OF CHANGES Subcommittee D02.02 has identified the location of selected changes to this standard since the last issue (D287 – 12b (2019)) that may impact the use of this standard (Approved Dec 1, 2022.) (1) Revised title (6) Added definitions for observed values and PRT to Section (2) Revised subsections 1.1, 1.2, 4.2, 4.3, 6.1, 6.1.1, 6.2 (and 3 subsections), 6.3, 6.3.2, 8.1, 8.5, 8.8, 8.9, 8.10, 9.2.1, 9.2.2, (7) Added Note 1, Note 2, Note 3, Note 4, and Note 9, and 10.2, and 10.5 renumbered subsequent (3) Added subsections 6.2.3, 6.3.1, 6.3.3, 7.2, 8.1.1, 8.1.2, 8.2, (8) Deleted former Note 3 and renumbered subsequent 8.3, 8.7, 8.7.1, 8.9.1, 8.9.2, and 8.11 (9) Revised Note 5 (4) Deleted former subsections 9.2, 9.3, and 9.4 and renum- (10) Revised Table 1 bered subsequent (11) Added Table 2 (5) Added Practice D7962, Guide D8164, Test Method E77, (12) Added Figs 1-5 Test Method E126, Terminology E344, Specification E2251, (13) Added Annex A1, Annex A2, and Annex A3 and Guide E2877 to Section 2 ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website (www.astm.org) Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/ 12