RFQ EVENT 396 Attachment C - NIST-105-4-2016.pdf

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RFQ Event 396 Attachment C

Specifications and Tolerances for Reference Standards and Field Standard Weights and Measures

Specifications and Tolerances for Liquefied Petroleum Gas and Anhydrous Ammonia Liquid Volumetric Provers

Editors:

Georgia L. Harris

Val R. Miller

Georgia L. Harris, Acting Chief Office of Weights and Measures

Physical Measurement Laboratory

This publication is available free of charge from:

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December 2016

U.S. Department of Commerce Penny Pritzker, Secretary

National Institute of Standards and Technology Willie May, Under Secretary of Commerce for Standards and Technology and Director

NIST 105-4Handbook December 2016

Supersedes 2010 Edition https://doi.org/10.6028/NIST.HB.105-4-2016

Specifications and Tolerances for Reference Standards and Field Standard Weights and Measures

4. Specifications and Tolerances for Liquefied Petroleum Gas and Anhydrous Ammonia Liquid Volumetric Provers

105-4

NIST

Handbook December 2016

Supersedes 2010 Edition

NIST Handbook 105-4 Page ii December 2016

Preface

NIST Handbook 105-4 contains specifications and tolerances recommended as minimum requirements for standards used by State and local weights and measures officials in the regulatory verification of meters used in quantity determination of pressurized liquid commodities. Other users may find this handbook helpful in the design of volumetric standards for measuring pressurized liquid commodities, but the requirements should not be considered mandatory for special applications outside of the scope of regulatory weights and measures.

Document History and Changes

This 2016 edition contained minor editorial changes and one major change associated with Section 4.10, Bleed Lines, and the corresponding bleed line section of the evaluation form. Due to several requests and comments associated with zeroing the provers, the acceptability of bleed lines was restored after gathering additional supporting comments and resolving proposed changes with a working group. Final proposed language regarding bleed lines was provided by Henry Oppermann (Seraphin Test Measure Company), with additional supporting comments received and resolved with the working group.

The 2016 revision of Handbook 105-4 includes the following changes:

• No retroactive requirements were added to the document. (2016)

• Liquid bleed lines are reinstated provided safety guidelines are considered. (2016)

The 2010 edition was finalized through a working group consisting of those who provided comments on draft versions, compilation and draft responses of all comments by Michelle Foncannon (NIST), with the final review and editing effort led by L.F. Eason (NIST contract).

Special acknowledgment is given to Emil Hazarian, metrologist with the L.A. County and U.S.

Navy, Measurement Science Department (retired) for preparing updated drawings and schematic diagrams. Thanks are also given to numerous metrologists (of both state and industry laboratories) for their technical review of several interim drafts. The following changes were made in the 2010 edition.

The 2010 revision of Handbook 105-4 included the following changes since it was first published in 1997:

• The definitions were changed. Liquefied Petroleum Gas (LPG) and anhydrous ammonia provers are pressurized volumetric field standards. A number of references and defined terms have been expanded. (2010)

• Specific references were listed to regulatory and safety requirements for the design of individual components of LPG and anhydrous ammonia provers that are beyond the scope of this document. (2010)

• Series 300 stainless steel was listed as the preferred material due to its corrosion resistance and lower maintenance requirements. (2010)

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• References to “pressure relief” valves and “hydrostatic relief” valves were corrected.

(2010)

• Clear coated aluminum was allowed for the scale plate material but all markings must be permanent (allows silk screen). (2010)

• A non-accredited volumetric field standard manufacturer must make it clear that calibration is required before use for Weights and Measures applications. (2010)

• Scale plate graduations must be no smaller in height than 2 mm (approximately 0.1 in).

(2010)

• The total span of graduations on pressurized volumetric field standards was standardized to be at least 4 % of the nominal volume. (2010)

• The reflex sight gauge must be integral to the neck (upper and lower) of the prover. This change eliminates temperature gradients between the liquid in the sight gauge and the liquid in the body of the prover. (2010)

• Liquid bleed lines were no longer allowed due to the safety and environmental concerns about venting LPG and anhydrous ammonia to the atmosphere. (2010) (Changed in 2016 to allow bleed lines.)

• The level condition of pressurized volumetric field standards is determined by using levels to plumb the neck. The levels on pressurized volumetric field standards must be adjusted to agree with this level condition. (2010)

• The tolerances for pressurized volumetric field standards were changed to ± 0.2 % of the nominal capacity. All points on the neck scale must be within this tolerance for the entire volume (not the neck volume). An additional neck uniformity tolerance of two (2) scale divisions from the nominal/zero to any point on the scale also applies. (2010)

• Values in the two tables were updated. (2010)

• The drawings for the figures were updated. (2010)

• An optional evaluation form was added to encourage uniform evaluation of pressurized volumetric field standards. (2010)

The first several drafts of this Handbook were written by James Clifford, metrologist with the State of Oregon. The first published edition was in 1997 and drafts were updated with assistance of Karl Herken, metrologist with the State of Kansas.

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NOTE Regarding Units of Measure:

The SI base unit of volume is the cubic meter (m3). The Twelfth General (International) Conference on Weights and Measures redefined the litre [herein spelled liter] as a "special name for the cubic decimeter," but agreed to permit the continuance of the terms liter (L) and milliliter (mL), except in association with measurements of the highest precision. The commercial measurement system in the United States continues to use gallons and cubic inches for practical applications and manufacturers in this industry continue to use U.S. Customary dimensions.

Since commercial applications in the United States use units other than SI or other accepted metric units, this document references common units in current use.

*Trade names used in this Handbook do not imply recommendation or endorsement by the National Institute of Standards and Technology.

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Table of Contents Preface ........................................................................................................................... iii

NOTE Regarding Units of Measure: .............................................................................................. v

Introduction

1 Scope

1.1 “Field Standard” Classification

1.2 Retroactivity

1.3 Future Designs

1.4 Safety Considerations

2 Reference Documents

2.1 American National Standards Institute (ANSI)

2.2 American Petroleum Institute (API)

2.3 American Society for Mechanical Engineers (ASME)

2.4 American Society for Testing and Materials (ASTM)

2.5 International Organization of Legal Metrology (OIML)

2.6 International Society of Automation (ISA)

2.7 National Fire Protection Association (NFPA)

2.8 National Institute of Standards and Technology (NIST), Office of Weights and

Measures (OWM)

2.9 Underwriters Laboratories (UL)

2.10 US Department of Labor, Occupational Safety and Health Administration (OSHA)

3 Terminology

4 Specifications

4.1 Physical Size

4.1.1 Size Declaration

4.1.2 Size Limitations

4.2 Reference Temperature and Pressure

4.3 Identification Markings

4.3.1 Placement

4.3.2 Identification Plate Content

4.3.3 Limitations on use

4.3.4 Material and Cross Contamination Safety

4.4 Metal Construction Materials

4.4.1 ASME Pressure Vessel Requirements

4.4.2 Pressurized Provers for Testing LP Gas Meters

4.4.3 Pressurized Provers for Testing Anhydrous Ammonia Meters

4.4.4 Associated Pressurized Hardware

4.4.5 Associated Non-Pressurized Hardware

4.4.6 Other Materials

4.5 Body

4.5.1 Pressure Vessel Compliance

4.5.2 Shape

4.5.3 Support Structure

4.6 Upper and Lower Necks

4.6.1 Design

4.6.2 Drain Plug

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4.7 Sight Gauges

4.7.1 Upper Sight Gauge

4.7.2 Lower Sight Gauge

4.7.3 Sight Gauge Mounting Plate

4.8 Scale Plates

4.8.1 Material

4.8.2 Mounting

4.8.3 Adjustment

4.8.4 Sealing

4.8.5 Scale Markings

4.8.6 Graduation Lines

4.8.7 Scale Plate Units

4.8.8 Dual Scale Calibration

4.8.9 Span of Graduations

4.9 Fill and Discharge (Pump Off) Lines and Valves

4.10 Bleed Lines

4.10.1 Anhydrous Ammonia Provers

4.10.2 LPG Provers

4.11 Thermometer Wells and Thermometers

4.11.1 ASME Compliance

4.11.2 Position

4.11.3 Design

4.11.4 Installation in Thermometer Wells

4.11.5 Electronic Thermometers

4.11.6 Liquid-in-Glass

4.11.7 Bi-Metal Dial Face Thermometers

4.11.8 Provision for Calibration

4.11.9 Additional Thermometer Wells

4.12 Hardware

4.12.1 External Piping Requirements

4.12.2 Pressure Gauge

4.12.3 Pressure Relief Valve

4.12.4 Hydrostatic Relief Valves

4.12.5 Excess Flow Valves and Back Check Valves

4.12.6 Vapor Pressure Equalization

4.13 Leveling

4.13.1 Leveling Jacks

4.13.2 Establishment of Level Condition

4.14 Levels

4.14.1 Position

4.14.2 Level Sensitivity

4.14.3 Bulls Eye Bubble Levels

4.14.4 Adjustment

4.14.5 Auxiliary Levels

4.15 Workmanship, Finish, and Appearance

4.15.1 Air Entrapment

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4.15.2 Finished Quality

4.15.3 Required Assemblies

4.15.4 Thread Connector Lubricant

4.15.5 Valve Operation

4.15.6 Metal Joints

4.15.7 Exterior Coatings

4.16 Other Requirements

4.16.1 Return Pump

4.16.2 Hoses

4.16.3 Protective Caps

4.16.4 Electrical Requirements

4.16.5 Braking System

4.16.6 Labeling and Placarding

5 Tolerances (Maximum Permissible Errors)

5.1 Capacity Tolerance

5.2 Neck Tolerance

5.2.1 Neck Calibration Tolerance

5.2.2 Neck Uniformity Tolerance

6 Verification Requirements

6.1 Legal Requirements

6.2 Traceability

6.3 Calibration Certificates

6.4 Initial and Periodic Verification

7 Test Methods and References

7.1 NIST IR 7383 Selected Volume Procedures, SOP 21

8 Uncertainties

8.1 Legal Applications

8.2 Sources of Variation

8.2.1 Accuracy

8.2.2 Repeatability

Table 1. Metric specifications and tolerances for pressurized volumetric field standards

Appendix 1. Optional LPG and Anhydrous Ammonia Pressurized Volumetric Field

Table 2. U.S. Customary specifications and tolerances for pressurized volumetric field standards

Standards Evaluation Form

Figure 1. Schematic Drawing of a LPG and Anhydrous Ammonia Prover and Associated

Hardware/Plumbing

Figure 2. Schematic Drawing of Gauge Plates (Top and Bottom)

Figure 3. 100 gal Retention Plate (schematic)

Schematic for Use of Prover in Meter Verification Figure 4.

References

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SPECIFICATIONS AND TOLERANCES

FOR REFERENCE STANDARDS AND FIELD STANDARD

WEIGHTS AND MEASURES

4. Specifications and Tolerances for

Liquefied Petroleum Gas and Anhydrous Ammonia

Liquid Volumetric Provers

These specifications and tolerances are recommended as minimum requirements for standards used by State and local weights and measures officials and others in the regulatory verification of meters used in quantity determination of pressurized liquid commodities. Other users may find this handbook helpful in the design of volumetric standards for measuring pressurized liquid commodities, but the requirements should not be considered mandatory for special applications outside of the scope of regulatory weights and measures.

Key words: back check valve; excess flow valve; hydrostatic relief valve; pressure vessels; pressure relief valve; pressurized volumetric field standards;

provers; specifications; vapor return; volumetric specifications and tolerances; weights and measures.

Introduction Pressurized volumetric field standards (pressurized provers) are used primarily to test commercial pressurized liquid measuring devices for compliance with commercial requirements.

Use of these field standards at all appropriate levels of manufacture, distribution, and weights and measures inspection will help promote accuracy and uniformity in commerce. The breadth of topics in this handbook is intended to provide information for manufacturers, calibration staff, weights and measures officials, and other end users. References are provided when additional information may be useful to the reader.

1 Scope

1.1 “Field Standard” Classification These specifications and tolerances are limited to pressurized, graduated neck type volumetric field standard provers. The field standards covered by this publication are intended to be used by weights and measures officials. Manufacturers and distributors of liquefied gases, service maintenance personnel, research and testing laboratories, and others concerned with volume measurements of pressurized liquids may find these specifications and tolerances useful. Use of these standards at all appropriate levels of manufacture, distribution, and weights and measures inspection will help promote accuracy and uniformity in commerce.

The terms “pressurized volumetric field standard”, “pressurized prover”, and “prover” as used in this publication refer to all sizes in general. The pressurized provers referenced here are those whose volume is established between a graduated bottom zero and the nominal volume point on the graduated neck scale, when pressurized to 689.4757 kPa (100 pounds per square inch gauge, or “psig”). The unit psig will be used hereafter to reflect the pressures in common usage in the United States.

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In some cases larger or special purpose pressurized provers may be required which are outside of the scope of this publication. For example, a large truck or trailer mounted pressurized volumetric field standard may be transported in a horizontal position and raised to vertical for use. Larger volumetric field standards may be built based on design considerations within this document, but they are not specifically covered. Additional performance, structural integrity, stability, and safety issues applicable to these larger standards, though outside of the scope of this handbook, must be considered.

1.2 Retroactivity

These specifications are not intended to make obsolete those field standards fabricated to meet prior specifications. All new pressurized volumetric field standards (provers) placed in service after March 1, 2010, must meet these requirements prior to certification for regulatory Weights and Measures (legal metrology) use.

Pressurized volumetric field standards fabricated to meet prior specifications may be used as long as they 1) comply with applicable ASME and NFPA requirements, 2) maintain the current tolerances, 3) meet the calibration repeatability requirement of 0.02 % of nominal volume, and 4) their performance is adequate to meet NIST Handbook 44 fundamental considerations (i.e., the correction plus the measurement uncertainty does not exceed one-third of the tolerance for the device being tested).

1.3 Future Designs

These specifications are not intended to limit innovation made possible by advances in technology or changes in the commercial field devices they are used to test. All design revisions should be evaluated by NIST for accuracy, repeatability, and suitability for task. Approved design revisions may be included in future revisions of this document.

1.4 Safety Considerations

This documentary standard involves hazardous materials, operations, and equipment and does not purport to address the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific safety information is documented in the American Petroleum Institute (API) references.

Although these specifications include pressurized volumetric field standards for liquefied petroleum gas (LPG) and anhydrous ammonia, these products cannot be interchanged in the use of the standard. Cross contamination of either product would create additional safety hazards to the inspector and user of the products. The user should evaluate all components of the system to ensure compatibility with the intended product to be measured.

Commercial volume measuring devices tested with these field standards are typically used to measure quantities of LPG, anhydrous ammonia, and other pressurized liquids in sealed systems.

These liquids are known hazardous materials and hazardous wastes if spilled/released. The user is encouraged to obtain Material Safety Data Sheets (MSDS), also called Safety Data Sheets (SDS), from the manufacturer of any product encountered. Federal and local safety and disposal regulations concerning hazardous materials encountered should be reviewed by the user.

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Ethyl mercaptan (ethanethiol) is added to LPG to make it easier to detect in case of a leak. It has a very strong odor that is detectable in very small concentrations. Anhydrous ammonia also has a very pungent odor. It is very caustic and hazardous. Therefore, field standards should be purged of product and the interior be thoroughly flushed with water prior to being submitted for test.

These calibrations should be conducted in a well ventilated area.

This handbook does not address possible emissions from field standards during their use in the testing of hydrocarbons or ammonia. Please note that venting propane in some situations may be prohibited by law.

Reference Documents Specifications in this handbook are based in part upon information contained in publications from various standards and safety organizations. Due to the hazardous nature of the products being measured, there are safety regulations and references for all major components of liquefied petroleum gas and anhydrous ammonia pressurized volumetric field standards. The following is a list of reference documents pertaining to liquefied petroleum gas and anhydrous ammonia regulations and safety engineering. These documents detail requirements for each component of liquefied petroleum gas and anhydrous ammonia pressurized volumetric field standards. This handbook is intended to be in compliance with the requirements of these documents. However, if a conflict is found between this handbook and the current version of the references cited below, the requirements of the regulatory agency cited supersede the requirements of this document. Any conflicts found should be brought to the attention of the NIST, Office of Weights and Measures (OWM) to be included in future revisions of this document.

2.1 American National Standards Institute (ANSI)1

2.1.1 ANSI/ISA RP12.06.01, Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety.

2.2 American Petroleum Institute (API)2

2.2.1 Manual of Petroleum Measurement Standards, Chapter 11.2.4, Temperature Correction for the Volume of NGL and LPG Tables 23E, 24E, 53E, 54E, 59E, 60E.

2.2.2 Manual of Petroleum Measurement Standards, Chapter 14.8, Liquefied Petroleum Gas Measurement.

2.3 American Society for Mechanical Engineers (ASME)3

2.3.1 ASME International Boiler and Pressure Vessel Code, Section VIII, Pressure Vessels.

2.4 American Society for Testing and Materials (ASTM)4

2.4.1 ASTM D1250 - 08(2013)e1 Standard Guide for Use of the Petroleum Measurement Tables.

2.4.2 Table 24, Volume Reduction to 60 °F.

2.4.2.1 Table 24B, Generalized Products, Correction of Volume to 60 °F against Relative Density 60/60 °F.

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2.4.3 Table 34, Reduction of Volume to 60 °F against S.G. 60/60 °F for Light Petroleum

Gases.

2.5 International Organization of Legal Metrology (OIML)5

2.5.1 International Recommendation, OIML R 117-1, Edition 2007 (E), Dynamic measuring systems for liquids other than water, Part 1: Metrological and technical requirements.

2.6 International Society of Automation (ISA)6

2.6.1 See ANSI/ISA RP12.06.01 referenced under ANSI above.

2.7 National Fire Protection Association (NFPA)7

2.7.1 NFPA 54, National Fuel Gas Code.

2.7.2 NFPA 58, Liquefied Petroleum Gas Code.

2.7.3 NFPA 58HB, LP-Gas Code Handbook.

2.7.4 NFPA 70, National Electrical Code.

2.8 National Institute of Standards and Technology (NIST), Office of Weights and

Measures (OWM)8

2.8.1 Handbook 44, Specifications, Tolerances, and Other Technical Requirements for

Weighing and Measuring Devices, see current edition, published annually.

2.8.2 NISTIR 7383, Selected Procedures for Volumetric Calibrations, Standard Operating

Procedure, 21, Calibration of LPG Provers. See current edition.

2.8.3 NIST Handbook 105-6, Specifications and Tolerances for Reference Standards and Field

Standard Weights and Measures, 6. Specifications and Tolerances for Thermometers. See current edition.

2.9 Underwriters Laboratories (UL)9

2.9.1 UL Standard 21, LP-Gas Hose.

2.9.2 UL Standard 25, Meters for Flammable and Combustible Liquids and LP-Gas.

2.9.3 UL Standard 51, Power-Operated Pumps for Anhydrous Ammonia and LP-Gas.

2.9.4 UL Standard 125, Valves for Anhydrous Ammonia and LP-Gas (Other Than Safety

Relief).

2.9.5 UL Standard 132, Safety Relief Valves for Anhydrous Ammonia and LP-Gas.

2.9.6 UL Standard 331, Strainers for Flammable Fluids and Anhydrous Ammonia.

2.9.7 UL Standard 495, Power-Operated Dispensing Devices for LP-Gas.

2.9.8 UL Standard 565, Liquid-Level Gauges and Indicators for Anhydrous Ammonia and LP-

Gas.

2.9.9 UL Standard 567, Emergency Breakaway Fittings, Swivel Connectors and Pipe-

Connection Fittings for Petroleum Products and LP-Gas.

2.9.10 UL Standard 569, Pigtails and Flexible Hose Connectors for LP-Gas.

2.9.11 UL Standard 644, UL Standard for Safety for Container Assemblies for LP-Gas.

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2.9.12 UL Standard 1203, Explosion-Proof and Dust-Ignition Electrical Equipment for Use in Hazardous (Classified) Locations.

2.9.13 UL Standard 2061, Adapters and Cylinder Connection Devices for Portable LP-Gas Cylinder Assemblies.

2.9.14 UL Standard 60079, Electrical Apparatus for Explosive Gas Atmospheres.

2.10 US Department of Labor, Occupational Safety and Health Administration

(OSHA)10

2.10.1 29 CFR, Part 1910 Occupational Safety and Health Standards, Subpart H - Hazardous Materials.

2.10.1.1 Standard 1910.101 - Compressed gases (general requirements).

2.10.1.2 Standard 1910.110 - Storage and handling of liquefied petroleum gases.

2.10.1.3 Standard 1910.111 - Storage and handling of anhydrous ammonia.

Terminology Anhydrous Ammonia. A relatively pure, very caustic and hazardous, form of ammonia, synthesized from nitrogen and hydrogen, combined at high temperatures and pressures in the presence of a catalytic agent. Used primarily as a fertilizer, or a refrigerant. It will react rapidly with copper, brass, zinc and many alloys, especially those containing copper. It boils at atmospheric pressure at -33.3 °C (-27.9 °F). Anhydrous Ammonia will contaminate LPG.

Back check valve. A valve designed to automatically prevent liquid or vapor from flowing in the wrong direction.

Capacity, nominal. The nominal capacity of a volumetric field standard is the volume used to designate the prover (e.g., 100 gal LPG prover). The nominal volume is defined between the nominal mark on the graduated upper neck gauge and the lower zero mark on a lower neck gauge on an LPG / anhydrous ammonia prover.

Cubical coefficient of thermal expansion. Three dimensional expansion or contraction of a material due to temperature change, expressed °C-1 or °F-1 (/°C or /°F).

Excess-Flow Valve (also called excess-flow check valve). A device designed to close, reducing or stopping the flow when the liquid or vapor passing through it exceeds a prescribed flow rate as determined by pressure differential. This is a safety device primarily designed to cut off flow in case of a ruptured line or hose.

Hydrostatic Relief Valve. A pressure relief valve designed to protect liquid-filled piping from excessive pressure and possible rupture.

Liquefied Petroleum Gas (LPG). Means a mixture of normally gaseous hydrocarbons, predominantly propane, or butane, or both, that has been liquefied by compression, cooling, or both to facilitate storage, transportation, and handling.

Plumb. The condition of being perpendicular to a horizontal plane, vertical.

Pressure Gauge. A calibrated test device capable of sensing and indicating from 0 psig to 300 psig in 5 psig increments (as applied to this specification).

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Pressure Relief Valve. A pressure relief valve designed to protect piping that is not in contact with liquid (i.e., a vapor return line) from excessive pressure and possible rupture.

Pressurized Prover. A mounted volumetric field standard (truck, trailer, or stationary) built to ASME Pressure Vessel Code specifications designed to test liquefied propane gas, anhydrous ammonia, or other liquids in a closed system at the pressure needed to maintain a liquid state at ambient temperatures.

Reference temperature. The temperature at which the pressurized volumetric field standard is intended to deliver its nominal capacity.

Reflex Sight Gauge. A liquid level gauge, designed in such a way as to cause the liquid level to disrupt the refraction of light, causing the liquid within the gauge to appear black.

Sight Flow Indicator. A fitting with windows, to visually observe flow through a pipe; may or may not be equipped with a mechanical flow indicator.

Standard. Physical realization or representation of a unit of measure. In the context of this handbook standard may mean a laboratory standard or a field standard.

Tolerance. Maximum permissible error: extreme value of measurement error, with respect to a known reference quantity value, permitted by specifications or regulations for a given measurement, measuring instrument, or measuring system.

Specifications

4.1 Physical Size

4.1.1 Size Declaration

The nominal volumes of pressurized volumetric field standards (pressurized provers) are represented by the nominal volume lines located on their upper scale plates. Recommended metric sizes are shown in Table 1 and U.S. Customary (inch-pound) sizes are shown in Table 2 at the end of this document. Nominal volumes in each system are ideally selected in multiples of 1, 2, and 5 (liters or gallons) to facilitate calibration. However, a prover may be built to any size to meet specific needs and which may be practically calibrated. Non-standard size volumetric field standards that comply with all other requirements shall be considered to be in full compliance with this standard.

4.1.2 Size Limitations

The largest pressurized volumetric field standard described in this document is 2000 L (500 gal).

Truck or trailer mounted provers must meet legal weight and width regulations. This will typically limit the maximum size of pressurized volumetric field standards (pressurized provers) intended for portable operation. Pressure vessel design limitations along with practical and available calibration methods will typically limit the size of stationary provers. Exceptions to these size limitations may be made for special applications if proper engineering and safety considerations are followed, but these special application provers are outside the scope of this document.

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4.2 Reference Temperature and Pressure

The following reference conditions shall be applied to pressurized volumetric field standards (pressurized provers) when calibrated to deliver a volume equal to its nominal capacity: 60 °F (15.56 °C) and 100 psig. International standards typically reference petroleum products to 15 °C. Temperature and pressure measurements shall meet the accuracy requirements of the procedure chosen and be traceable to national standards. The uncertainty of the calibration must be adequate to meet NIST Handbook 44 fundamental considerations (correction plus uncertainty does not exceed one-third of the tolerance for the device being tested). During use of pressurized volumetric field standards all measurement indications must be corrected to the reference temperature and pressure for correct application of meter tolerances.

4.3 Identification Markings

4.3.1 Placement

Identification information shall be engraved, embossed, or otherwise permanently placed on a stainless steel plate. The stainless steel plate must meet the requirements and be attached in accordance with National Fire Protection Association (NFPA) 58, Liquefied Petroleum Gas Code. All lettering shall be permanent, durable, weather resistant, impervious to the liquids the volumetric field standard is intended to measure, and if not engraved or embossed, of a contrasting color to that of the background of the data plate. This information (however placed) should be either laminated or coated with a clear protective coating to preserve its legibility indefinitely.

4.3.2 Identification Plate Content

Each identification plate shall be attached in a conspicuous place on the standard and shall bear the following information:

4.3.2.1 Nominal capacity;

4.3.2.2 Reference temperature for calibration;

4.3.2.3 Name and address of manufacturer;

4.3.2.4 Model number;

4.3.2.5 Non-repetitive serial or identification number;

4.3.2.6 Material identification;

4.3.2.7 Cubical coefficient of thermal expansion of material;

4.3.2.8 Drain time after cessation of main flow or the total drain time

4.3.2.9 Proof of ASME certification;

4.3.2.10 Maximum allowable working pressure;

4.3.2.11 Date and pressure to which hydrostatically tested; and

4.3.2.12 Inside diameters of upper and lower necks.

4.3.3 Limitations on use

Any limitations on use shall be clearly and permanently marked on any volumetric field standard intended to measure accurately only:

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.105-4-2016 http:4.3.2.12 http:4.3.2.11 http:4.3.2.10

4.3.3.1 Products having particular properties (i.e., anhydrous ammonia will contaminate LP gas);

4.3.3.2 Under specific installation or operating conditions; or

4.3.3.3 When used in conjunction with specific accessory equipment.

4.3.4 Material and Cross Contamination Safety

Care shall be taken to ensure that the materials used for the volumetric field standards, or any subsequent contamination of such materials, do not create a safety hazard.

NOTE: A pressurized volumetric field standard prover must be properly labeled and placarded according to DOT operational rules, NFPA 58, and other regulatory requirements. Local laws and regulations vary between jurisdictions. It is incumbent upon the user of a pressurized volumetric field standard prover to be aware of and comply with local laws and regulations regarding the labeling and placarding of pressurized volumetric field standard used to test hazardous materials.

4.3.4.1 Product Labeling

The user shall appropriately label a pressurized volumetric field standard in a conspicuous place according to the product it will be used to test. Labeling shall include “Anhydrous Ammonia Only”, “LPG Only”, or other similar identification of the specific type of pressurized liquid the standard will be used to test.

4.3.4.2 Multiple Products

If the standard is to be used for multiple products, all products that may be tested must be labeled with additional labeling detailing the method of purging or cleaning required between different products.

4.4 Metal Construction Materials

4.4.1 ASME Pressure Vessel Requirements

A pressurized volumetric field standard shall meet the requirements of Section VIII, Pressure Vessels of the American Society for Mechanical Engineers (ASME), International Boiler and Pressure Vessel Code.

4.4.2 Pressurized Provers for Testing LP Gas Meters

A pressurized volumetric field standard used to test LP gas meters shall be constructed of either 300 series stainless steel (preferred) or low carbon steel. Construction must comply with all ASME pressure vessel requirements. 300 series stainless steel is more resistant to corrosion of the interior walls of the vessel and is the strongly preferred material. Corrosion of low carbon steel will cause the bottom sight gauge to become dirty and difficult to read. Since the sight gauges on pressurized volumetric field standards are not readily accessible for cleaning and a sight glass cannot be reused after removal, frequent replacement of sight gauges (and recalibration) is required. Corrosion will also eventually weaken the vessel.

4.4.3 Pressurized Provers for Testing Anhydrous Ammonia Meters Due to the corrosive nature of anhydrous ammonia, a pressurized volumetric field standard used to test anhydrous ammonia meters shall be constructed of 300 series stainless steel.

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4.4.4 Associated Pressurized Hardware

Piping, valves, fittings, handles and other associated hardware that are subjected to pressure may be constructed of other materials, provided they are compatible with the product tested and meet all applicable American Society for Mechanical Engineers (ASME) requirements. In addition, all pressurized hardware and fittings must meet National Fire Protection Association (NFPA), Underwriters Laboratories (UL), and US Department of Labor, Occupational Safety and Health Administration (OSHA) safety requirements, and any other regulatory requirements, including those requiring periodic maintenance, requalification, or replacement.

4.4.5 Associated Non-Pressurized Hardware

Brackets, fittings, handles and other associated hardware that are not subjected to pressure may be constructed of other materials, provided they are durable and are suitable for their intended purpose. These materials must also meet all applicable regulatory and safety requirements.

4.4.6 Other Materials

These specifications are not intended to preclude the use of other suitable materials, provided such materials conform to all ASME pressure vessel requirements, associated agency regulatory and safety requirements, and the applicable parts of these specifications. The material shall be of sufficient strength, shall be thermally stable, and not have an unduly high coefficient of thermal expansion which would render it unsuitable for field use. All applicable physical properties data must be accurately documented for the material chosen. Interested parties are urged to submit proposed designs to the National Institute of Standards and Technology (NIST), Office of Weights and Measures (OWM) for evaluation before fabrication is begun.

NOTE: These pressurized volumetric field standards are ASME containers. They do not meet the definition of a DOT container for DOT maintenance requirements. Therefore, periodic hydrostatic testing is typically not required. However, if local regulatory authorities do require a pressurized volumetric field standard to be hydrostatically tested, the standard should be recalibrated after testing since the hydrostatic test will expand the vessel slightly.

4.5 Body

4.5.1 Pressure Vessel Compliance

A pressurized volumetric field standard shall comply with all applicable requirements of Section VIII, Pressure Vessels of the American Society for Mechanical Engineers (ASME) International Boiler and Pressure Vessel Code. A LPG prover shall have a maximum allowable working pressure (MAWP) of 250 psig. An anhydrous ammonia prover shall have a maximum allowable working pressure (MAWP) of 300 psig.

4.5.2 Shape

Any cross section taken in a plane perpendicular to the vertical axis shall be circular, and the shape shall ensure complete emptying and draining. The volume of a prover shall be established without the use of fillers, adjusting plugs, or cavities of any kind.

4.5.3 Support Structure

The support structure of the pressurized volumetric field standard, consisting of legs and framework shall be attached to reinforcement plates on the body of the prover. The attachment

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4.6 Upper and Lower Necks

Upper and lower neck maximum diameter requirements are given in Tables 1 and 2 for different nominal volumes. Additional specifications are listed below.

4.6.1 Design

The upper and lower neck shall be seamless pipe, smooth inside, and specially inspected and selected for uniformity in the circular cross section. The upper and lower neck axes shall be perpendicular to a level horizontal plane.

4.6.2 Drain Plug

The lower neck shall be provided with a threaded plug to facilitate cleaning for calibration and completely drain the prover after calibration. The bottom should have a slight slope to facilitate drainage of prover through the drain plug.

4.7 Sight Gauges

A pressurized volumetric field standard shall be equipped with two liquid level gauges of the reflex type mounted as an integral part of the upper and lower neck. The liquid level gauges and retaining plates shall meet the requirements of UL Standard 565, Liquid-Level Gauges and Indicators for Anhydrous Ammonia and LP-Gas and all applicable ASME requirements.

4.7.1 Upper Sight Gauge

The sight gauge shall be capable of displaying a volume not less than 4 % of the prover nominal volume.

NOTE: Available sight gauges can display more than 4 % of the prover nominal volume. This design extends the application of the prover for the user.

4.7.2 Lower Sight Gauge

A pressurized volumetric field standard shall have a bottom zeroing capability (also called wet zero). The wet zero shall have a similar type liquid level gauge as the top neck adequate for establishing the zero set-point. To facilitate the ability to see and stop the liquid drain in time to set the zero, the lower sight gauge assembly shall display a minimum length of 10 cm (approximately 6 in) of liquid level in the lower neck.

4.7.3 Sight Gauge Mounting Plate

The width of the opening in the sight gauge mounting plates (upper and lower) shall be at least

12.7 mm (0.5 in) to allow for a clear view of the liquid level in the sight gauge.

NOTE: The sight gauge and mounting plate must meet the requirements of Section VIII, Pressure Vessels, of the ASME, International Boiler and Pressure Vessel Code. If an opening of

12.7 mm (0.5 in) or larger is not approved for a specific application, an approved sight gauge and mounting plate with the widest allowed opening shall be used. Regardless of the width of the opening, the scale plates shall not extend past the bevel of the retaining plate opening by more than 1 mm (approximately 0.04 in) to allow the best possible view of the liquid level.

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4.8 Scale Plates

4.8.1 Material

The scale plate shall be rigid and resistant to corrosion and discoloration (i.e., anodized aluminum, clear coated aluminum, or stainless steel).

4.8.2 Mounting

There shall be a sufficient number of scale brackets (minimum of two per scale plate) to hold the plate firmly. These brackets will be independent of the sight gauge retaining plate bolts. The scale plates shall be securely attached to the brackets and be provided with a means for sealing.

4.8.2.1 Location

The scale plates shall be mounted on the sight gauge mounting plate, parallel to the face of the reflex liquid level gauge.

4.8.2.2 Parallax

To minimize the effects of parallax, the graduated edge of the scale plates shall be bent in toward the sight gauge in conformation with the angle of the mounting plate bevel. When viewed from directly in front of the sight gauge, the graduated edge(s) of the scale plate(s) shall be within ± 1 mm (approximately ± 0.04 in) of the line of view along the perpendicular edge of the mounting plate for the sight gauge.

4.8.2.3 Maximum liquid level visibility

In order to allow the best possible view of the liquid level, the scale plates shall not extend past the bevel of the retaining plate opening.

4.8.3 Adjustment

4.8.3.1 Top scale plate(s)

Movement of the top scale plate(s) of a pressurized volumetric field standard prover shall be used to adjust the volume of the prover. Adjustment or removal of the upper scale plate(s) shall not require loosening, removal, or any other manipulation of the sight gauge retaining plate bolts.

4.8.3.2 Incremental adjustment

Where the design of the scale adjustment provides for movement of the scale by increments only, the maximum increment shall be no larger than 25 % of the smallest scale division.

4.8.3.3 Lower scale plate(s)

The lower scale plate(s) of a pressurized volumetric field standard prover shall be fixed in position with provision for sealing. Removal of the lower scale plate(s) shall not require loosening, removal, or any other manipulation of the sight gauge retaining plate bolts.

4.8.4 Sealing

All adjustments shall be provided with a means for sealing which will prevent movement or play.

Removal or movement of any adjusting mechanism or scale plates (top and bottom) shall not be possible without breaking the seal. Any gauge movement or play in the adjustment mechanism or scale plates after tightening or sealing the adjustment mechanism shall be less than 25 % of the smallest scale division.

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4.8.4.1 Manufacturer’s seals on new volumetric field standards

A manufacturer that is not accredited by an Accreditation Body that is a signatory to the International Laboratory Accreditation Cooperation (ILAC) mutual recognition agreement (for the appropriate scope of volume calibration), shall not seal a new volumetric field standard unless a tag attached to the seal (or a label obscuring the view of the sight gauge) clearly states that calibration is required before the measure can be used for Weights and Measures applications.

4.8.5 Scale Markings

The graduation lines, numbers, and other inscriptions on the scale plate shall be permanent, durable, weather resistant, impervious to the liquids the volumetric field standard is intended to measure, and of a contrasting color to that of the gauge plate. All letters and numbers on a scale plate shall be legible and of adequate size, in no event smaller in height than 2 mm (approximately 0.08 in).

4.8.5.1 Nominal volume and unit indication

Scale plates shall be clearly marked with the nominal volume of the standard and the identification of the unit of measurement used on the scale plate. Proper abbreviations may be used for the unit of measurement (i.e., “gal”, “in3”, “L”, “mL”, etc.).

4.8.5.2 Nominal volume line

The nominal volume or zero lines on all top neck scale plates shall extend across the entire width of the scale plate (except as allowed for dual unit scale plates) and shall be clearly identified with the nominal volume of the volumetric field standard.

4.8.5.3 Bottom zero line

The bottom zero scale plate on of a pressurized volumetric field standard prover shall have a line extending across the entire width of the scale plate. This line shall be clearly marked as the “zero” or “0” line.

4.8.5.4 Additional marking

The intended method of use, either “To Contain” or “To Deliver” shall also be clearly marked on the top scale plate. LPG and Anhydrous Ammonia provers are typically used “To Deliver.”

4.8.6 Graduation Lines

4.8.6.1 Graduation line length - Major divisions

Convenient major (numbered) graduation lines, consistent with the measurement system used, shall meet with the maximum value requirements listed in Tables 1 and 2. Major graduations shall be numbered to indicate the volume and shall be twice the length of any subdivision lines.

Major divisions shall be at least 6 mm (approximately 0.24 in) in length.

4.8.6.2 Graduation line length – Subdivisions

Any subdivision graduation lines shall be at least 3 mm (approximately 0.12 in) in length.

4.8.6.3 Graduation line width

Graduation lines shall be of uniform width and not more than 0.6 mm (approximately 0.024 in) or less than 0.4 mm (approximately 0.016 in) wide.

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4.8.6.4 Line position

All graduation lines shall extend to the edge of the scale plate nearest to the sight gauge.

4.8.6.5 Graduation line spacing

The minimum distance between the center of any adjacent graduations lines shall be 1.6 mm (approximately 1/16th in or 0.0625 in) and the lines shall be evenly spaced.

4.8.7 Scale Plate Units

The basic scale on metric standards shall be milliliters. The basic scale on U.S. Customary standards shall be decimal gallons (0.1 gal). Maximum graduation volumes are listed in Table 1 (metric) and Table 2 (U.S. Customary). Subdivision graduations (if present) shall be either one-half (1/2), one-fourth (1/4), one-fifth (1/5), or one-tenth (1/10) of the volume of the major divisions.

4.8.7.1 Additional bottom scale plate graduations

Additional graduations are allowed for the convenience of the user in the evaluation of wet down characteristics of the vessel. If present, these graduations will be clearly differentiated from the zero line and clearly identified. If present, it is recommended that the bottom scale plate major graduations be 50 mL (0.01 gal) and minor divisions (subdivisions) 25 mL (0.005 gal), consistent with the measurement system used.

4.8.7.2 Dual unit scale plates

A volumetric field standard graduated in multiple (dual) units, shall have each nominal capacity mark clearly identified. The units of measure will also be clearly identified for each scale.

4.8.7.3 Dual units - Two scale plates

If two scale plates are used with dual unit scales, each shall be capable of being adjusted and sealed independently. Both shall be adjusted as close to nominal as possible during calibration.

4.8.7.4 Dual units - Single scale plate

A single piece dual unit scale plate is acceptable as long as the units are clearly defined, the two scales are clearly separated, the conversion between units across the scale plate is accurate, and each scale unit is clearly identified.

4.8.7.5 Lack of confusion

Additional care must be taken in the design of any dual scale plate(s) to ensure there is no confusion between units.

4.8.8 Dual Scale Calibration

A calibration certificate for a volumetric field standard with dual units must include calibration values for both scale plates. If the secondary scale was adjusted based on conversion of the units of the primary scale, it must be clear which scale was adjusted based on the calibration and which was adjusted based on the mathematical conversion (e.g., a 25 gal calibration with nominal zero adjusted to 25.0 gal and a 95 L nominal mark adjusted to coincide with the + 0.096 gal indication on the U.S. Customary scale plate based on the calculated conversion that 95 L is approximately 25.096 gal).

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4.8.9 Span of Graduations

The graduated section of the scale plate shall cover at least 4 % of the nominal volume of the prover. The scales shall be graduated both above and below the nominal capacity graduation by an amount not less than 1.5 % of the nominal volume of the pressurized volumetric field standard prover.

NOTE: If a sight gauge is used that allows viewing of more than the minimum required, graduations should span the entire sight gauge. If 1.5 % of the volume is above the nominal value, 2.5 % must be below the nominal value to equal 4 percent.

4.9 Fill and Discharge (Pump Off) Lines and Valves

Two fast acting shut off valves specifically designed for LPG and/or anhydrous ammonia must be positioned at the bottom of the lower neck of the pressurized volumetric field standard, below the bottom zero level, to allow filling and draining of the prover. These valves must be protected with appropriate excess flow and/or back check valves. These valves must comply with UL Standard 125, Valves for Anhydrous Ammonia and LP-Gas (Other Than Safety Relief) and any other applicable safety standards.

4.10 Bleed Lines

A bleed line is a valve and piping attached to the bottom fill valve or to the piping between the bottom fill valve and the prover body to facilitate the adjustment of the zero level.

NOTE: Bleed lines present both safety and environmental hazards associated with venting LP gas or anhydrous ammonia to the atmosphere.