ch 7.2 draft - api ballotsballots.api.org/copm/comq/ballots/docs/ch7p2_8-17ballotdraft.pdf · page...

Chapter 7.2 Draft This document is not an API Standard; it is under consideration within an API technical committee but has not received all approvals required to become an API Standard. It shall not be reproduced or circulated or quoted, in whole or in part, outside of API committee activities except with the approval of the Chairman of the committee having jurisdiction and staff of the API Standards Dept. Copyright API. All rights reserved.

Chapter 7.2 draft Issue 15 1 (3

Ch 7.2 draft Revision history Issue Date Issued by Modification

01Mar070a 01Mar07 Lennart Hägg Created

05Sep070b 05Sep072007-03-17

Roy Meyer Christian Skaug

- Inserted format agreed on conference call March 1st , 2007 (see MoM by Anne Brackett)

- Added page 1 and 2 and footer for reference during development of the document

- Revised section 9 and 10

15Feb08 Hiren Shah

19SEP09 19Sep092009 Anne Brackett Merged and updated with comments

Draft 1 Oct 31st 2010 Christian Skaug Accepted formatting changes. Redid table 3. Changed all “7.3” to “7.2”.

Draft 1 Nov 2nd 2010 Anne Brackett Accepted changes and readied for conference call.

Draft 2 Nov 9 2010 Anne Brackett Conference call. Changes discussed and made.

Draft 2a Feb 1, 2011 Roy Meyer Danny Walton

Ongoing revision based on Draft 2 for consideration at WG meeting of Feb 2, 2011

Draft 3 Feb 2nd and 28th

Anne Brackett Conference calls and revision of Draft 3 Incorporated information from Hap Thompson and Tom Patrick and cleared format and deletions that were accepted.

Draft 4 July 19, 2011 RCKM, DEW, Started to revise Maintenance sections and revise formats

Draft 5 Sept. 1, 2011 RCKM, DEW, RWL

Minor changes to Tables

Draft 6 Unknown

Draft 7 Unknown

Draft 8 March 2, 2013 RCKM Revision to static temperature measurement section, primarily to address tank stratification

Draft 9 Jan 13th 2016 Christian Skaug New document baseline created

Draft 10 Jan 21st 2016 RCKM Light reformatting.

Draft 11 Feb 28th 2016 Christian Skaug Accepted formatting etc from Draft 10 Aligning with Ch. 7.1



Draft 12 Sept 23rd 2016 Christian Skaug Updated based on comments from draft 11 Notes:

- Still awaiting API Ch 7.1 final released version

- Comment status have not been confirmed by the person giving the comment

- Some comments from draft 11 still remain Draft 13 2016-12-12 Christian Skaug - Updated based on comment log and input

from Fall meeting. Draft 14 2017-01-05 Christian Skaug - Updated after meeting Dec 16th 2016

Draft 15 2017-02-03 Christian Skaug - Updated after meeting Feb 1st 2017

Draft 16 2017-02-21 Christian Skaug - Updated after meeting Feb 21st 2017

Draft 17 2017-03-10 Christian Skaug - Annex A added - Definitions updated - Yellow-highlighted text remains to be

reviewed, expected to be done at Spring meeting Dallas 2017

Draft 18 2017-06-02 Christian Skaug - Updated after Spring meeting in Dallas

Draft 19 2017-07-14 Christian Skaug - Updated after meeting June 8th 2017 and input from Luke w.r.t. item 62&63 in comment log (yellow-highlighted)

Draft 20 2017-08-01 Christian Skaug - Updated with input w.r.t. dry block procedure (action item from MoM)

Draft 21 2017-08-14 Christian Skaug - Updated after meeting Aug 9th and addressing action items from meeting.

About this document Page 1 is not included in the draft of Ch. 7.2; it is only for reference during the development of this document. The drafts start at page 2 in this document. Manual of Petroleum Measurement Standards Chapter 7.2 Chapter 7.2 —Temperature Determination, Portable Electronic Thermometers



REVISION OF API CHAPTER 7 PORTABLE ELECTRONIC THERMOMETERS 1 Introduction ............................................................................................................. 6 2 Scope ....................................................................................................................... 7 3 Normative References ............................................................................................. 8 4 Terms, Definitions and Acronyms ........................................................................ 10

4.1 degree .................................................................................................................. 10 4.1.1 degree Celsius (°C) .........................................................................................10 4.1.2 Degree Fahrenheit (°F) ...................................................................................10

4.2 Temperature discrimination ................................................................................ 10 4.3 Thermometer ....................................................................................................... 10 4.4 Temperature sensor ............................................................................................. 10 4.5 Portable Electronic Thermometer (PET) ............................................................. 11 4.6 Digital Contact Thermometer (DCT) (referred to as Digital Thermometers) ..... 11 4.7 Reference Standard Thermometer ....................................................................... 11

5 General Precautions .............................................................................................. 12 5.1 Safety ................................................................................................................... 12 5.2 Mercury Warning ................................................................................................ 12 5.3 Equipment Precautions ........................................................................................ 12

6 Units of Measure ................................................................................................... 13 7 Equipment and Design Requirements ................................................................... 14

7.1 Environment ........................................................................................................ 14 7.2 Accuracy, Resolution and Discrimination ........................................................... 14 7.3 Stabilization ......................................................................................................... 15 7.4 Cable and Probe ................................................................................................... 15 7.5 Voltage Indicator ................................................................................................. 15 7.6 Additional Functionality ...................................................................................... 15 7.7 Thermowells ........................................................................................................ 15 7.7.1 Test Thermowells ............................................................................................16 7.7.2 Sensor Thermowells ........................................................................................16 7.7.3 Installation .......................................................................................................16

8 Procedures for Temperature Determination .......................................................... 18 8.1 General ................................................................................................................ 18 8.1.1 Equipment Damage .........................................................................................18 8.1.2 Equipment Cleaning ........................................................................................18 8.1.3 Special Circumstances ....................................................................................18

8.2 Static Temperature Determination ...................................................................... 18 8.2.1 Tank Temperature Stratification .....................................................................18 8.2.2 Ambient Temperature Measurement ..............................................................23 8.2.3 Timing of Temperature Measurement ............................................................24



8.2.4 Immersion Times ............................................................................................24 8.2.5 Taking Temperature Readings ........................................................................24 8.2.6 Reporting Temperatures ..................................................................................26

8.3 Dynamic Temperature Determination ................................................................. 26 9 Accuracy Requirements ........................................................................................ 27

9.1 PET Specification ................................................................................................ 27 9.2 PET Verification .................................................................................................. 27 9.3 Requirements for a reference standard thermometer........................................... 28 9.3.1 NMI Calibration and Certification ..................................................................28 9.3.2 In-house Calibration ........................................................................................28

9.4 Requirements for a dry block .............................................................................. 29 10 Inspection, verification anD calibration Requirements ...... Error! Bookmark not defined.

10.1 Inspection ............................................................................................................ 30 10.2 Verification .......................................................................................................... 30 10.2.1 General ............................................................................................................30 10.2.2 Initial Calibration in Factory ...........................................................................31 10.2.3 Daily (prior to use) verification in the field ....................................................31 10.2.4 Monthly verification .......................................................................................32

10.3 Calibration ........................................................................................................... 33 10.4 Record Keeping ................................................................................................... 34 A.1 Project Objective ..................................................................................................... 35 A.3 EQUIPMENT REQUIREMENT ............................................................................ 36 A.4 Results of Testing: .................................................................................................. 38 A.5 Further Information ................................................................................................. 38



FOREWORD

This foreword is for information and is not part of this standard. This standard discusses equipment, methods and procedures for determining the temperature of hydrocarbon liquids using fixed automatic tank temperature systems.

This standard contains, and supersedes, information that was formerly contained in the API Manual of Petroleum Measurement Standards (MPMS) Chapter 7 Temperature Determination.

For the purposes of business transactions, limits on error or measurement tolerance are usually set by law, regulation, or mutual agreement between contracting parties. This publication provides guidance on tolerances that are recommended for custody transfer applications, and also describes methods by which acceptable approaches to any desired accuracy can be achieved.

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to the standardization manager, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.



1 INTRODUCTION

The purpose of this standard is to describe methods and practices that may be used to obtain accurate temperature measurements of petroleum and petroleum products in storage tanks, ships and barges under static conditions by the use of a portable electronic thermometer (PET). The use of PETs for dynamic measurement applications is primarily covered in API MPMS Ch. 7.4, however, guidance is provided in this standard on the device itself including practices to ensure accuracy.

Previous versions of the Temperature Determination standard described various temperature methods and apparatus. They did not give much guidance to the user on specific applications or methods of verification and certification, and were oriented towards crude oil. This version will include guidance on calibration, verification, and certification of equipment used in liquid petroleum products, refinery feedstocks, and renewable fuel products. Annex (b) is reference material for the user which synthesizes the methods described in this section.

Temperature has a significant impact on the volumetric determination of liquid quantities when correcting observed volume to volume at standard conditions. As a result, the most accurate means for temperature determination should be used. For custody transfer, the means of temperature determination should be agreed to among the parties involved.



2 SCOPE

This chapter describes the methods, equipment, and procedures for manually determining the temperature of liquid petroleum and petroleum products by use of a portable electronic thermometer (PET).

This chapter discusses temperature measurement requirements in general for custody transfer, inventory control, and marine measurements. The actual method and equipment selected for temperature determination are left to the agreement of the parties involved.

The manual method covers:

Non-pressurized tanks and non-pressurized marine vessels Gas-blanketed tanks and gas-blanketed marine vessels

It does not cover hydrocarbons under pressures in excess of 21 kPa (3 psi gauge) or cryogenic temperature measurement, unless the tank is equipped with a thermowell.

The requirements of this chapter are based on practices for crude oils and petroleum products covered by API MPMS Ch. 11.1 (ASTM D1250). Requirements in this chapter may be used for other fluids and other applications. However, other applications may require different performance and installation specifications.



3 NORMATIVE REFERENCES

American Petroleum Institute (API)

API Manual of Petroleum Measurement Standards

Chapter 1 Terms and Definitions Chapter 3 Tank Gauging (all sections)

API RP 500 Recommended Practice for Classification of Locations for Electrical

Installations at Petroleum Facilities Classified as Class I Division 1 and Division 2

API RP 2003 Protection Against Ignitions Arising Out of Static, Lightening, and Stray

Currents

API RP 3000 Classifying and Loading of Crude Oil into Rail Tank Cars

ASTM

E2877, Standard Guide for Digital Contact Thermometers E77, Standard Test Method for Inspection and Verification of Thermometers E344, Terminology Relating to Thermometry and Hydrometry

OCIMF

International Safety Guide for Oil Tankers and Terminals (ISGOTT)

IMO

Safety of Life at Sea (SOLAS)

National Fire Protection Association (NFPA)

NFPA 70, National Electrical Code



National Institute of Standards and Testing (NIST) SP 1088, Maintenance and Validation of Liquid in Glass Thermometers


Chapter 7.2 draft Issue 15 10 (

4 TERMS, DEFINITIONS AND ACRONYMS

For the purpose of this document, the following definitions apply.

Refer to API Manual of Petroleum Measurement Standards (MPMS) Chapter 1 and ASTM E344 for the definition of terms used in this standard.

4.1 degree

4.1.1 degree Celsius (°C)

A derived unit of temperature in the International System of Units (SI).

4.1.2 Degree Fahrenheit (°F)

A non-SI unit of temperature used in the US Customary (USC) system of units. At any temperature, an interval of one degree Fahrenheit is the same as an interval of 5/9 degree Celsius. °F = (°C * 9/5) + 32

4.2 Temperature discrimination

The ability to sense and record the actual temperature of a liquid to the specified temperature increments.

4.3 Thermometer

A device that measures temperature using any of a variety of different principles. A thermometer has two important components: a temperature sensor in which some physical change occurs that is dependent on temperature, and some means of indicating or transmitting this physical change as a value.

4.4 Temperature sensor

A temperature sensor is one part of a thermometer in which some physical change occurs with temperature and converts this change into a value on a scale, (e.g. the scale on a liquid-in-glass thermometer, a digital device that displays a unit of measure).



4.5 Portable Electronic Thermometer (PET)

A PET is a sub-set of class “D” or better Digital Thermometer (per ASTM E 2877) with features specifically required to perform static measurements in the petroleum and petrochemical industry. These include but are not limited to the following features:

1. Probe and cable with a length for the application and readout device 2. made of materials resistant to product characteristics and temperature being

measured.

3. Intrinsic Safety Classification

4.6 Digital Contact Thermometer (DCT) (referred to as Digital Thermometers)

An electronic device (per ASTM E 2877) consisting of a digital display and associated temperature sensing probe.

4.7 Reference Standard Thermometer

National Metrology Institute (NMI) traceable thermometer of suitable resolution and accuracy.



5 GENERAL PRECAUTIONS

5.1 Safety

Safety shall be considered for the specification, installation and operation of all equipment. Refer to API RP 500 and NFPA 70 for guidance. When loading liquids that can accumulate static charges, refer to the precautions described in the International Safety Guide for Oil Tankers and Terminals, Safety of Life at Sea (ISGOTT), API MPMS Ch. 3, and API RP 2003.

Safety and material compatibility precautions should be taken into consideration when using PETs. The manufacturer recommendations on the use of the equipment should be followed. Users of PETs should comply with all applicable codes, regulations, API standards and the applicable national electrical safety standards (e.g. NFPA 70 in the U.S.).

All PETs used in marine service should be specified in accordance with the appropriate National or International (IMO, USCG, IEC, ISGOTT, ISO, etc.) marine electrical safety standards.

PETs shall be certified for use in the hazardous area classification appropriate to their use.

5.2 Mercury Warning

WARNING: Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) or Material Safety Data Sheet (MSDS) for details and the EPA website http://www.epa.gov/mercury/faq.htm for additional information. Users should be aware that selling mercury and/or mercury containing products into your state may be prohibited by state law.

5.3 Equipment Precautions

The following general precautions affect the accuracy and performance of all types of PETs. These precautions should be observed where they are applicable.

All PETs should be capable of withstanding the temperature and other environmental conditions likely to be encountered in the designated service. When a PET is used in a



corrosive service, any parts exposed to the liquid or vapor should be of durable, corrosion-resistant construction to avoid both product contamination and PET corrosion. PETs used in marine or onshore tank applications with an inert gas system (IGS) or blanket gas system should be designed to withstand the operating pressure of the gas. Consult the PET manufacturer recommendation.

The operational range limits, as well as the ambient impact on the measurement accuracy of all equipment as part of a temperature measurement system shall be clearly stated and provided by the equipment manufacturer.

The design and use of PETs may be subject to the approval of the national measurement organization or classification societies, who may have issued a general type approval for the design of the PET for the particular service for which it is to be employed. Type or pattern approval is normally issued after a PET has been subjected to a specific series of tests and is subject to the PET being used in an approved manner.

6 UNITS OF MEASURE

For custody transfer, the means of temperature determination should be agreed to among the parties involved. Temperatures referenced in this document are those defined by the International Temperature scale of 1990 (ITS-90). Temperatures may be measured and expressed in degrees Celsius or in degrees Fahrenheit. This standard presents both International System of Units (SI) and US Customary (USC) units, and either may be implemented. The presentations of both units are for the convenience of the user, and are not necessarily exact conversions. The units of implementation are typically determined by contract, regulatory requirement, the manufacturer, or the user calibration program. Once a system of units is chosen for a given application, they should not be arbitrarily changed. (See API MPMS Ch. 15.)



7 EQUIPMENT AND DESIGN REQUIREMENTS

A wide range of portable electronic thermometers are available which are designed to take spot temperatures at any location within a tank which is accessible from the available gauging access point(s).

The PET may be used as a precise measuring device for measuring the temperature of petroleum or petroleum product. It may also be used as reference thermometer for verifying the calibration of other (permanently installed) temperature measuring devices.

7.1 Environment

A PET unit used for tank measurement with the display and any ancillary devices shall:

be certified by a nationally or internationally recognized testing agency as safe for use in flammable atmospheres and with liquids that can accumulate static charges;

have a method of bonding to the vessel or structure; have a protective case or enclosure with appropriate ingress protection and be

self-contained; be robust and shock proof, but should be sufficiently light to be carried by an

operator without undue fatigue; be resistant to immersion in petroleum products, and at a minimum, be suitable for use for ambient temperatures of 0 °C to 35 °C

(32 °F to 95 °F).

7.2 Accuracy, Resolution and Discrimination

The PET shall be calibrated and verified within tolerances traceable to NMI and meet the resolution requirement as given in Table 6 for the intended application.

To enable calibration of the PET to meet the specified accuracy shown in Table 6, it should be done per the manufacturer instructions and provide the means for adjustment. If adjustment is needed, it should be performed by properly trained personnel and shall not be easily accessible. The PET should include a provision for sealing or otherwise securing the device after adjustment.

The display shall be clear and bold, with no possibility of misinterpretation, over the ambient and normal expected operational temperature ranges.

Select a PET to meet the temperature discrimination requirements of API MPMS Ch. 12.1.



7.3 Stabilization

Temperature reading of a PET has come to equilibrium in liquid when the reading vary less than +/- 0.1 ºC (+/- 0.2 ºF). The PET may also have a visual or audible method to indicating that the temperature reading has stabilized. Table 5 shows typical stabilization times in liquid but this may vary due the mass of the probe sensor assembly. See 7.7.1 concerning temperature equilibrium with Test Thermowells.

7.4 Cable and Probe

The cable connecting the sensing element to the measuring instrument shall be long enough to cover the full depth of the tanks for which the PET is likely to be used. It may be marked at meter or foot intervals in order to assist in lowering to the required level. In applications where the PET will be used with a thermowell, the probe dimensions shall permit full insertion into the thermowell.

Note, cables wrapped on a spool device may be damaged prematurely if used with heavy products such as asphalt or heated viscous products. A PET constructed with a hand-wrapped cable may be more appropriate for heavy or heated products.

7.5 Voltage Indicator

Include with each unit a test system or switches to indicate low battery voltage.

If the equipment has a rechargeable battery, provide a suitable voltage battery charger and only charge in a intrinsically safe area.

7.6 Additional Functionality

Additionally functionality such as listed below is not required but may be useful in some applications:

averaging of temperature readings;

min/max storage of temperature readings;

backlighted or illuminated display characters, or

visual or audio indication of temperature stabilization.

7.7 Thermowells

The use of thermowells is required to isolate the liquid material from the temperature sensor. There are two general classification types of thermowells: test wells and sensor wells.



Both these classifications of thermowells should be filled with conductive fluid, grease or paste to ensure proper temperature readings.

7.7.1 Test Thermowells

Test wells are thermowells installed for occasional use (temperature checking), and capped when not in use. Test wells shall be installed adjacent to sensor wells. A suggested location is within three pipe diameters (maximum to be determined by company policy) between the test well and sensor well. Capping prevents foreign material from accumulating in the well bore. The test well should be the same type as the sensor well which is used for the working device, but as a minimum the test well shall have the same insertion length and a bore large enough to allow the use of a PET. A clogged thermowell may cause measurement errors and may damage thermometers. It is recommended that thermowells be checked periodically for an accumulation of foreign material and cleaned if needed.

7.7.2 Sensor Thermowells

Sensor wells are thermowells installed for use with a permanently installed temperature sensor, and shall be matched to the temperature sensing device (thermometer, transmitter, etc.).

7.7.3 Thermowell Installation

Select the thermowell to conform to code and user installation practices.

If horizontal separable wells or sockets are used, install the thermowells at heights as shown in Table 1.



Table 1—Positioning of horizontal thermowells in pressurized tanks

Tank Type

_________________

Minimum Number of Thermowells

_____________________

Measurement Level ________________

Horizontal Cylindrical

2

One at middle of the tank and one 300 mm (12 in) above the

bottom of the tank

Spherical Height < 9 m

Spherical Height > 9 m

Upright Cylindrical

3

4

4

0.6 m (2 ft), 3.6 m (12 ft) and 6.6 m (22 ft) above bottom of

the tank

One 0.6 m (2 ft) above the bottom of the tank, one 1.2 m (4

ft) below upper capacity mark and two at equal intervals

between the top and bottom wells

Note: Additional temperature measurements may be taken for higher precision, if agreed to by all parties.

For static measurements, see API Ch 7.3 and for dynamic measurements, see API Ch 7.1 and Ch 7.4.



8 PROCEDURES FOR TEMPERATURE DETERMINATION

8.1 General

8.1.1 Equipment Damage

See Section 10.2 for inspection requirements prior to use. Do not use instruments dropped or damaged until they are verified or calibrated. Do not use instruments with a known bias after calibration in excess of the verification tolerance applicable for the instrument operating temperature range until they are repaired.

8.1.2 Equipment Cleaning

Cleaning the PET and probe after use is necessary to avoid cross contamination when measuring multiple products or grades, to prevent coatings or material build-ups that could impact measurement sensitivity, and to prevent probe cable degradation.

If the PET has been used in asphalt, it is critical to clean the cable to ensure the cable integrity for future use. A solvent may be required. After cleaning dry the probe with a cloth to prevent the formation of an insulating film on the sensor.

CAUTION: Solvents may be combustible and present other health hazards. Obtain a Safety Data Sheet for any solvent used and take necessary precautions.

8.1.3 Special Circumstances

Because of personnel safety and practicality reasons, for high temperature liquids such as asphalt, it may not be possible to use PETs for in-tank temperature measurements. An alternative may be to permanently install temperature measuring devices or PETs via an externally mounted thermowell. Note the use of these measurement procedures in gauging reports, along with any additional notes such as the timing and method of the device accuracy verification.

8.2 Static Temperature Determination

8.2.1 Tank Temperature Stratification

Temperature differences between the external environment and the tank liquid along with variations in product temperature as the tank is filled are primary causes of stratification. Heat sources internal to the tank may also result in stratification. The degree of



temperature stratification is dependent on the duration of the liquid in the tank, the homogeneity of the liquid, the ease with which natural convection or forced circulation results in temperature equilibrium and the temperature differential relative to the environment. Heavy viscous liquids and tank contents formed from a mix of different grades of liquid are more likely to experience temperature stratification. Liquids that are much warmer or colder than the external environment are also more likely to stratify as the ground temperature below the tank is often more moderate than the surrounding environmental temperature. For marine cargo tanks, the temperature in adjacent cargo tanks may also impact stratification. Tank insulation limits the impact of environmental temperature differences but may not completely eliminate it.

Temperatures in large tanks, greater than 745 m3 (5,000 bbl), are often stratified unless the tank contents are thoroughly mixed. In the vertical direction, temperature differences of as much as 3 °C (5 °F) are possible, and differences of 5 °C (9 °F) or more may occur.

Tank temperature stratification may be reduced by tank fill, empty and transfer procedures, the use of pumps and by in-tank mixers.

In the horizontal direction, the temperature differences are typically less than 0.5 °C (1 °F) for low and medium viscosity petroleum liquids. Somewhat higher differences may be expected in high viscosity petroleum liquids and very large diameter tanks.

As shown in Note 2 of Table 4, a difference between any two measurements of more than 1°C (2 °F) will require additional temperatures to be obtained at different levels that are equally spaced apart. The readings shall then be averaged and rounded to the nearest 0.05 °C (0.1 °F). All tanks with a nominal volume of less than 745 m3 (5,000 bbl) are assumed to be NOT stratified for the purpose of temperature measurement procedures outlined in this standard unless otherwise agreed by all parties impacted by the measurement.

8.2.2 Static Tank Temperature – Tanks

8.2.2.1. Storage, lease, ship and barge tanks (non-pressurized):

For static temperature determination in storage, lease, ship and barge tanks, take the minimum number of temperature measurements shown in Table 2 to calculate an average temperature.



Table 2—Minimum Number of Temperature Measurements for Various Depths of Hydrocarbon Liquid in Storage, Lease, Ship and Barge Tanks

Depth of Liquid _________________

Minimum Number of Temperature

Measurements

Measurement Level ________________

> 6.0 meters (20 feet)

>3.0 and ≤6.0 meters (>10 and ≤20 feet)

3

2

Middle of the upper, middle, and lower thirds

Middle of upper and lower halves

< 3.0 meters (10 feet) 1 Middle of liquid Notes: 1. For tanks with capacities less than 1590 cubic meters (10,000 barrels), and no temperature stratification,

one temperature measurement at the middle of the liquid can be used. Also, one temperature measurement at the middle of the liquid will suffice in ship or barge tanks containing less than 1590 cubic meters (10,000 barrels).

2. The temperature of a liquid in a storage tank or marine vessel can vary throughout its depth: therefore, when temperature differentials greater than 1 °C (2 °F) are found, an average temperature shall be obtained. This may be accomplished by taking temperatures at different levels that are equally spaced apart, averaging the readings, rounding off the result to the nearest 0.05 °C (0.1 °F), and reporting the result as the average temperature for the entire volume. In some cases, such as when a tank has a non-uniform cross-sectional area, it may be necessary to calculate a volume weighted average temperature.

3. Additional temperature measurements may be taken for higher precision, if agreed to by all parties. 4. The temperature for small crude oil lease tanks should be determined in accordance with the guidelines in

API MPMS Chapter 18.1.

Heavy cargoes, heated cargoes, blended cargoes, and cargoes in unheated tanks in very cold weather may tend to have temperature stratification within each tank. When this situation is observed, take extra temperature measurements. On high heat cargoes such as asphalt, it may be impossible to obtain representative temperatures with the use of a portable electronic thermometers; it may be necessary to use permanently installed temperature measuring devices. Note the use of a permanently installed measuring device in the report, along with when and how the device’s accuracy was verified.

On marine vessels, take temperatures in all tanks or compartments, and measure these temperatures using the measurement information and immersion times provided in Tables 1 and 5. For both ships and barges, determine the average temperature for each tank as described in Section 8.2.5.

The primary considerations of accurately determining temperature are (a) the size and location of cargo tanks, (b) whether or not heat has been applied to the cargo, (c) the



atmospheric and seawater temperatures, and (d) the degree of temperature stratification within the cargo.

When temperature differentials greater than 3 °C (5 °F) are found, take additional temperatures. The number of additional temperatures will vary with the temperature differential. However, equally space and average the temperatures accordingly. If there is insufficient [less than 100 mm (4 in)] on-board quantity (OBQ) or remaining onboard (ROB) volume to permit temperature measurement or if this material is below its pour point, it may be assumed to be at the standard temperature of 15 ºC (60 ºF). Take the temperature of any substantial OBQ or ROB volume at the mid-level of the hydrocarbon.

8.2.2.2. Horizontal Cylindrical Tanks (non-pressurized):

For static temperature determination in horizontal cylindrical tanks, take the minimum number of temperature measurements shown in Table 3 to calculate an average temperature.

Table 3 – Temperature Measurements for Horizontal Cylindrical Tanks

Liquid Depth Sampling Level

(Percent of Diameter) (Percent of Diameter Above Bottom)

Upper Middle Lower

100 80 50 20

90 75 50 20

80 70 50 20

70 50 20

60 50 20

50 40 20

40 20

30 15

20 10

10 5



8.2.2.3 Tank Cars and Tank Trucks (non-pressurized):

If the temperature of a tank car is not determined dynamically during the loading, temperatures should be taken on every tank car at the middle of the liquid. However, by mutual agreement, when loading multiple tank cars or with non-heated oil from one source, temperatures may be determined on the contents of at least 10% (a minimum of three tank cars) of the number of cars, selected at random. This assumes that all of the tank cars are of the same nominal size and that all of them are either insulated or all uninsulated. When a car is to be heated to facilitate discharge in cold weather, take the temperature of the contents of each car at the same time the car is gauged. In all cases, thermometer immersion times shall be in accordance with those specified in Table 5.

Before tank cars are loaded, determine the temperature of the volume in the heel of the tank car. The heel temperature may be assumed to be at ambient temperature, unless the heel volume exceeds 7% of the tank car capacity. In that case, a temperature needs to be measured in the middle of the heel level. (See API RP 3000.)

If the temperature in a tank truck is not determined dynamically during the loading, then the temperature should be taken at the middle of the liquid.

Take temperatures on every tank car at the middle of the liquid. However, by mutual agreement, when loading multiple tank cars or with non-heated oil from one source, determine temperatures on the contents of at least 10 % (a minimum of three tank cars) of the number of cars, selected at random. This assumes that all of the tank cars are of the same nominal size and that all of them are either insulated or all uninsulated. When a tank car is to be heated to facilitate discharge in cold weather, take the temperature of the contents of each tank car at the same time the tank car is gauged. In all cases, follow the provisions of Table 5 for thermometer immersion times.

Before tank cars are loaded with crude oil, determine the temperature of the volume in the heel of the tank car. Assume the heel temperature to be at ambient temperature, unless the heel volume exceeds 7 % of the tank car capacity. In that case, a temperature needs to be measured in the middle of the heel level. (See API RP 3000.)

All of the above section also applies to determination of the temperature in tank trucks.

8.2.2.4. Pressurized tanks:

A spherical or spheroidal-type tank may be equipped with either a vertical thermowell, horizontal separable wells or pressure locks which can be used for temperature determinations.



If a vertical thermowell is used, take and average temperature measurements according to Table 1 (volume-weighted averaging may be used).

If horizontal separable wells or sockets are used, take and average temperature measurements in the wells below the product liquid level.

8.2.3 Ambient Temperature Measurement

Tanks undergo expansion and contraction due to variations in ambient and product temperatures. Such expansion or contraction in tank volume may be computed once the tank shell temperature is determined. Tanks that have been calibrated in accordance with API MPMS Ch. 2 have capacity tables based on a specific tank shell temperature. If the observed tank shell temperature differs from the capacity table tank temperature, correct the volumes extracted from the table accordingly. To do this the tank shell temperature shall be determined.

The tank shell temperature for non-insulated tanks is a function of the liquid temperature and the ambient temperature. Since non-insulated storage tanks cannot readily be sheltered from the elements, ambient air temperature has to be considered, in addition to the liquid temperature, when calculating a correction factor to determine the effect of temperature on the steel shell of a tank as required by API MPMS Ch. 12.1.1.

Tsh = [(7 x TL) + Ta] / 8

Where:

Tsh = tank shell temperature TL = liquid temperature Ta = ambient temperature

Ambient temperature (Ta) is a representative atmospheric temperature in the vicinity of the tank farm. Ambient air temperature surrounding a storage tank is always an arbitrary, and usually a widely varying parameter. Therefore, it is difficult to determine the best place to measure it. For this reason alone, the uncertainty of this measurement can be ± 2.5 °C (5 °F). However, the ambient temperature component is only 1/8 of the total tank shell temperature (Tsh). Therefore the accuracy required for the measurement of the ambient temperature (Ta) is not as high as that required for the liquid temperature (TL).

The recommended methods of taking this temperature are:

A temperature device carried by the gauger into the tank area immediately prior to gauging tanks. Take at least one temperature reading in a shaded area. If more than one temperature is taken, average the readings.

Shaded external thermometers permanently mounted in the tank farm area.



Local on-site weather stations.

Temperature readings are to be taken at least 1 m (3 ft) from any obstructions or the ground. Additionally, allow sufficient time for the temperature reading to stabilize.

Thermometers used for this purpose shall have an accuracy (maximum permissible error) of 1 °C (2 °F) or better, which should be verified every three months. For reporting purposes, round the ambient temperature to the nearest whole degree.

8.2.4 Timing of Temperature Measurement

Measure temperatures concurrent with the liquid level measurement.

8.2.5 Immersion Times

Stabilize thermometers at the liquid temperature before they are read. To reach stability quickly, accomplish all measurements by continuously raising and lowering the probe approximately 0.3 m (1 ft) above and below the desired temperature measurement depth. Failure to induce movement will substantially increase the typical immersion times as shown in Table 5.

Table 5—Typical Immersion Times for PETs

kg/m3

@ 15°C

API Gravity @ 60 0F

In-Motion

<780 >50 30 seconds 825 to 779 40 to 49 30 seconds 876 to 824 30 to 39 45 seconds 934 to 875 20 to 29 45 seconds

>934 <20 75 seconds

Note:

These immersion times were established based on the test procedure outlined in Annex B. Failure to use these recommended times may result in incorrect temperature readings.

8.2.6 Taking Temperature Readings

The following procedure is recommended for measuring temperatures with a portable electronic thermometer:

1. To avoid static electricity discharge in explosive or flammable environments, attach the bonding cable to bare metal, ensuring a good connection with the



PET. This is particularly important for static temperature measurement; bond the PET to the vessel before opening the gauging hatch.

2. Turn on instrument and note battery condition. If low battery is indicated, replace the battery before the PET is used.

3. Ensure that the PET displays the correct temperature scale (Celsius or Fahrenheit) as required by the parties involved.

4. Place the sensing probe at the desired measurement location (in a thermowell, or at the appropriate depth in the tank) see Table 1, 2 or 3.

5. Ensure that the thermometer reading has stabilized before it is recorded.

When taking tank temperatures, to quickly reach stability, continuously raise and lower the probe approximately 0.3 meter (1 ft.) above and below the desired temperature measurement depth as shown in Table 4. Failure to induce movement will substantially increase the required immersion times (Annex B).

Consider the thermometer to have reached stability if the readout varies by not more than +/-0.1 °C (0.2 °F) for 30 seconds.

6. Record the temperature readout as displayed by the PET without rounding.

7. Repeat steps 4, 5, and 6 if multiple temperatures are required.

8. Apply thermometer calibration corrections and calculate an average temperature if applicable, see Section 8.2.6.

9. Round off the temperature to the required resolution and record the result, see Section 8.2.6.

10. After use, clean all the parts of the thermometer assembly with a suitable solvent, see further Section 8.1.2.

This procedure is also used for a low-pressure tank equipped with a gauge hatch or perforated standpipe. It may not be used for pressurized or inerted tanks fitted with vapor control valves.

For a tank equipped with a thermowell, obtain a temperature by reading a thermometer placed in the well with its sensing element at the desired liquid level.



The following accommodations should be made to obtain the best possible measurement:

1) Insure the sensor tip touches the bottom of the well. 2) The sensor minimum immersion depth needs to be covered by the conductive

fluid, grease or paste within the thermowell. (Typically the immersion level of a sensor tube is about 8 cm or 3 inches above the sensor tip.)

3) There are no typical stabilization times due to ambient conditions. In extreme hot or cold conditions stem conduction may affect the reading although the sensor is at the proper immersion depth. If these conditions are present the exposed stem length should be minimized or insulated. The measurement temperature will be at equilibrium when the reading varies by +/-0.1 degrees or less.

8.2.7 Reporting Temperatures

Record temperature readings as displayed on the PET without rounding. If a PET has a known bias after calibration within the verification tolerance over the manufacturer stated operating temperature range, record the calibration correction to the PET reading, apply it to the observed reading and record the result.

8.2.8 Single Point Temperatures:

If a single temperature is required, round the corrected observed temperature to the nearest tenth of a degree (0.1).

8.2.9 Average Temperatures:

If an average temperature is required, calculate the simple or volume-weighted average temperature using the recorded readings (corrected as detailed above) and then round the calculated averaged temperature to the nearest tenth of a degree (0.1).

8.3 Dynamic Temperature Determination

For all dynamic temperature measurement applications, refer to API MPMS Chapter 7.4 for guidance. This includes, but is not limited to, quantity transactions, metering, meter proving, prover calibrations, and density measurement.



9 ACCURACY REQUIREMENTS

The accuracy of a PET is established by comparison to a reference standard thermometer. Unless otherwise stated, the accuracy refers to any value established by the PET whether displayed, stored, or transmitted.

9.1 PET Specification

The specification in this table represent minimum acceptable accuracy for portable electronic thermometers used for custody transfer. Thermometers with better accuracy are available and may be specified by mutual agreement. Table 6 – PET Specification Resolution Accuracy Range of Required Accuracy

0.1 °C

± 0.1 °C ± 0.3 °C

0 to 100 °C > 100 °C

0.1 °F

± 0.2 °F ± 0.5 °F

0 to 200 °F > 200 °F

9.2 PET Verification

Compare operating thermometers that are used in static or dynamic measurement on a regular basis (see Section 10) to a temperature standard. The recommended allowable tolerances between the operating thermometer and the NMI traceable thermometer are shown in Table 7. A deviation greater than these limits indicates that corrective action is required in the form of calibration or replacement of the inaccurate thermometer. These limits may be subject to other guidelines existing in agreements, contracts, regulations, or company policy.

Table 7 is provided as a reference for limits considered acceptable for static and dynamic temperature determinations in custody transfer measurement of petroleum and petroleum products.



Table 7 – Allowable tolerances for Operating PET versus reference standard thermometer

Service °C °F

Ambient Temperature Measurement ± 1 ± 2 Static Measurement ± 0.25 ± 0.5 Note

1. Tolerances are for the specific service, not the accuracy of the PET

9.3 Requirements for a Reference Standard Thermometer

9.3.1 General

For the daily verification, a reference standard thermometer can either be an ASTM E2251 liquid-in-glass thermometer (LIGT) non-hazard or ASTM E1 mercury-in-glass thermometer (MIGT) or a ASTM E2877 accuracy class D or better PET.

For daily, monthly and yearly verification as well as calibration, a reference standard thermometer used for these purposes shall be traceable to a NMI such as NIST by means of a valid calibration certificate or an equivalent thermometer with accuracy traceable to a NMI (in-house calibration).

9.3.2 NMI Calibration and Certification

Temperature devices must be traceable to a NMI by means of a calibration certificate or report such as ASTM E2623.

Temperature devices may require checks or calibrations based on the use of a temperature-controlled source as reference. Because the use of such a source is often impractical in a field environment, this type of calibration is better accomplished in a controlled laboratory environment or a shop / test facility in accordance with manufacturer’s recommendations and ASTM E644.

9.3.3 In-house Calibration

Given that many companies have laboratories that provide NMI/NIST/API/ASTM procedures and calibrate using the most sophisticated methods; therefore, these labs may calibrate in-house by means of a calibration certificate or report such as ASTM E2623.

Perform calibration of electronic temperature devices in accordance with the recommended procedure provided by the manufacturer.



9.4 Requirements for a dry block

One dry block, or the combination of a dry block with a separate thermometer that is traceable to NMI meeting the following minimum specification:

1. Maintain block temperature to within +/- 0.05 ºC (0.1 degree ºF) 2. Equipment traceable to national standards and carry certifications 3. Minimum of two wells with minimum of 100 mm (4 inch)

immersion depths in the block with proper diameter sleeves for the probes

4. Meet all relevant electrical safety and area classification 5. Local readout to at least 0.1 degree unit resolution



10. Inspection, Verification and Calibration

10.1 General

Below procedures are for static applications. For dynamic applications, refer to API MPMS Chapter 7.4.

10.2 Inspection

PETs need to be clean and functional to ensure they are fit for purpose. Additionally, in some applications, PET certification is required.

Before and after each use, wipe all parts of the probe assembly that are exposed to remove any coating on the probe that may have formed from use. Dried coating on the probe may result in the formation of an insulating film of material that has the potential to impact the functionality and accuracy of the PET.

Where the use of a certified PET is required, confirm that the instrument certification is in compliance with contractual, regulatory or other specified requirements.

Prior to use, inspect for:

1. Mechanical damage at the junction between the cable and the probe

2. Cuts, breaks, or abrasion in the cable insulation

3. Damage to the bonding cable

4. Damage to the case body

5. Low battery voltage

6. Legibility of displays

If any of the issues above are noted, remove the PET from service until repaired. With regards to low battery voltage, if the manufacturer doesn’t provide a power level indicator then use a multimeter or other device to test to ensure that the required voltage level is available.

10.3 Verification

10.3.1 General



Below table summarizes the need for verification and calibration of operating PETs used for custody transfer.

Table 8 –Minimum Verification and Calibration requirements for PETs

Initial Calibration in

the Factory

Daily Verification

(prior to use)

Monthly Verification

Annual Calibration

Three points1)

One point

Two points

Three points

Note 1) Manufacturer’s instructions may vary

Inventory and ambient temperature requirement to be determined by company procedures.

10.3.2 Initial Calibration in Factory

Before initial use, and at least once a year thereafter, each PET shall be re-standardized in a laboratory or other qualified calibration facility. The PET shall be compared at three or more temperature points, near the midpoint and ends of the range, with either a NMI certified reference thermometer or an equivalent thermometer with accuracy traceable to NMI. The PET shall be calibrated in accordance with the manufacturer’s instructions. These standardization checks will ensure that accuracy is maintained within the limits given in Table 6.

10.3.3 Daily (prior to use) verification in the field

Before each use, or once per day (whichever is less frequent) PETs should be spot checked by comparing the ambient reading against a reference standard thermometer in liquid or by use of a dry-well device. If the PET readings differ by more than the tolerance listed in Table 7, re-verify the PET to ensure its out-of-tolerance and if so, calibrate the PET (see 10.3).

The following shall be considered when comparing in liquid:

- The actual water temperature should be within the range of operation



- The liquid bath shall be of sufficient size to ensure the sensor of the reference standard thermometer and the PET are fully submerged and not touching the sides or bottom.

- The comparison could be done in the field as well as in a laboratory

The following shall be considered when using a dry block:

- Set the temperature to the ambient temperature where the check is being made.

- The dry block and can be dialed to the appropriate temperature but the comparison is between the reference standard thermometer and PET. Place the thermometer in the dry block and compare the instrument against the reference standard thermometer

- Ensure to follow the manufacturer instructions with respect to sleeve size, stabilization time etc.

- It’s not recommended to utilize Liquid-in-glass thermometers in a dry block

Note that although the dry block can be dialed to the appropriate temperature, the comparison is between the reference standard thermometer and the instrument.

A study was performed within the API MIG replacement phase II project on which the recommendations have been based, see further a summary of this described in Appendix A.

10.3.4 Monthly verification

On a monthly schedule, the portable electronic thermometer shall be checked at two or more temperatures near the ends of its range against a NMI traceable reference thermometer or an equivalent thermometer with accuracy traceable to NMI

Make this check by either:

1. Placing the two thermometers side-by-side in liquid leaving them undisturbed for at least 10 minutes before making the comparative readings, or

2. Placing the thermometer in a dry block that has been verified against a NMI traceable reference thermometer.



Alternatively, the ice point (ASTM E77 and NIST SP 1088) and ambient temperature or expected operational temperature, may be used for the accuracy check. If the thermometer readings differ more than the tolerance listed in Table 6, the thermometer should be re-standardized (see 10.3).

In addition, the following physical checks should be made:

1. The junction between the cable and the probe should be checked for mechanical damage.

2. The cable insulation should be checked for cuts, breaks or abrasion. 3. Grounding cable should be checked for damage. 4. Case body should be checked for cracks or damage.

If any of the damage above is noted, the PET shall be removed from service until repaired.

10.4 Calibration

Periodically calibrate or verify all PETs used for custody transfer against reference standard thermometer as stated in Table 6 to assure proper performance. A periodic PET calibration or verification is necessary to ensure proper performance. However, differences in the readings may indicate the need for additional calibration or replacement of the device.

The PET shall be compared at three or more temperature points, near the midpoint and ends of the range, with either a reference standard thermometer or an equivalent certified thermometer with accuracy traceable to an NMI. The PET shall be calibrated in accordance with the manufacturer's instructions. These standardization checks will ensure that accuracy is maintained within the limits given in Table 6.

Only trained personnel with proper calibration equipment should perform the equipment calibration. A means to indicate that the calibration adjustment has not been tampered with should be provided.

Calibration of a PET includes both the temperature sensing device and conversion electronics. Replacement of a failed temperature sensing device would require re-certification.

See Section 9.3 for requirements for reference standard thermometers.



10.5 Record Keeping

Maintain accurate records for each portable electronic temperature instrument. Maintain calibration certificate with serial number of PET in a file structure showing dates of service and location. Copies of the PET annual calibration certificate shall accompany the PET during measurements taken for custody transfer.

For daily and monthly verifications, accurate records shall be kept.



Annex A

(Informative)

Mercury-in-Glass Thermometer Alternative Testing Phase II – Calibration Devices

A.1 Project Objective

Mercury in Glass Thermometers (MIGTs) are used in the temperature determination of petroleum products in various applications. Due to the potential hazards in handling Mercury, MIGTs are being phased out of use. The National Institute of Standards and Technology has stopped calibrating MIGTs and several states in the USA have banned the sale of MIGTs. Due to of their history of use and reliability, MIGTs have been considered the preferred method for the temperature measurement of petroleum products in the oil and gas industry. They are specified in the API Standard, MPMS Chapter 7 – Temperature Determination. Specifications for the types of mercury thermometers used in petroleum temperature measurement are specified in ASTM E1.

API, in collaboration with the U.S. Environmental Protection Agency, conducted a comparison study of Mercury in Glass Thermometers to other liquid-in-glass and digital thermometers in order to provide a comparison of the accuracies of each type of device and thus be able to specify alternatives to Mercury in Glass Thermometers, with confidence, in the API MPMS Standards for Temperature Determination.

Phase II is the evaluation of alternatives to Mercury in Glass Thermometers for the calibration of temperature measuring devices that are used in field and field laboratory environments. A testing protocol for Phase II has been developed, according to the requirements in API MPMS Chapter 7 – Temperature Determination and is in Exhibit C of this RFP.

A.2 Testing Protocol

Objective a): To evaluate the suitability of two alternative temperature measurement devices to mercury in glass thermometers (MIG) for use as reference device for the daily “field checks” of Portable Electronic Thermometers (PET) as per clause 8.2.1 in API MPMS Chapter 7, 1st edition, 2001. The test program will provide the necessary



data for the appropriate revisions to this clause to replace existing NMI certified or traceable mercury-in-glass thermometers (MIG).

The two types of alternate measurement devices to be evaluated are:

o electronic digital thermometer (Alt-e), ASTM E2877, accuracy class D (Table 2)

o non-Mercury Liquid-in-glass temperature measurement device (Alt-L), ASTM E2251, S63 (Table 1)

Objective b): To evaluate the suitability of a commercially available portable dry well device (meeting the specification in Part II) for use as an alternate medium to the water- in-bucket bath for the comparison of PET versus Alt-e in Objective a).

Mercury in Glass Thermometer was the reference thermometer for this study. Testing conducted at two separate ISO 17025 accredited laboratory, each using a different set of instrumentation in accordance with the protocol in Part III and Exhibit D, using the four testing environments as described below:

10.5 Outdoor ambient non-circulating bucket bath 10.6 Indoor ambient non-circulating bucket bath 10.7 Outdoor Portable Dry Well (API supplied) 10.8 Indoor Portable Dry Well (API supplied

A.3 EQUIPMENT REQUIREMENT

Prior to issue by API instruments had been assigned a blind reference, along with a set of calibration verification instructions quoted from the manufacturers' instructions.

10.8.1.1 Two (2) ASTM 63F Mercury Liquid in Glass Thermometers, meeting the requirement of ASTM E1, labeled as MIG 1, MIG 2, readable to 0.1 degree F resolution.

10.8.1.2 Three (3) ASTM S63F, or equivalent, Non-Mercury Liquid in Glass Thermometers, from three different manufacturers (if available), meeting the



requirement of ASTM E2251, labeled as ALT-L1, ALT-L2, ALT-L3, readable to 0.1 degree F resolution.

10.8.1.3 Three (3) Digital Thermometers, meeting the requirement of ASTM E2877, from three different manufacturers (if available), labeled as ALT-e1, ALT-e2, ALT-e3, meeting ASTM E2877, accuracy class D, with readout resolution to at least 0.1 degree F. Additional resolution is preferred for improved statistical analysis.

10.8.1.4 Three (3) Portable Electronic Thermometers, meeting the requirement of API Chapter 7, 1st edition, 2001, Table 3 (0 - 200 deg F) from three different manufacturers (if available), labeled as PET 1, PET 2, PET 3, with readout to at least 0.1 deg F. Additional resolution is preferred for improved statistical analysis.

10.8.1.5 One Portable Dry Well, meeting the following minimum specification:

10.8.1.5.1 Temperature Range: 32 to 120 degree F

10.8.1.5.2 Maintain block temperature to within +/- 0.1 degree F 10.8.1.5.3 Equipment traceable to national standards and carry certifications 10.8.1.5.4 Maximum heating and cooling time to within 15 minutes 10.8.1.5.5 Two sleeveless 4 inch dry access wells on the block 10.8.1.5.6 Well-to-well uniformity to ± 0.3 degree F with sensors of similar size at

equal depths within wells 10.8.1.5.7 Meet all relevant electrical safety and area classification 10.8.1.5.8 Local readout to at least 0.1 degree F resolution

The following equipment provided by the contractor:

Outdoor Ambient Bucket Bath – A bucket filled with ambient (tap) water not to exceed 89°F, of a size able to accept at least two MIG's, one PET, one Alt-e, one Alt-L simultaneously in respect to depth and capable of reading total immersion LIG thermometers per specification in Part II. The bath shall not be circulating or insulated to represent least favorable field conditions. The bath shall be positioned during test to minimize any wind impact.



Indoor Laboratory Bucket Bath - the same requirement as the Outdoor Ambient bucket bath, but located indoors, in the testing laboratory. The testing area should be clear from A/C drafts and vibrating units to avoid any kind of external interference.

A.4 Results of Testing: Study supports the follow conclusions:

Current Ch. 7 tolerance (0.5°F) for daily field verification of PET by liquid-in-glass (LIG) reference thermometers (Hg and non-Hg) in water-in-bucket medium is validated @ 99% coverage.

DCT (digital reference thermometers) can be used as an alternate to LIG, in both water-in-bucket and dry well; tolerance could be set to 0.4°F (for both media) @ 99% coverage.

For dry well, precision improvement in comparison has little influence on overall expected tolerance due to accommodation of calibration differences.

for above tolerance limits, single out-of-tolerance result should be rechecked and out-of-tolerance verified before re-calibration of PET

A.5 Further Information

To review all of the data obtained during this testing, See TR XXXX API /EPA Mercury in Glass Thermometer Replacement Testing Studies (currently under development)



Bibliography API MPMS Chapter 7.1, Liquid –in-Glass Thermometers, 2nd edition API MPMS Chapter 7.3, Fixed Automatic Tank Temperature Systems, 2nd edition API MPMS Chapter 7.4, Dynamic Temperature Measurement, 2nd edition

ch 7.2 draft - api ballotsballots.api.org/copm/comq/ballots/docs/ch7p2_8-17ballotdraft.pdf · page...

Documents