ISO 4266-3:2024

International
Standard
ISO 4266-3
Second edition
Petroleum and liquid petroleum
2024-10
products — Measurement of level
and temperature in storage tanks by
automatic methods —
Part 3:
Measurement of level in pressurized
storage tanks (non-refrigerated)
Pétrole et produits pétroliers liquides — Mesurage du niveau et
de la température dans les réservoirs de stockage par méthodes
automatiques —
Partie 3: Mesurage du niveau dans les réservoirs de stockage sous
pression (non réfrigérés)
Reference number
© ISO 2024
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Published in Switzerland
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Contents Page
Foreword .v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Precautions . 2
4.1 Safety precautions .2
4.2 Equipment precautions .2
4.3 General precautions .3
5 Accuracy . 3
5.1 Intrinsic error of ALGs .3
5.2 Calibration prior to installation .4
5.3 Error caused by installation and operating conditions .4
5.4 Overall accuracy .4
5.4.1 General .4
5.4.2 Use of ALGs for fiscal/custody transfer applications .4
6 Installation of ALGs . 5
6.1 General .5
6.2 Mounting location .5
6.3 Manufacturer’s requirements .5
6.4 Installation .6
6.4.1 Installation of intrusive ullage ALGs mounted on still-wells .6
6.4.2 Installation of intrusive ullage ALGs using guide wires .7
6.4.3 Installation of non-intrusive ullage ALGs (e.g. microwave or radar) mounted on
still-wells .8
6.4.4 Location of ALG .10
6.4.5 Installation of ALGs other than those described in this document .10
6.5 Still-well design .10
7 Initial setting and initial verification of ALGs in the field .10
7.1 Preparation .10
7.1.1 Checking for critical distances .10
7.1.2 Checking for free movement of level-sensing element of intrusive ALGs.11
7.1.3 Checking for influences of changes in physical and electrical properties of the
product (vapour/liquid) . . . .11
7.2 Initial setting .11
7.2.1 General .11
7.2.2 Setting of intrusive ullage ALGs .11
7.2.3 Setting of non-intrusive ALGs. 12
7.2.4 Other ALGs not described in this document . 12
7.3 Initial field verification . 12
7.3.1 General . 12
7.3.2 V erification procedure . 13
7.3.3 Tolerance of initial field verification. 13
7.4 Record keeping . 13
8 Subsequent verification of ALGs .13
8.1 General . 13
8.2 Frequency of subsequent verification. 13
8.3 Procedure .14
8.4 Tolerance for subsequent verification of ALGs in fiscal/custody transfer application .14
8.5 Comparison of the ALG readings from current and previous verifications .14
8.6 Adjustment in subsequent verification . 15
9 Data communication and receiving .15

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Bibliography .16

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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels
and lubricants from natural or synthetic sources, Subcommittee SC 2, Measurement of petroleum and related
products.
This second edition cancels and replaces the first edition (ISO 4266-3:2002), which has been technically
revised.
The main changes are as follows:
— terms and definitions in Clause 3 have been updated;
— in 4.3.2, the level that is measured and recorded simultaneously with the temperatures has been clarified;
— in 5.2, the information on calibration prior to installation has been updated;
— in Clause 6, the design requirements for still-wells have been clarified and the limitation of non-perforated
still-wells removed.
A list of all parts in the ISO 4266 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

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International Standard ISO 4266-3:2024(en)
Petroleum and liquid petroleum products — Measurement
of level and temperature in storage tanks by automatic
methods —
Part 3:
Measurement of level in pressurized
...