Detail of GB/T 21451.4-2008

Introduction of GB/T 21451.4-2008

1 Scope This part of GB/T 21451 gives guidance on the selection, accuracy, installation, commissioning, calibration and verification of automatic tank thermometers (ATTs) in transfer applications in which the ATT is used for measuring the temperature of petroleum and liquid petroleum products having a Reid vapour pressure less than 100 kPa, stored in atmospheric storage tanks. This part of GB/T 21451 is not applicable to the measurement of temperature in caverns or in refrigerated storage tanks. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part. For dated references, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest editions apply to this part. GB/T 8927 Petroleum and liquid petroleum products—Temperature measurement—Manual methods (GB/T 8927-2008, ISO 4268: 2000, MOD) ISO 4266-1 Petroleum and liquid petroleum products—Measurement of level and temperature in storage tanks by automatic methods—Part 1: Measurement of level in atmospheric tanks ISO 1998 (All parts) Petroleum industry—Terminology 3 Terms and definitions For the purposes of this part of GB/T 21451, the terms and definitions given in ISO 1998, and the following, apply. 3.1 automatic tank thermometer ATT instrument that continuously measures temperature in storage tanks Note: An ATT, which may also be known as an automatic tank temperature system, typically includes precision temperature sensors, field-mounted transmitters for electronic signal transmission, and receiving/readout device(s). 3.2 resistance temperature detector RTD electrical temperature-sensing element in common use to measure the temperature of the contents of a storage tank 3.3 single-point ATT spot ATT ATT that measures the temperature at a particular point in a tank by the spot temperature element 3.4 multiple-point ATT ATT consisting of multiple (usually three or more) spot temperature elements to measure the temperature(s) at selected liquid level(s) Note: The readout equipment should average the readings from the submerged temperature elements to compute the average temperature of the liquid in the tank, and may also display the temperature profile in the tank. 3.5 Averaging ATT 3.5.1 multiple-point averaging ATT averaging ATT where the readout equipment selects the individual, spot temperature element(s) that are submerged in the liquid to determine the average temperature of the liquid in the tank 3.5.2 variable-length- averaging ATT averaging ATT consisting of several temperature elements of varying length, with all the elements extending upwards from a position close to the bottom of the tank, and where the readout equipment selects the longest, completely submerged temperature element to determine the average temperature of the liquid in the tank 3.6 temperature transmitter instrument that typically provides electrical power to the temperature element(s), converts the temperature measured by the element(s) to an electrical or electronic signal, and transmits the signal to a remote readout Note: A local readout may be provided. Often, the function of the temperature transmitter is provided by the level transmitter of the automatic level gauge (ALG).

Contents of GB/T 21451.4-2008

Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Precautions 5 Accuracy 6 Selection of ATTs 7 Description of ATT equipment 8 Installation of ATTs 9 Calibration and field verification of ATTs 10 Data communication and receiving