hims_htg & vapor pressure (p3) measurement_4416645_rev1[1]

Instruction manual HIMS / HTG and vapour pressure (P3) measurement Page 1

Instruction manual HIMS / HTG and vapourpressure (P3) measurementDecember 2006Part no. 4416.645Rev. 1

Enraf B.V.P.O. Box 8122600 AV DelftNetherlands

Tel. : +31 15 2701100Fax : +31 15 2701111E-mail : [email protected] page : http://www.enraf.com

Copyright 2003- 2006 Enraf B.V. All rights reserved.

Reproduction in any form without the prior consent of Enraf B.V. is not allowed. This manual is for informationonly. The contents, descriptions and specifications are subject to change without notice. Enraf B.V. accepts noresponsibility for any errors that may appear in this manual.

The warranty terms and conditions applicable in the country of purchase in respect to Enraf B.V. products areavailable from your supplier. Please retain them with your proof of purchase.

Preface


PrefaceThis manual is intended for technicians involved with the commissioning and service of the Enraf gauges withthe optional HCU board or ICU_HPI board installed for the function of HIMS (Hybrid Inventory MeasurementSystem), HTG (Hydrostatic Tank Gauge) and vapour pressure measurement with pressure transmitter P3.

A description preceding the technical procedures gives the technical information necessary to understand itsfunctioning. It is recommended to read this description prior to performing any of the procedures.

Safety and prevention of damage

Refer to the chapter Safety in the instruction manual of the applicable instrument (servo/radar gauge or indicator)for detailed safety instructions.

"Warnings", "Cautions", and "Notes" have been used throughout this manual to bring special matters to theimmediate attention of the reader.

A Warning concerns danger to the safety of the technician or user; A Caution draws attention to an action which may damage the equipment; A Note points out a statement deserving more emphasis than the general text, but does not deserve a

"Warning" or a "Caution".

The sequence of steps in a procedure may also be important from the point of view of personal safety andprevention of damage; it is therefore advised not to change the sequence of procedural steps or alter aprocedure.

Legal aspects

The information in this manual is the copyright property of Enraf B.V., Netherlands.Enraf B.V. disclaims any responsibility for personal injury or damage to equipment caused by:

Deviation from any of the prescribed procedures; Execution of activities that are not prescribed; Neglect of the general safety precautions for handling tools, use of electricity and microwave radiation.

EC declaration of conformity

The Enraf instrument, in which the optional HCU or ICU_HPI board is installed, is in conformity with theprotection requirements of EC Counsel Directive 93/68/EEC. Refer to the CE declaration of conformity deliveredwith the instrument.

Additional information

Please do not hesitate to contact Enraf or its representative if you require additional information.

Table of contents

Page 4

Table of contentsPreface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.1 HCU board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.2 ICU_HPI board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.3 Overview of functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.4 HCU compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.4.1 Replacement or adding optional board in 854 ATG or 854 XTG servo gauges . . . . . . . . . . 81.4.2 Replacement or adding optional board in 873 SmartRadar . . . . . . . . . . . . . . . . . . . . . . . . . 81.4.3 Replacement or adding optional board in 877 FDI Field Display & Interface . . . . . . . . . . . . 8

1.5 Optional functions in this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2 HIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.1 Introduction into HIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1.1 HIMS calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.1.2 Corrections for ambient air and vapour density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.2 Commissioning of HIMS system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.2.1 Selecting pressure and density dimension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.2.2 Tank and gauge data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.3 Set-up and configuration of the pressure transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.2.4 Zero calibration of the pressure transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.2.5 Compensation for pressure transmitter P1 position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3.1 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3.2 Manual inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3.3 Data items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3 HTG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.1 Introduction into HTG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.1.1 HTG calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.1.2 Volume and Mass calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.1.3 Corrections for ambient air and vapour density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.2 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.2.1 Selecting pressure and density dimension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.2.2 Tank and gauge data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223.2.3 Alarm settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.2.4 Ullage readout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.2.5 Set-up and configuration of the pressure transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.2.6 Zero calibration of the pressure transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.2.7 Compensation for pressure transmitter P1 - P2 distance . . . . . . . . . . . . . . . . . . . . . . . . . . 26

3.3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.3.1 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.3.2 Manual inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.3.3 Data items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table of contents


4 Vapour pressure (P3) measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294.1 Introduction into vapour pressure measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294.2 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

4.2.1 Selecting pressure dimension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.2.2 Gauge data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.2.3 Set-up and configuration of the pressure transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.2.4 Zero calibration of the pressure transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.3.1 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.3.2 Manual input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.3.3 Data items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5 Maintenance and troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.1 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.2 Troubleshooting HIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.3 Troubleshooting HTG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345.4 Troubleshooting vapour pressure (P3) measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.5 Hydrostatic error request (item EH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.6 Hydrostatic status request (item QF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.7 HART device pointer (items VP and VV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Appendix A ASCII table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Appendix B1 Assessment of distance LP for HIMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Appendix B2 Assessment of distance LP (and LS) for HTG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Appendix C Local gravity constant (item LG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Appendix D Ambient air density (item RF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Appendix E Vapour density (items RG and RJ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Appendix F1 Define values for hydrostatic deformation (items IF and IL) for HIMS . . . . . . . . . . . . . . . . 46Appendix F2 Define values for hydrostatic deformation (items IF and IL) for HTG . . . . . . . . . . . . . . . . . 47Appendix G SET-up and Configuration procedure for HART pressure transmitters with the HART

Communicator model 275 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Appendix H Zero calibration of pressure transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Appendix J Related documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Introduction

Page 6

1 Introduction

1.1 HCU board

The optional HCU board is used in Enraf servo gauges 854 ATG, 854 XTG, Enraf 873 SmartRadar and EnrafField Indicator 877 FDI to interface optional equipment as:

spot temperature element; average temperature element; water bottom probe; pressure transmitters.

and to provide for an analog level output.

This option board has two HART channels:

HART input 1, standard used for the Enraf 762 VITO Interface; HART input 2, standard used for the connection of pressure transmitters for HIMS, HTG or vapour

pressure measurement.

Note 1:HTG: Hydrostatic Tank Gauging; only applicable with 877 FDI.HIMS is available with the level gauges (servo and radar).Vapour pressure measurement is mostly performed on pressurized vessels with the level gauges.

Note 2:Standard, the 762 VITO Interface is connected to HART input 1 and pressure transmitters are connected toHART input 2 of the optional HCU board.It must be verified that the maximum values for current and power of the HCU option board HART input 2circuit are not exceeding the maximum values of the connected HART pressure transmitters.If the values of HART input 2 circuit are too high, then connect the pressure transmitters to HART input 1 andthe 762 VITO Interface to HART input 2 (only possible when HART input 1 is available).

1.2 ICU_HPI board

The optional ICU_HPI board is used in Enraf 973 SmartRadar LT and 971 SmartRadar LTi to interface optionalequipment as:

spot temperature element; average temperature element; water bottom probe; pressure transmitters.

Note:Analog level output with the 971 and 973 SmartRadar LT(i) is provided by the optional ICU_HPO board.

For a description of these functions, refer to section 1.1.The ICU_HPI board has the same input functions as the HCU board; the only difference is its shape, whichmakes it to fit in the 971/973 SmartRadar LT(i).

Introduction


1.3 Overview of functions

The HCU / ICU_HPI option board has the following hardware channels:

SPOT input: for spot temperature element (RTD) Pt100 HART input 1: for 762 VITO Interface HART input 2: for HART pressure transmitters and/or external water bottom probe 4-20 mA output: for analog level output (only with HCU option board)

The hardware combinations, together with software emulations gives in total 8 different models according to thetable below:

Sales codefor option Function with HCU and ICU_HPI option board Emulation mode

B Spot temperature Pt100 TPU-2 / HSU

C VITO temperature and/or water probe HPU

J VITO temperature and/or water probe + HART device(s) HPUU Spot temperature + HART device(s) HSUV Analog level output MPU

W Analog level output + VITO temperature and/or water probe HCU

X Analog level output + VITO temperature probe MPU

Y HCUAnalog level output + Spot temperature Pt100 +VITO temperature and/or water probe + HART device(s)

Notes:1 Option codes: V, W and X are not available with the 970 / 971 / 973 SmartRadar types as the analog level

output is provided by the ICU_HPO option board.2 Please note that with option code Y in the 970 / 971 / 973 SmartRadar types, the analog level output is

provided by the ICU_HPO option board.3 Option code Y is not available in the 854 XTG servo gauge.4 Option code U can only be available in the 854 XTG servo gauge without connection for 977 TSI Tank

Side Indicator (in 854 ATG connection for 977 TSI is possible).5 HART devices can be: - HART pressure transmitters for HIMS / HTG configuration or vapour pressure

measurement; - HART water bottom sensor e.g. Side mounted water probe.

6 With sales code Y (all HCU functions), the spot temperature measurement is disabled if the VITOtemperature (and water) probe is present.

1.4 HCU compatibility

The HCU board can be used to replace an existing optional board in the 854, 873 and 877 gauges. However, itrequires some checking if more boards in the instrument must be updated or external equipment must bereplaced. The HCU board can be used to replace the following optional boards:

HPU board (for average temperature measurement, restricted to MTT or VITO probes only) HSU board (for spot temperature measurement, restricted to Pt100 RTDs only)

Note:Read carefully the installation guide of the HCU board before starting to replace the existing option board.

Introduction

Page 8

1.4.1 Replacement or adding optional board in 854 ATG or 854 XTG servo gauges

The HCU optional board requires an XPU-2 board in the 854 ATG and 854 XTG servo gauges. If there is noXPU-2 board installed, then the installed XPU (or XPU-1) board must be replaced by an XPU-2 board.

Notes:1 When the HCU board is used to replace an optional board with average temperature measurement,

please note the following:The 863 MRT with 862 MIR or the 864 MTT with 862 MIT temperature connection cannot be maintained. The 864 MTT can be connected to the 762 VITO Interface for connection to the HCU board; The 863 MRT cannot be connected to the 762 VITO Interface.

2 The optional data transmission channel on the XPU-2 (i.s. channel for 977 TSI or RS-232C/RS-485channel) is only possible when backplane-2 is installed. Backplane-2 is standard installed in instruments 854 ATG with series number: 854-20-400 and higher; 854 XTG with series number: 894-02-001 and higher.

1.4.2 Replacement or adding optional board in 873 SmartRadar

The HCU optional board can be installed in the 873 SmartRadar without any problem.Refer to Note 1 section 1.4.1.

1.4.3 Replacement or adding optional board in 877 FDI Field Display & Interface

The HCU optional board can be installed in an 877 FDI Field Display & Interface when there is an XPU or XPU-1board. However, be informed that water bottom measurement with the VITO probe or Side mounted water probeis not possible. If this function is required, then the installed XPU (or XPU-1) board must be replaced by anXPU-2 board. Refer to note 1 in section 1.4.1.

Note:The optional data transmission channel on the XPU-2 (i.s. channel for 977 TSI or RS-232C/RS-485 channel)is only possible when backplane-2 is installed. Backplane-2 is standard installed in indicators 877 FDI withseries number: 877-17-001 and higher.

1.5 Optional functions in this manual

This instruction manual describes the optional functions for:

HIMS (Hybrid Inventory Measurement) chapter 2 HTG (Hydrostatic Tank Gauging) chapter 3 Vapour pressure (P3) measurement chapter 4

The optional functions for temperature (spot and average) and water bottom measured and analog level outputare described in the instruction manual: Temperature, Water bottom and Analog output options.

Dens.obs. 'P7

Level & LP

1LG

[kg /m 3]

HIMS


Figure 2.1 Principle HIMS configuration

2 HIMS

2.1 Introduction into HIMS

The HIMS (Hybrid Inventory Management System) combines the direct mass measurement as used with HTG(Hydrostatic Tank Gauging) with the level gauge principle to one powerful system. All tank quantities as level,volume, mass, density, etc. can be measured and calculated.

For level measurement can be used the Enraf series 854 ATG / XTG servo gauge or the Enraf seriesSmartRadar gauge. The HIMS option is also available with the 877 FDI (Field Display & Interface).Pressure transmitters communicating with the HART protocol can be used.

2.1.1 HIMS calculations

The pressure transmitters P1 and P3 used with an HIMSsystem are of the differential type. That means one side(low pressure side) is open to atmosphere.P3 is not required for tanks which are free vented toatmosphere and with floating roof tanks.

A temperature measuring device is optional and onlyrequired when standard volume and reference density isto be calculated.

The pressure measured by P1 is the result of the staticliquid head above P1 (height h) and the pressure in thevapour space, measured by P3.

The liquid height above P1 is the level (l), measured bythe level gauge, minus the distance LP.LP represents the distance between the tank zero point(datum plate) and the zero point of P1.

The observed density is calculated as:

where:P7 : (P1 - P3) + corr. [Pa]P1 : pressure of pressure transmitter P1 [Pa]P3 : pressure of pressure transmitter P3 [Pa]corr. : for corrections, refer to section 2.1.2LP : distance zero point tank to zero point pressure transmitter P1 [m]LG : local gravity acceleration [m/s ]2Level : measured level from level gauge [m]

The measured level and (optionally) temperature, and the calculated observed density are transmitted to thetank gauging system.

The tank gauging system (an Enraf Entis system, Enraf CIUPlus or other host system) needs the Tank CapacityTable and optionally the ASTM table to calculate the Gross Observed Volume, Mass, and optionally the GrossStandard Volume and reference density.

HIMS

Page 10

2.1.2 Corrections for ambient air and vapour density

Ambient air density correction

The pressure at the atmospheric side measured by pressure transmitter P1, compared to P3, is increased by thecolumn of air over the distance (LM - LP). Refer to figure 2.1.

That is compensated in the calculated pressure P7 by the term:

(LM - LP) x RF x LG [Pa]where:

LM : distance zero point tank to zero point pressure transmitter P3 [m]LP : distance zero point tank to zero point pressure transmitter P1 [m]RF : ambient air density [kg/m ]3LG : local gravity acceleration [m/s ]2

The default value for the ambient air density (item RF) is set at 1.225 kg/m (floating point format).3

Vapour density correction

The vapour space above the product in a fixed roof tank consists of a mixture from air and product vapour.The density of this vapour mixture in the tank is different from the density of the air outside the tank.


(LM - Level) x RG x LG [Pa]where:

LM : distance zero point tank to zero point pressure transmitter P3 [m]Level : measured level from level gauge [m]RG : vapour density [kg/m ]3LG : local gravity acceleration [m/s ]2

The default value for the vapour density (item RG) is set at 1.25 kg/m (floating point format).3

Pressure P7

The pressure difference (P1 - P3), compensated for ambient air density and vapour density (item P7) iscalculated as:

P7 = (P1 - P3) + (LM - LP) x RF x LG - (LM - Level) x RG x LG [Pa]

Density in air

With the default values used in items RF and RG, the observed density is the density in vacuum. If the densityvalue is required as density in air, then item RF must be set to 0, and from item RG the value of the ambient airdensity must be subtracted.The table below summarizes the values for items RF and RG for density in vacuum and density in air.

HIMS density: in vacuum in air

ambient air density (item RF) 1.225 kg/m (default) 0 kg/m3 3

vapour density (item RG) 1.25 kg/m (default) (RG - ambient air density)3

HIMS


2.2 Commissioning of HIMS system

For information how to program items, refer to the instruction manual of the used level gauge or to the instructionmanual of the 847 Portable Enraf Terminal.

For connection of the pressure transmitters to the instrument, refer to the installation guide of the used levelgauge.

2.2.1 Selecting pressure and density dimension

When the pressure and/or density dimension has to be changed from default, all items with related formats haveto be changed and the values must be converted to the new dimension.

Note:When the instrument is equipped with the XPU-2 board, then all dimension depended items will beautomatically changed and the values will be automatically converted.

Item Name Description

W2= Protection level 2 Enter protection level 2

PI= Pressure dimension Selects the pressure dimension and converts the format.This item contains one character, which can be:

P : Pa; format: sign X X X X X X separator XK : kPa; format: sign X X X X separator X X XI : psi; format: sign X X separator X X X X XS : psi; format: sign X X X separator X X X X

Default set on: P [Pa]

DI= Density dimension Selects the density dimension and converts the format.This item contains one character, which can be:

K : kg/m ; format: sign X X X X X separator X X3A : API; format: sign X X X X separator X X XL : lbs/ft ; format: sign X X X separator X X X X3

Default set on: K [kg/m ]3

. .= format depended items Not required with XPU-2 board.Program all pressure depended and/or density depended items tothe new dimension. Refer to the table below for an overview ofthese items.

EX Exit Exit protection level.

Items from which the format depends Items from which the formaton the pressure dimension (item PI) depends on the density

dimension (item DI)

29 M1 O2 28 HDH1 M2 O3 DDH2 M3 P0 DLH3 O1 PH DU

HIMS

Page 12

Figure 2.1 Principle HIMS configuration

2.2.2 Tank and gauge data



LM= Distance P3 - tank zero Format according to item LD. This distance is used in tank gascorrection and ambient air density correction. If pressuretransmitter P3 is not installed, use a value equal to the upperreference point.Alternatively, use the value of item TT (with servo level gauges),or item PR (with SmartRadar gauges).

LN= Minimum HIMS level Format according to item LD. Default, item LN is set to 3.5metres.The distance LN can be lowered to approximately 2 metres.The purpose is of LN is as follows:If the level drops below the setting of LN, the last valid density willbe stored and used as the density value, as lower levels givesinaccurate density results.

LP= Distance P1 - tank zero Format according to item LD. The setting of item LP directlyinfluences the density calculation. It therefore must be assessedaccurately. Refer to Appendix B1 for some methods to assessthis distance.

HIMS


Continue:


PA= Available pressure transmitters Three characters; 123, or a - for the pressure transmitter whichis not installed. For HIMS, item PA can be:

1 - 3 : Pressure transmitters P1 and P3 are installed; or1 - - : Pressure transmitter P1 is installed.

LG= Local gravity Standard floating point format; units: m/s . Item LG must be set to2the local gravity constant. Appendix C gives information about thelocal gravity constant.

RF= Ambient air density Standard floating point format; units: kg/m . Default, RF is set to3+.12250000E+01. Refer to Appendix D for more information aboutthe ambient air density.

RG= Tank gas density Standard floating point format; units: kg/m . Default RG is set to3+.12500000E+01. Refer to Appendix E for more information aboutthe vapour density.

HT= HIMS / HTG selection One character; either I (for HIMS) or T (for HTG).Check if item HT is set to I; if not change it.

DL= Density lower limit Format according to item DI. Low density alarm set point.Default value: +00000.00 [kg/m ].3

DU= Density upper limit Format according to item DI. High density alarm set point.Default value: +00000.00 [kg/m ].3

HD= Density alarm hysteresis Format according to item DI. Hysteresis around the density lowerand density upper limits (items DL and DU).Default value: +00005.00 [kg/m ].3

M1= Minimum trip pressure P1 Format according to item PI. Sets a minimum trip pressure forpressure transmitter P1. Default value: +000000.0 [Pa].


H1= Maximum trip pressure P1 Format according to item PI. Sets a maximum trip pressure forpressure transmitter P1. Default value: +000000.0 [Pa].


PH= Pressure alarm hysteresis Format according to item PI. Hysteresis around the minimum andmaximum trip pressures (items M1, M3, H1 and H3).Default value: +000160.0 [Pa].


HIMS

Page 14

Figure 2.3 Tank shell bulging

2.2.3 Set-up and configuration of the pressure transmitters

For the Set-up and Configuration of the pressure transmitters with the HART Communicator refer to Appendix G.

2.2.4 Zero calibration of the pressure transmitters

For the zero calibration procedure of the pressure transmitters, refer to Appendix H.

2.2.5 Compensation for pressure transmitter P1 position

The tank shell will bulge due to the hydrostatic pressurecaused by the liquid stored in the tank.This can have an influence on the position of pressuretransmitter P1 (refer to figure 2.3).The amount of movement of pressure transmitter P1depends on the height of P1 above the bottom, thestructure of the tank shell and the density of the product.

In many cases, pressure transmitter P1 is located as lowas possible to the tank bottom and the influence of tankshell bulging is negligible.However, in those cases where the influence is present,items IF and IL can be used to compensate for theposition of pressure transmitter P1.Item IF (hydrostatic deformation factor) decreasesdistance LP for (IF) mm/m level above the level IL(hydrostatic deformation level). In formula:

LP = LP - (Level - IL) x IF [m]comp. progr.where:

LP : LP compensated for hydrostatic tank deformation [m]comp.LP : the programmed value for LP [m]progr.Level : measured level from level gauge [m]IL : hydrostatic deformation level (item IL) [m]IF : hydrostatic deformation factor (item IF) [mm/m]



IF= Hydrostatic deformation factor Standard floating point format; units: mm/m.Default value: +.00000000E+00. When left at the default value,the hydrostatic deformation compensation is disabled.Refer to Appendix F1 for information how to obtain a correctsetting for item IF.

IL= Hydrostatic deformation level Format according to item LD. Default value: +002.0000 [m].Item IL contains the level value above the hydrostatic deformationcompensation becomes effective. Refer to Appendix F1 how toobtain a correct setting for item IL.


HIMS


2.3 Operation

2.3.1 Display

For operation of the display and the information on it, refer to the instruction manual of the applicable level gauge(or 877 FDI). Below, only an overview is given which display formats give information about the pressure anddensity measurement.

Display format Displayed information

E HIMS density F Pressure P1 H Pressure P3

2.3.2 Manual inputs

For two quantities the operator can give a manual input by means of the PET (Portable Enraf Terminal), whichare not protected by protection level 1 or 2. These quantities are:


RJ= Manual tank gas density Standard floating point format; units: kg/m . The value must be3preceded by one status character:

V : Valid manual tank gas densityI : Invalid manual tank gas density

The tank gas density is used in the same way as with item RG.If the status of the manual tank gas density is valid (V), then themanual tank gas density (item RJ) is used.If the status of the manual tank gas density is invalid (I), then thevalue of item RG is used as tank gas density.

P0= Manual pressure P3 Format according to item PI. The value must be preceded by onestatus character:

V : Valid manual vapour pressureI : Invalid manual vapour pressure

If there is no P3 pressure transmitter installed, and the vapourpressure can be assumed constant, a manual vapour pressurevalue can be entered.

HIMS

Page 16

2.3.3 Data items

Below, a summary is given of available data items. They contain measured and calculated data, verification dataand error data.The verification data can be used to check the results of certain steps in the measuring sequence.The hydrostatic status indicates the validity of the measured / calculated data.The diagnostic data provides low level error information about the pressure measurement and densitycalculation.

There is only one operational command with HIMS.

Item Description

P1 Measured / Measured pressure of pressure transmitter P1P3 calculated data Measured pressure of pressure transmitter P3P4 P1 minus P3P7 (P1 - P3) compensated for ambient air density and vapour densityDQ Calculated HIMS density (preceded by 5 status characters of item QF)QQ Abbreviated HIMS density (preceded by 1 status character)N1 Serial number of pressure transmitter P1N3 Serial number of pressure transmitter P3Q1 Temperature of pressure transmitter P1 (if available)Q3 Temperature of pressure transmitter P3 (if available)QF Hydrostatic status request (refer to section 5.6)VV Verification data Refer to description at section 5.7

EH Diagnostic data Error HCU / ICU_HPI request (refer to section 5.5)FH Fatal HCU / ICU_HPI errorsH0 Last fatal HCU / ICU_HPI errorHE HART communication errors

Operational command:

SR Stop HART request (used with HART communicator).

Dens.obs. 'P1 & P2

LS

1LG

[kg /m 3]

Level ' P1 & P3P1 & P2

LS % LP [m]

Level ' P1 & P3Dens.obs.

1

LG% LP [m]

HTG


Figure 3.1 Principle HTG configuration

3 HTG

3.1 Introduction into HTG

An HTG (Hydrostatic Tank Gauge) system measures the tank quantities by means of pressure transmitters.Depending on the configuration, one to three pressure transmitters are required. The pressure transmitters,communicating with the HART protocol, are connected to an 877 FDI (Field Display & Interface).

Unlike level based tank gauges, as servo or radar, the HTG system is a direct mass measurement system.One pressure transmitter (P1), located at a shell nozzle near the bottom, is used to measure the liquid head.A second pressure transmitter (P2) is located approximately 2 to 2.5 metres (6 to 8 feet) above P1.If there exists a pressure in the vapour space, the vapour pressure must be measured with a separate pressuretransmitter (P3). P3 is not required on a floating roof tank, or with a free vented cone roof tank.

3.1.1 HTG calculations

The pressure transmitters used with an HTG system are of thedifferential type. That means one side (low pressure side) isopen to atmosphere.

A temperature measuring device is optional and only requiredwhen standard volume and reference density is to be calculated.

The principle HTG formulas for level and observed density are:

Observed density is calculated as:

Level is calculated as:

where:P1 : pressure of pressure transmitter P1 [Pa]P2 : pressure of pressure transmitter P2 [Pa]P3 : pressure of pressure transmitter P3 [Pa]LG : local gravity acceleration [m/s ]2LS : distance zero point pressure transmitter P1 to P2 [m]LP : distance zero point pressure transmitter P1 to zero point tank [m]

The calculated level and observed density and (optional) measured temperature are transmitted to the tankgauging system. The tank gauging system (an Enraf Entis system, Enraf CIUPlus or other host system) needsthe Tank Capacity Table and (optionally) the ASTM table to calculate the Mass, Gross Observed Volume, andoptionally the Gross Standard Volume and reference density.

When the product density is known and does not change, pressure transmitter P2 is not required. The densitywill be a manual input value, from which the level can be calculated by:

Gross Observed Volume ' MassDens.obs.

Mass ' (P1 & P3 ) Areaeq. 1LG % Vol.heel Dens.obs.

Mass ' P1 & P3P1 & P2

LS % LP & LP Areaeq. P1 & P2

LS

1LG

% Vol.heel Dens.obs.

Mass ' (P1 & P3 ) Areaeq. 1LG % Vol.heel Dens.obs.

HTG

Page 18

3.1.2 Volume and Mass calculations

The standard HTG mass and volume calculations are:

where:Vol. : Volume below the zero point of pressure transmitter P1 [m ]heel 3Area : Equivalent area over the (calculated) tank level [m ]eq. 2

Enraf transmits the calculated HTG level and observed density values to the tank gauging system (Entis,CIUPlus or other host system).In the tank gauging system the Gross Observed Volume is obtained from the level value via the tank capacitytable. Then Mass is calculated as:

Mass = Gross Observed Volume x Dens. obs.

This is equivalent to the standard HTG mass calculation as is shown in the following conversion equations:

Mass = Gross Observed Volume x Dens. obs.

Mass = (Level x Area ) x Dens.eq. obsMass = (Level - LP) x Area x Dens. + LP x Area x Dens.eq. obs. eq. obs.

substitute of HTG level and density formulas gives:

the above formula can be reduced to:

which is the standard HTG mass formula.

HTG


3.1.3 Corrections for ambient air and vapour density

Ambient air densityThe pressure at the atmospheric side measured by pressure transmitter P1, compared to P2 and to P3, isincreased by the column of air over respectively the distances LS and (LM - LP). Refer to figure 2.1.

That is compensated in the calculated pressures P7 and P8 by the terms:

(LM - LP) x RF x LG [Pa] for P7 (P1 - P3)

LS x RF x LG [Pa] for P8 (P1 - P2)

where:LM : distance zero point pressure transmitter P3 to zero point tank [m]LP : distance zero point pressure transmitter P1 to zero point tank [m]LS : distance zero point pressure transmitter P1 to P2 [m]RF : ambient air density [kg/m ]3LG : local gravity acceleration [m/s ]2

The default value for the ambient air density (item RF) is set at: 1.225 kg/m (floating point format).3

Vapour density correctionThe vapour space above the product in a fixed roof tank consists of a mixture from air and product vapour. Thedensity of this vapour mixture in the tank is different from the density of the air outside the tank.


(LM - Level) x RG x LG [Pa]

where:LM : distance zero point pressure transmitter P3 to zero point tank [m]Level : calculated HTG level (item HQ) [m]RG : vapour density [kg/m ]3LG : local gravity acceleration [m/s ]2

The default value for the vapour density (item RG) is set at: 1.25 kg/m (floating point format).3

Pressures P7 and P8The pressure differences (P1 - P3) and (P1 - P2), compensated for ambient air density and vapour density, are:

P7 = (P1 - P3) + (LM - LP) x RF x LG - (LM - Level) x RG x LG [Pa]

P8 = (P1 - P2) + LS x RF x LG [Pa]

DQ ' (P1 & P2 ) % LS RF LGLS LG

DQ ' P1 & P2LS

1

LG% RF

HQ ' (P1 & P3 ) % (LM & LP ) RF LG & (LM & HQ ) RG LG(P1 & P2 ) % RF LS LG LS %LP

HQ 'P1 & P3

LG% (LM & LP ) (RF & RG )

DQ & RG% LP

HTG

Page 20

Density calculationThe calculated density, corrected for ambient air density (item DQ) will then become:

Level calculationThe calculated level, corrected for ambient air density and vapour density (item HQ), becomes:

Item HQ is non-explicit. However, after conversion the level (item HQ) can directly be obtained:

Density in airWith the default values used in items RF and RG, the observed density is the density in vacuum.If the density value is required as density in air, then item RF must be set to 0, and from item RG the value of theambient air density must be subtracted.

The table below summarizes the values for items RF and RG for density in vacuum and density in air.

HTG density in vacuum in air

ambient air density (item RF) 1.225 kg/m (default) 0 kg/m3 3

vapour density (item RG) 1.25 kg/m (default) (RG - ambient air density)3

HTG


3.2 Commissioning

For information how to program items, refer to the instruction manual 877 FDI or to the instruction manual of the847 Portable Enraf Terminal. It is assumed that the basic settings for the 877 FDI are already programmed,according to the instruction manual 877 FDI.

For connection of the pressure transmitters to the instrument, refer to the installation guide 877 FDI.

3.2.1 Selecting pressure and density dimension

When the pressure and/or density dimension has to be changed from default, all items with related formats haveto be changed and the values must be converted to the new dimension.

Note:When the 877 FDI is equipped with the XPU-2 board, then all dimension depended items will be automaticallychanged and the values will be automatically converted.



PI= Pressure dimension Selects the pressure dimension and converts the format. Thisitem contains one character, which can be:



DI= Density dimension Selects the density dimension and converts the format. This itemcontains one character, which can be:

K : kg/m ; format: sign X X X X X separator X X3A : API; format: sign X X X X separator X X XL : lbs/ft ; format: sign X X X separator X X X X3

Default set on: K [kg/m ]3

. .= format depended items Not required with XPU-2 board.Program all pressure depended and/or density depended itemsto the new dimension. Refer to the table below for an overviewof these items.


Items from which the format depends Items from which the formaton the pressure dimension (item PI) depends on the density

dimension (item DI)

29 M1 O2 28 HDH1 M2 O3 DDH2 M3 P0 DLH3 O1 PH DU

Tankzero(datumplate)

P3

P1

P2

LNLS

LP

LM

HH HA

AH

LA LL

AH

HTG

Page 22

Figure 3.2 HTG tank data

3.2.2 Tank and gauge data



LM= Distance P3 - tank zero Format according to item LD. This distance is used in tank gascorrection and ambient air density correction. If pressuretransmitter P3 is not installed, use a value equal to the upperreference point.

LN= Minimum HTG level Format according to item LD. Default, item LN is set to 3.5metres.The distance LN can be lowered to a level which is approximately0.5 m (20") above the pressure transmitter P2.The purpose is of LN is as follows:If the level drops below the setting of LN, the last valid density willbe stored and used as the density value. This is, because as thelevel drops below P2, density cannot be calculated anymore.

LP= Distance P1 - tank zero Format according to item LD. The setting of item LP influencesthe level and hence the volume calculation. It therefore must beassessed accurately. Refer to Appendix B2 for some methods toassess this distance.

LS= Distance P1 - P2 Format according to item LD. The distance between pressuretransmitters P1 and P2 (item LS) is used in the level and densitycalculation. It can be directly measured by means of a measuringtape from flange to flange, or from the zero marks on bothpressure transmitters. Refer to Appendix B2 for some othermethods to assess this distance.

HTG


Continue:


PA= Available pressure transmitters Three characters; 123, or a - for the pressure transmitter whichis not installed. For example, item PA can be set to:

123 : Pressure transmitters P1, P2 and P3 are installed; or12 - : Pressure transmitters P1 and P2 are installed, etc.

LG= Local gravity Standard floating point format; units: m/s . Item LG must be set to2the local gravity constant. Appendix C gives information about thelocal gravity constant.

RF= Ambient air density Standard floating point format; units: kg/m . Default, RF is set to3+.12250000E+01. Refer to Appendix D for more information aboutthe ambient air density.

RG= Tank gas density Standard floating point format; units: kg/m . Default RG is set to3+.12500000E+01. Refer to Appendix E for more information aboutthe vapour density.

HT= HIMS / HTG selection One character; either I (for HIMS) or T (for HTG). Item HT must be set to: T.

OB= Optional board selection Three characters; selects the optional board. Must be set to: HPUfor the optional HCU and ICU_HPI boards.

IM= Indicator mode One character; selects the indicator mode of the 877 FDI.For HTG mode, item IM must be set to: H.

DL= Density lower limit Format according to item DI. Low density alarm set point.Default value: +00000.00 [kg/m ].3

DU= Density upper limit Format according to item DI. High density alarm set point.Default value: +00000.00 [kg/m ].3

HD= Density alarm hysteresis Format according to item DI. Hysteresis around the density lowerand density upper limits (items DL and DU).Default value: +00005.00 [kg/m ].3







HTG

Page 24

Continue:


PH= Pressure alarm hysteresis Format according to item PI. Hysteresis around the minimum andmaximum trip pressures (items M1, M2, M3, H1, H2 and H3).Default value: +000160.0 [Pa].

LU= Level status conversion One character; default: ? The character, specified in item LU, isused in the level status byte of the level record to the host toindicate a reduced level accuracy condition. Most Enraf tankgauging systems accept the ? character as reduced accuracystatus.With the following conditions, the contents of item LU is placed inthe level status:

manual or last valid P3 used; manual or last valid density used; manual gas density used; level below minimum HTG (item LN).


3.2.3 Alarm settings

Refer to figure 3.2. The high level alarm (HA) and low level alarm (LA) conditions are transmitted in the levelalarm byte of the level record to the host.



AH= Level alarm hysteresis Format according to item LD. Sets level alarm hysteresis.Default value: +000.1000 (m).

HA= High level alarm Format according to item LD. High level alarm set point.Default value: +026.0000 (m).

HH= High high level alarm Format according to item LD. High high level alarm set point.Default value: +026.1000 (m).

LA= Low level alarm Format according to item LD. Low level alarm set point.Default value: +002.0000 (m).

LL= Low low level alarm Format according to item LD. Low low level alarm set point.Default value: +001.9000 (m).


HTG


Figure 3.3 Upper reference value

3.2.4 Ullage readout

When an ullage reading is required, the two items shown below mustbe changed.The ullage value is also transmitted to the host via the two wire Enraffield bus.

The ullage, or outage, measurement is referred to a zero point at thetank top (upper reference point).The level, or innage, measurement is referred to a zero point at thetank bottom (datum plate).Refer to figure 3.3.

Note:The high and low level alarms are innage alarms.Hence, a high alarm condition occurs when there is a low ullageand visa verse.


W2= Protection level 2 Enter protection level 2.

UR= Upper reference Format according to item LD.Distance UR represents the distance from the innage zero point(datum plate) to the upper reference point at a dip hatch (or otherpoint at the tank top).

DE= Level type One character; either I or U.I : for innage measurement (default)U : for ullage measurement.


3.2.5 Set-up and configuration of the pressure transmitters

For the Set-up and Configuration of the pressure transmitters with the HART Communicator refer to Appendix G.

HTG

Page 26

Figure 3.4 Tank shell bulging

3.2.6 Zero calibration of the pressure transmitters

For the zero calibration procedure of the pressure transmitters, refer to Appendix H.

3.2.7 Compensation for pressure transmitter P1 - P2 distance

The tank shell will bulge due to the hydrostatic pressurecaused by the liquid stored in the tank. This can have aninfluence on the position of pressure transmitters P1 and P2(refer to figure 3.4). The amount of movement depends on theposition of P1 and P2, the length of the arm (nozzle - ballvalve), the structure of the tank shell and the density of theproduct. In some cases, the influence of the tank shell bulgingis negligible.

However, in those cases where the influence is present,several methods can be followed to limited the influence.

Mechanical solution: U-bend or rigid bar (refer toInstallation Info 003)

Compensation for the distance P1 - P2 (item LS).

This section describes how to compensate for the distance LS.

Item IF (hydrostatic deformation factor) increases distance LS for (IF) mm/m level above the level IL (hydrostaticdeformation level). In formula:

LS = LS + (Level - IL) x IF [m]comp. progr.where:

LS : LS compensated for hydrostatic tank deformation [m]comp.LS : the programmed value for LS [m]progr.Level : calculated HTG level (item HQ) [m]IL : hydrostatic deformation level [m]IF : hydrostatic deformation factor [mm/m]



IF= Hydrostatic deformation factor Standard floating point format; units: mm/m.Default value: +.00000000E+00. When left at the default value,the hydrostatic deformation compensation is disabled. Refer to Appendix F2 for information how to obtain a correctsetting for item IF.

IL= Hydrostatic deformation level Format according to item LD. Default value: +002.0000 [m]. Item IL contains the level value above which the hydrostaticdeformation compensation becomes effective.Refer to Appendix F2 for information how to obtain a correctsetting for item IL.

EX Exit Exit protection level

HTG


3.3 Operation

3.3.1 Display

For operation of the display and the information on it, refer to the instruction manual 877 FDI.Below, only an overview is given which display formats give information about the level, pressure and densitymeasurement.

Display format Displayed information

A HTG level and temperature B HTG level and status E HTG density F Pressure P1 G Pressure P2 H Pressure P3

3.3.2 Manual inputs

For three quantities the operator can give a manual input by means of the PET (Portable Enraf Terminal), whichare not protected by protection level 1 or 2. These quantities are:


RJ= Manual tank gas density Standard floating point format; units: kg/m . The value must be3preceded by one status character:

V : Valid manual tank gas densityI : Invalid manual tank gas density

The tank gas density is used in the same way as with item RG.If the status of the manual tank gas density is valid (V), then themanual tank gas density (item RJ) is used.If the status of the manual tank gas density is invalid (I), then thevalue of item RG is used as tank gas density.

P0= Manual pressure P3 Format according to item PI. The value must be preceded by onestatus character:


If there is no P3 pressure transmitter installed, and the vapourpressure can be assumed constant, a manual vapour pressurevalue can be entered.

DD= Manual density Format according to item DI. The value must be preceded by onestatus character:

V : Valid manual densityI : Invalid manual density

If there is no P2 pressure transmitter installed, and the productdensity can be assumed constant, a manual product density mustbe given.Note:

The manual density is the observed density.

HTG

Page 28

3.3.3 Data items

Below, a summary is given of available data items. They contain measured and calculated data, verification dataand error data.The verification data can be used to check the results of certain steps in the measuring sequence.The hydrostatic status indicates the validity of the measured / calculated data.The diagnostic data provides low level error information about the pressure measurement and densitycalculation.

There is only one operational command with HTG.

Item Description

P1 Measured / Measured pressure of pressure transmitter P1P2 calculated data Measured pressure of pressure transmitter P2P3 Measured pressure of pressure transmitter P3P4 P1 minus P3P5 P1 minus P2P7 (P1 - P3) compensated for ambient air density and vapour densityP8 (P1 - P2) compensated for ambient air densityDQ Calculated HTG density (preceded by 5 status characters from item QF)QQ Abbreviated HTG density (preceded by 1 status character)HQ Calculated HTG level (preceded by 5 status characters from item QF)VQ Calculated HTG ullage (preceded by 5 status characters from item QF)N1 Serial number of pressure transmitter P1N2 Serial number of pressure transmitter P2N3 Serial number of pressure transmitter P3Q1 Temperature of pressure transmitter P1 (if available)Q2 Temperature of pressure transmitter P2 (if available)Q3 Temperature of pressure transmitter P3 (if available)QF Hydrostatic status request (refer to section 5.6)VV Verification data Refer to description at section 5.7



SR Stop HART request (used with HART communicator).

Vapour pressure (P3) measurement


4 Vapour pressure (P3) measurement4.1 Introduction into vapour pressure measurement

The vapour pressure measured on spheres, spheroids, bullets, etc. is used in the calculation of the Total GrossStandard Volume. That is the volume which includes the amount of evaporated product in the vapour space.

The vapour pressure measurement can be integrated in the Enraf level gauge.The following level gauges can be equipped with an option board to measure the vapour pressure:

854 ATG servo gauge SmartRadar with high pressure antenna

Alternatively, the vapour pressure measurement can be connected to an 877 FDI (Field Display & interface) withan appropriate option board.

Pressure transmitters communicating with the HART protocol can be connected to the Enraf gauges with theoptional HCU or ICU_HPI board.

The measured pressure by the roof pressure transmitter (P3) is transmitted to the tank gauging system.The tank gauging system (an Enraf Entis system, Enraf CIUPlus or other host system) performs the correctionson the Gross Standard Volume and Mass for the amount of product in the vapour space.


Page 30

4.2 Commissioning

For information how to program items, refer to the instruction manual of the used level gauge or to the instructionmanual of the 847 PET (Portable Enraf Terminal).

For connection of the pressure transmitter to the instrument, refer to the installation guide of the used levelgauge.

4.2.1 Selecting pressure dimension

When the pressure dimension has to be changed from default, all items with a pressure format have to bechanged and the value must be converted to the new dimension.

Note:When the instrument is equipped with the XPU-2 board, then all dimension depended items will beautomatically changed and the values will be automatically converted.



PI= Pressure dimension Selects the pressure dimension and converts the format.This item contains one character, which can be:



. .= format depended items Not required with XPU-2 board.Program all pressure depended items to the new dimension.Refer to the table below for an overview of these items.


Items from which the format depends on the pressure dimension (item PI)

29 M1 O2H1 M2 O3H2 M3 P0H3 O1 PH



4.2.2 Gauge data



PA= Available pressure transmitters Three characters; 123, or a - for the pressure transmitter(s)which is (are) not installed. For vapour pressure measurement,item PA must be set to:

- - 3 : pressure transmitter P3 is installed

HT= HIMS / HTG selection One character; either I (for HIMS) or T (for HTG).Check if item HT is set to I; if not change it.



PH= Pressure alarm hysteresis Format according to item PI. Hysteresis around the minimum andmaximum trip pressure (items M3 and H3).Default value: +000160.0 [Pa]


4.2.3 Set-up and configuration of the pressure transmitter

For the Set-up and Configuration of the pressure transmitter with the HART Communicator refer to Appendix G.

4.2.4 Zero calibration of the pressure transmitter

For the zero calibration procedure of the pressure transmitter, refer to Appendix H.


Page 32

4.3 Operation

4.3.1 Display

For operation of the display and the information on it, refer to the instruction manual of the applicable instrument.The vapour pressure can be observed when Display format H is selected.

4.3.2 Manual input

If pressure transmitter P3 is temporary out of operation, a manual vapour pressure value can be given to theinstrument by means of the PET (Portable Enraf Terminal). The manual input is not protected by a password.


P0 = Manual pressure P3 Format according to item PI. The value must be preceded by onestatus character:


If the P3 pressure transmitter is temporary out of order, a manualvapour pressure value can be entered.

4.3.3 Data items

Below, a summary is given of available data items. There is only one operational command.

Item Description

P3 Measured data Measured pressure of pressure transmitter P3N3 Serial number of pressure transmitter P3Q3 Temperature of pressure transmitter P3 (if available)QF Hydrostatic status request (refer to section 5.6)VV Verification data Refer to description at section 5.7



SR Stop HART request (used with HART Communicator).

Maintenance and Troubleshooting


5 Maintenance and troubleshooting

5.1 Maintenance

For preventive maintenance on the pressure transmitters, refer to the maintenance instructions of the usedpressure transmitters.

It is recommended to check the zero calibration of the pressure transmitters once per year. Refer to Appendix H.

5.2 Troubleshooting HIMS

This section is intended as a help in finding the cause with start-up problems and when no correct reading of thepressure or density is obtained.

1) No or incorrect level reading.

Please refer to the section maintenance / trouble shooting of the instruction manual from the used levelgauge (servo or radar). An incorrect level reading results in a wrong volume reading and wrong densityreading, but mass remains unaffected.

2) No pressure value with items P1 and P3.

Check item PA (available pressure transmitters); Request for items EH and QF. Decode the displayed error codes as given in sections 5.5 and 5.6.

Find from the decoded message the cause of the problem; Check the wiring from the pressure transmitters to the instrument terminals (mind the polarity!); Check if the pressure transmitters are correctly configured (refer to Appendix G); Check the voltage on the instrument terminals for the pressure transmitter:

HART input 2 (recommended) HART input 1

Unloaded . 18.7 Vdc . 18.7 Vdc

1 transmitter . 16.4 Vdc . 15.9 Vdc

2 transmitters . 15.6 Vdc . 14.5 Vdc

The current on the HART communication line is obvious:- with 1 transmitter: 4 mA- with 2 transmitters: 8 mA

3) The HIMS observed density does not correspond with the real density from the product.

If the difference is 0.18%, then it can be explained from the method of pressure transmitter calibration.Some pressure transmitters are calibrated with water column at 20 C, while water has a density of 1000kg/m at 4 C. If this is the case, then correct item LG (local gravity) with 0.18%;3

Check zero calibration of pressure transmitters (refer to Appendix H); If there exists a density difference at mainly lower levels (thus not at higher levels), then the cause must

be found in a wrong value for item LP. Check on distance LP. Eventually check the level gauge on itscorrect reading;

If there is more or less a constant density difference, check on settings of items:LG, LM, RF, RG (or RJ).


Page 34

5.3 Troubleshooting HTG

This section is intended as a help in finding the cause with start-up problems and when no correct reading of themass, density, level, pressure or volume is obtained.

1) 877 FDI does not start-up correctly; no level / density indication. Please refer to the section service / trouble shooting of the instruction manual 877 FDI. Check items: IM, HT, OB and PA.

2) No pressure value with items P1, P2 and P3. Check item PA (available pressure transmitters); Request for items EH and QF. Decode the displayed error codes as given in sections 5.5 and 5.6.

Find from the decoded message the cause of the problem; Check the wiring from the pressure transmitters to the instrument terminals (mind the polarity!); Check if the pressure transmitters are correctly configured (refer to Appendix G); Check the voltage on the instrument terminals for the pressure transmitter:

HART input 2 (recommended) HART input 1

Unloaded . 18.7 Vdc . 18.7 Vdc

1 transmitter . 16.4 Vdc . 15.9 Vdc



The current on the HART communication line is obvious:- with 1 transmitter: 4 mA- with 2 transmitters: 8 mA- with 3 transmitters: 12 mA

3) The HTG mass value does not correspond with the real mass in the tank. If the deviation is more or less a constant offset value, and the level and observed density calculations are

correct, and the volume shows also an offset value, then the problem must be found in the strappingtables (incorrect data).

If the deviation is more or less a constant offset value, and the calculated level and volume shows asimilar offset, while the calculated observed density is correct, then item LP (distance P1 - tank zero)should be adjusted.

If the deviation is not a constant offset value, check pressure transmitters P1 and P3 (zero calibration).

4) The HTG calculated observed density does not correspond with the real density from the product. If the difference is 0.18%, then it can be explained from the method of pressure transmitter calibration.

Some pressure transmitters are calibrated with water column at 20 C, while water has a density of 1000kg/m at 4 C. If this is the case, then correct item LG (local gravity) with 0.18%;3

5) The HTG calculated observed density and calculated level (and hence, volume) are deviating from the realvalue. There is a situation in where the HTG system (which is a direct mass measurement system), cannot give

an accurate density, level and volume reading. That is the case when the product is stratified in density.Even when the product was homogeneous when it was loaded into the tank, it can become stratified asthe heavier parts in the product are settling down. The HTG system then measures a too high density, andhence level and volume are calculated too low. Mass however, is unaffected by stratification.

Check zero calibration of pressure transmitters (refer to Appendix H).



5.4 Troubleshooting vapour pressure (P3) measurementNo pressure value with item P3Refer to step 2 at section 5.3.

5.5 Hydrostatic error request (item EH)This item contains the most recent pressure transmitter error encountered by the optional HCU / ICU_HPI board.

xx00 No errorxx11 Pressure transmitter P1; no reply on initial HART Pressure transmitter P1 in fail or not connected; check with HART

commands communicator. Or when P1 is not installed: set first character ofitem PA to - (e.g. - - 3).

xx12 Pressure transmitter P2; no reply on initial HART Pressure transmitter P2 in fail or not connected; check with HARTcommands communicator. Or when P2 is not installed: set second character of

item PA to - (e.g. 1 - 3).xx13 Pressure transmitter P3; no reply on initial HART Pressure transmitter P3 in fail or not connected; check with HART

commands communicator. Or when P3 not installed: set third character ofitem PA to - (e.g. 1 - -).

xx35 Pressure transmitter P1; wrong PV dimension Primary Variable of pressure transmitter P1 must be set to: kPa.xx36 Pressure transmitter P2; wrong PV dimension Primary Variable of pressure transmitter P2 must be set to: kPa.xx37 Pressure transmitter P3; wrong PV dimension Primary Variable of pressure transmitter P3 must be set to: kPa.xx99 HART input option print not mounted Change HCU or ICU_HPI board for correct type.

xx: 24 for HPU emulation28 for HSU emulation30 for HCU emulation

5.6 Hydrostatic status request (item QF)The hydrostatic status request item contains five status bytes (Byte 0, Byte 1, Byte 2, Byte 3 and Byte 4) fromthe optional HCU / ICU_HPI board. For decoding, refer to the ASCII table in appendix A.

Status byte 0: Status byte 1:bit 0 : general HCU / ICU_HPI fail *) bit 0 : P1 exceeds min. or max. trip pressure

1 : low level alarm ) 1 : P2 exceeds min. or max. trip pressure12 : low low level alarm ) 2 : P3 exceeds min. or max. trip pressure *)13 : high level alarm ) 3 : exceeding range P114 : high high level alarm ) 4 : exceeding range P215 : level time-out ) 5 : exceeding range P3 *)26 : 1 6 : 17 : 0 7 : 0

Status byte 2: Status byte 3:bit 0 : fail P1 bit 0 : last valid density used

1 : fail P2 1 : manual density used2 : fail P3 *) 2 : high density alarm3 : manual P3 used *) 3 : low density alarm4 : last valid P3 used *) 4 : HTG level fail )15 : manual level used ) 5 : no previous store command *)26 : 1 6 : 17 : 0 7 : 0

Status byte 4:bit 0 : manual gas density used Note:

1 : level below LN Only the bits which are set to 1 have an active status.2 : last valid level used )23 : invalid level reading )24 : API underflow/overflow or negative density5 : 0 ) With HTG only; ignore these bits for HIMS.16 : 1 ) With HIMS only; ignore these bits for HTG.27 : 0 *) Use only these bits with vapour pressure measurement.


Page 36

5.7 HART device pointer (items VP and VV)By means of the value pointer (item VP) a vector can be loaded to the HCU or ICU_HPI option board. Next, withitem VV, the selected data is returned. Item VP consists of 4 positions, in the middle separated by a . or , :v w . x y (or v w , x y). The values for the value pointer are listed in the table together with the obtained data.

v w , x y Selected data Example / Dimension

0 0 , 0 0 HCU / ICU_HPI Emulation & Function VV=HCU HCAOMT- - PR

0 0 , 0 1 Configuration boot code VV=HCU CONFIG: 3F

0 0 , 0 2 HCU / ICU_HPI hardware version VV=HW VERSION: 00 0 0 , 0 3 Boot code software version VV=BOOTSW VERS:01

0 3 , 0 0 Error counters HART addresses 0, 1, 2 (for P1: counter 1, VV=0000:0000:0013

0 3 , 0 1 Error counters HART addresses 3, 4, 5 (for P3: counter 0) VV=0000:0000:0000 0 3 , 0 9 Detected HART device addresses (1 for P1; 2 for P2; VV=1 - 3 - 5 - - - - - - - - -

Emulation: HSU, HPU, HCUFunction: HC: HART channel installed

AO: analog outputST: spot temperatureMT: VITO average temperatureWS: external water bottom probeWT: VITO water bottom probePR: pressure transmitters

Sales code option: J boot code: 2EU 25Y 3F

for P2: counter 2)

3 for P3)


VP= HART device value pointer HART device value pointer; format: 2 digits, separator, 2 digits (refer to table above).

Example: VP=03.09: value pointer loaded to request thedetected HART devices

VV HART device pointer value HART device pointer value.This item holds the value requested by item VP (refer to tableabove).Example: the requested detected HART devices

Appendix


Appendix A ASCII table

Levelgauge

Level(1)TX-height(4)

LPTankzero

Roofdistance(3)

Ullage(2)

TX-centre(5)

H1H2

Roofdistance

Roofdistance=H1-H2

Appendix

Page 38

LP determination by measurement

Appendix B1 Assessment of distance LP for HIMS

In this Appendix three methods are described to obtain the distance: zero point tank - zero point pressure transmitter P1 (item LP).

B1.1 LP determination from measurement

The principle of this method consist of five measurements (refer to figure below). When performed well, the distance LP can be determinedwithin 2 mm.

Step 1) LevelThis is the level reading of the level gauge. Make sure it is indicating the correct value (level).

Step 2) UllagePerform a manual ullage measurement from a dip hatch located closed to the pressure transmitter P1 (ullage).

Step 3) Roof distanceThis is the distance from the selected dip hatch to a horizontal flat place on the tank railing above pressure transmitter P1(roof distance).We advise to measure this distance with a theodolite (optical measuring device), to bring over the horizontal distance fromthe levelled rod on the dip hatch to the levelled rod next to the tank railing.

Step 4) TX distanceMeasure the distance from the horizontal flat place on the tank railing to the top of the pressure transmitter flange(TX height).Use a measuring tape and perform this measurement at a time there is no (hard) wind.

Step 5) TX centreWith most pressure transmitters, the centre of the measuring diaphragm is also at the centre of the mounting flange(TX centre).For example: a 2", 150 lbs flange has a centre distance of 76.2 mm.

Calculate LP: LP = level + ullage + roof distance - TX height - TX centre

LP ' Level & P7LG Dens.obs.

120

110

100

90

80

70

60

50

40

30

20

10

0

-10 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Level[m]

regressionlinemeasureddata

Pres

sure

P7

[kP

a]

LP ' ConstantSlope

'4795.82

7539.795' 0.6361 [m]

Appendix


Linear regression method

B1.2 LP derived by calculation from density sample

This method is fast and easy, provided that the tank is filled for not more than half of its capacity and the product is homogeneous.LP can be found from the following formula:

where:Level : measured level from the level gauge [m]P7 : request for item P7 by means of the Portable Enraf Terminal [Pa]LG : request for item LG by means of the Portable Enraf Terminal [m/s ]2Dens. : this is the value from a manual density sample. [kg/m ]obs. 3

Note: If the density value is provided by the lab, make sure it is re-calculated

to the observed density value at the actual product temperature.

B1.3 LP determined by linear regression

With this method a number of readings are taken over the full measuring range. The readings taken are: Level and P7.

Note:This method can only be followed when the product is homogeneous.Hence for products with density stratification, this method cannot be used.

The measurements can only be taken with the same product. In practice this means, one start with a full tank and take the readings after abatch is dispatched. A set of at least 8 to 10 measurement over the measuring range should be taken to get a good result. It can take severaldays before the measurements are completed.

Request the Level from the level gauge and request for P7 by means of the Portable Enraf Terminal (item P7).At the end of the test run, all gathered data can be processed in a spread sheet program to calculate the pressure regression line.Where the regression line of the pressure value crosses the zero line of the pressure-axis, the corresponding level value on the level-axisrepresents the distance LP.

As an example, the following Level and P7 values aretaken, and the figure shows the regression line.

Level P7 [m] [Pa]

15.755 114000.514.582 105134.413.290 95421.811.563 82402.510.051 70963.2 8.491 59198.0 7.327 50480.1 5.272 34968.4 4.783 31250.6 3.149 18932.9 2.385 13192.7 1.234 4515.3

Distance LP can be calculated from the regression data:

Level(1)TX-height(4)

LPTankzero

Roofdistance(3)

Ullage(2)

TX-centre(5)

H1H2

Roofdistance

Roofdistance=H1-H2

Appendix

Page 40

LP determination by measurement

Appendix B2 Assessment of distance LP (and LS) for HTGIn this Appendix three methods are described to obtain the distance: zero point tank - zero point pressure transmitter P1 (item LP).

B2.1 LP determination from measurement

The principle of this method consist of five measurements (refer to figure below). When performed well, the distance LP can be determinedwithin 2 mm.

Step 1) LevelThe level can be taken from an innage dip at the datum plate, or from a manual ullage measurement at the upper referencepoint. Take the level reading (level).

Step 2) UllagePerform a manual ullage measurement from a dip hatch located closed to the pressure transmitter P1 (ullage).

Step 3) Roof distanceThis is the distance from the selected dip hatch to a horizontal flat place on the tank railing above pressure transmitterP1(roof distance).We advise to measure this distance with a theodolite (optical measuring device), to bring over the horizontal distance fromthe levelled rod on the dip hatch to the levelled rod next to the tank railing.

Step 4) TX distanceMeasure the distance from the horizontal flat place on the tank railing to the top of the pressure transmitter flange(TX height).Use a measuring tape and perform this measurement at a time there is no (hard) wind.

Step 5) TX centreWith most pressure transmitters, the centre of the measuring diaphragm is also at the centre of the mounting flange(TX centre).For example: a 2", 150 lbs flange has a centre distance of 76.2 mm.

Calculate LP: LP = level + ullage + roof distance - TX height - TX centre

Level ' P1 & P3P1 & P2

LS % LP

Appendix


B2.2 LP derived from mass calculation

As the HTG system is a direct mass measuring system, it is obvious to calibrate the HTG system by means of a mass comparison method.First of all, a good guess is made for the distance LP. In the worst case, LP can be left at zero.The mass of the product in the tank, measured by the HTG system, will be compared with the mass, measured and calculated in thetraditional way or by means of another mass measuring system (such as mass-flow meters).

Note:Before applying this method the density measurement (and thus distance LS) must be correct, as the density is used in the heel mass.

The traditional way is:

manual dip (or ullage dip from URP, then convert to innage) find volume in tank capacity table measure the temperature from the product perform a density sample calculate the reference density calculate the standard volume calculate mass as standard volume times reference density

The outcome from this mass calculation (or from another mass measuring device) is then compared to the mass reading of the HTG system.Find distance LP with a trial and error method.

B2.3 LP (and LS) determined by linear regressionWith this method a number of level readings are taken over the full measuring range. The level reading from the HTG system and the levelreading from a manual measurement are compared.

Note:Although the HTG system is a direct mass measurement system, the calibration described below is based on level measurement. Thelevel measurement from an HTG system is not that accurate that it can be used in a calibration method for a mass measurement system.The reason that this method is described, is that it is a relative simple method. In general we do not recommend this method.

Note:This method can only be followed when the product is homogeneous.Hence for products with density stratification, this method cannot be used.

Recall the basic HTG level formula:

An error in the distance LS will cause a gain error in the HTG level reading, andan error in the distance LP will cause an offset error in the HTG level reading.Take a good guess for the values of items LP and LS.

The measurements can only be taken with the same product. In practice this means, one start with a full tank and take the readings after abatch is dispatched. A set of at least 8 to 10 measurement over the measuring range should be taken to get a good result. It can take severaldays before the measurements are completed. At the end of the test run, all gathered data can be processed in a spread sheet program.

As an example, the following level data is taken:(LP=+000.7500 m and LS=+002.1000 m)

Manual HTG Delta Regression data From the level difference (defined as: Manual level - HTG level level level from level difference level), a regression line is calculated. From this regression [m] [m] [mm] (against manual level) line data, correction factors can be obtained for the

distances LP and LS.17.238 16.7998 438.2 Constant: 0.014946 m15.755 15.4041 350.9 Slope: 0.024347 m/m The first approximation for the correction factor for LP is:14.582 14.2574 324.6 LP = Constant + Slope x LPcorr.13.290 12.9826 307.411.563 11.3063 256.7 A second (and perhaps third) recalculation may be required10.051 9.8184 232.6 to find the proper correction factor for LP: 8.491 8.3102 180.8 LP = Constant + Slope x (LP + LP )corr. corr. 7.327 7.1500 177.0 5.272 5.1616 110.4 The recalculation can be terminated when the difference 4.783 4.6730 110.0 between the last correction factor and the one before the

last one is 0.0015 m. Distance LP then becomes:LP = LP + LPcorr

LS ' P8Dens.obs. LG

Appendix

Page 42

The first approximation for the correction factor for LS is: correction on LP correction on LS

LS = Slope x LS LPcorr. 0.003314 LScorr. 0.051128corr.

A second (and perhaps third) recalculation may be required: LPcorr. 0.000081 LScorr. 0.001245LPcorr. 0.003395 LScorr. 0.052373

LS = Slope x (LS + LS ) LP 0.7534 LS 2.1524corr. corr.

The recalculation can be terminated when the differencebetween the last correction factor and the one before thelast one is 0.0015 m. Distance LS then becomes:

LS = LS + LScorr.

The table at the right upper corner shows the calculationresults for the example and the figure shows (a part) ofthe regression line with the relevant data used in thiscalculation example.

B2.4 LS derived from calculation of density sampleThe distance LS can be calculated from a known density (taken by a sample) and the pressure value P8. The HTG density formula can bere-arranged to calculate the distance LS:

All data are measured when the level in the tank is not moving and mixers are shut off. To perform density sampling, a dip hatch must beopened, and time should be given to vent eventually over pressure and to stabilize the pressure readings.

P8 : The pressure P8 is read by means of the PET (Portable Enraf Terminal). Take more than one reading with a sufficient timeinterval (for instance: 5 readings with an interval of one minute each). Average the readings.

LG : The value of item LG can also be requested by the PET or copied from the Set-up/Maintenance form or log-file of the 877FDI.

Dens. : This is the value from the manual density sample which must be taken.obs.The best place to take the density sample is as close as possible to the place where the pressure transmitters P1 and P2 areinstalled. The samples can only be taken over the height between pressure transmitters P1 and P2. Make sure the densitysample is an average density sample over this height.Since the density required is an observed density value, the product temperature must be measured as well.If from Lab analyses a reference density is provided, recalculate it to the observed density value.

Note:Mind to take the same type of density in the HTG and sample: density in air or density in vacuum.

0 10 20 30 40 50 60 70 80 90

9.84

9.83

9.82

9.81

9.80

9.79

9.78

9.77

9.8128

Latitude []

grav

itya

cce

lera

tion

[m/s

]2

52.2

Appendix


Gravity acceleration graph (for sea level)

Appendix C Local gravity constant (item LG)The gravitational acceleration constant is not the same all over the world and depends on the latitude and height above sea level.

The table and graph below gives an approximate gravity acceleration for several ellipsoidal latitudes at sea level.

Latitude [] g [m/s ] Latitude [] g [m/s ] Latitude [] g [m/s ]2 2 2

0 9.780490 30 9.793378 60 9.819239

5 9.780881 35 9.797455 65 9.822941

10 9.782043 40 9.801805 70 9.826139

15 9.783940 45 9.806294 75 9.828734

20 9.786517 50 9.810786 80 9.830647

25 9.789694 55 9.815146 85 9.831819

The following term must be added to the gravity figure from the table and graph for correction above sea level:

- 0.003086 [m/s /km]2

-20 -10 0 10 20 30 40 50

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0 m

500 m

1000 m

1500 m

1.218

Airdensityatdifferentheights

with80%humidity(@1013mbar)

averageambienttemperature[C]

15

am

bie

nt

air

den

sit

y(R

F)

[kg

/m]

3

Appendix

Page 44

Ambient air density

Appendix D Ambient air density (item RF)The barometric pressure decreases with the height above sea level. If for the average barometric pressure at sea level is taken 1013 mbar,then the barometric pressure at different heights is given as:

Height above sea [m] Barometric pressure [m]

0 1013

500 955

1000 899

1500 846

The graph below gives the air density at different temperatures and different heights above sea level according to the barometric pressuregiven in the table above.

Select for item RF a value, according to the height above sea and the average ambient temperature throughout the year.

For example: Netherlands; a country at sea level height; average barometric pressure: 1013 mbar; average day-time temperature: 15 C.Then, for the ambient air density, a value of 1.218 kg/m is found.3

Density in air

With the true value of the ambient air density used in item RF, the product density is calculated as density in vacuum.If the product density is required as density in air, then item RF must be set to 0. Refer also to appendix E.

Dens.gas mix '0.012027273.15 % T

(Pvap. Mliq.

hims_htg & vapor pressure (p3) measurement_4416645_rev1[1]

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