Micro Motion Manual: Liquid Density Meter Standard and Advanced Electronics - Model 7835, 7845, 7846, 7847 | Micro Motion Manuals & Guides

®

Technical Manual

78355080_US, Rev. D
December 2008

7835/7845/7846/7847

Micro Motion

7835/7845/7846/7847 Liquid Density Meter

Standard and Advanced
Electronics

Contents 7835/45/46/47 Technical Manual

Copyright ¤ 200

Micro Motion

®

pursues a policy of continuous development and product improvement. The specification in this document

may therefore be changed without notice. To the best of our knowledge, the information contained in this document is

accurate and Micro Motion

No part of this document may be photocopied or reproduced without prior written consent of Micro Motion

®

cannot be held responsible for any errors, omissions or other misinformation contained herein.

®

.

Cont-2

7835/45/46/47 Technical Manual Contents

IMPORTANT NOTICE

DO NOT drop the meter. Handle with care.

DO NOT use liquids incompatible with the MATERIALS OF CONSTRUCTIONS.

DO NOT position RUPTURE DISC where failure could cause personal injury.

DO NOT allow axial loading from PIPEWORK STRESSES to exceed ½ TONNE.

DO NOT operate the meter above its RATED PRESSURE.

DO NOT PRESSURE TEST above the specified TEST PRESSURE.

DO NOT expose the meter to excessive vibration (of >0.5g continuous).

ENSURE all ELECTRICAL SAFETY requirements are applied.

ENSURE meter and associated pipework are PRESSURE TESTED to 1½ times the

maximum operating pressure after installation.

ENSURE meter is not TRANSPORTED when it contains hazardous fluids. This
includes fluids that may have leaked into, and are still contained, within the case.
Returns Forms are included as Appendix J.

Cont-3

Contents 7835/45/46/47 Technical Manual

Contents

Chapter 1 Introduction

1.1 About this manual ......................................................................................................................1-1

1.2 Product Overview.......................................................................................................................1-2

1.3 Meter Product Range .................................................................................................................1-2

1.4 Electronics Product Range........................................................................................................1-3

1.5 Advanced Electronics................................................................................................................1-4

---- Part Number Identification tables for 7835, 7845, 7846 and 7847 ..........................................1-5

Chapter 2 Mechanical Installation

2.1 General ........................................................................................................................................2-1

2.2 Planning an installation .............................................................................................................2-2

2.3 Meter mounting and pipework ..................................................................................................2-3

2.4 Pressure drop in the meter........................................................................................................ 2-6

2.5 Special considerations for hygienic applications ...................................................................2-7

2.6 Post-installation checks ............................................................................................................2-7

Chapter 3 Advanced Unit Electrical Installation and Configuration

3.1 General ........................................................................................................................................3-1

3.2 Planning an electrical installation.............................................................................................3-2

3.3 Electrical installation in safe areas...........................................................................................3-3

3.4 Electrical installation in hazardous areas ................................................................................3-6

3.5 Baseboard configuration ...........................................................................................................3-8

3.6 Baseboard plus HART

3.7 Advanced density post-Installation checks...........................................................................3-10

®

option board.......................................................................................3-9

Chapter 4 Standard Density Unit Electrical Installation

4.1 General ........................................................................................................................................4-1

4.2 Ground connections ..................................................................................................................4-1

4.3 Use with Flow Computers and Signal Converters...................................................................4-1

4.4 Use with customer’s own equipment .......................................................................................4-2

4.5 Post-installation checks ............................................................................................................4-4

Chapter 5 Entrained Gas Electronics Electrical Installation

5.1 General ........................................................................................................................................5-1

5.2 Ground connections ..................................................................................................................5-1

5.3 Use with Flow Computers and Signal Converters...................................................................5-1

5.4 Use with customer’s own equipment .......................................................................................5-2

5.5 Post-installation checks ............................................................................................................5-3

Chapter 6 Calibration and Performance

6.1 General ........................................................................................................................................6-1

6.2 Interpretation of calibration certificate.....................................................................................6-1

6.3 Calibration...................................................................................................................................6-7

6.4 Performance .............................................................................................................................6-10

Cont-4

7835/45/46/47 Technical Manual Contents

Contents

Chapter 7 Remote Display and Digital Communications

7.1 Introduction ..........................................................................................................................7-1

7.2 Mechanical installation of the 7965 Remote Display......................................................... 7-2

7.3 Safe area electrical installation ........................................................................................... 7-3

7.4 Hazardous area electrical installation ................................................................................ 7-3

7.5 Configuring the baseboard using a Remote Display ........................................................7-4

7.6 Multi-drop installation.......................................................................................................... 7-8

7.7 Electrical installation of computer devices........................................................................ 7-9

Chapter 8 General Maintenance

8.1 General .................................................................................................................................. 8-1

8.2 Fault Analysis ....................................................................................................................... 8-1

8.3 General Maintenance Procedure......................................................................................... 8-1

Chapter 9 Using Adview

9.1 What is Adview?................................................................................................................... 9-1

9.2 Installing Adview .................................................................................................................. 9-1

9.3 Starting Adview .................................................................................................................... 9-2

9.4 Using Adview........................................................................................................................ 9-5

Appendix A 7835 Specification

A.1 Performance.........................................................................................................................A-1

A.2 Mechanical ...........................................................................................................................A-1

A.3 The 7835 meter versions .....................................................................................................A-2

A.4 Safety approvals ..................................................................................................................A-2

Appendix B 7845/46/47 Specification

B.1 Performance.........................................................................................................................B-1

B.2 Mechanical ...........................................................................................................................B-2

B.3 7845/46/47 Meter Versions ..................................................................................................B-2

B.4 Safety Approvals..................................................................................................................B-4

Appendix C 7845/47 Entrained Gas Specification

C.1 Performance.........................................................................................................................C-1

C.2 Mechanical ...........................................................................................................................C-2

C.3 7845/47 meter versions .......................................................................................................C-2

C.4 Safety approvals ..................................................................................................................C-2

Appendix D Electronics Specifications

D.1 Standard electronics ...........................................................................................................D-1

D.2 Standard entrained gas electronics ...................................................................................D-1

D.3 Advanced electronics..........................................................................................................D-1

D.4 Environmental performance ...............................................................................................D-2

Cont-5

Contents 7835/45/46/47 Technical Manual

Contents

Appendix E Baseboard Calculations and Configurable Factors

E.1 Baseboard configuration.................................................................................................... E-1

E.2 Baseboard diagnostics ....................................................................................................... E-4

E.3 Baseboard calculations ...................................................................................................... E-5

Appendix F Specimen Calibration Certificates

Appendix G Conversion Tables and Product Data

G.1 Conversion tables............................................................................................................... G-1

G.2 Product data ........................................................................................................................G-4

Appendix H Modbus Communications

H.1 Introduction ......................................................................................................................... H-1

H.2 Outline of Modbus communications ................................................................................. H-1

H.3 Modbus dialect .................................................................................................................... H-2

H.4 Establishing Modbus communications............................................................................. H-3

H.5 Modbus commands............................................................................................................. H-4

H.6 Modbus register assignments ........................................................................................... H-4

H.7 Index and enumeration codes............................................................................................ H-7

Appendix I HART® Software

I.1 Introduction.............................................................................................................................I-1

I.2 HART

I.3 Electrical installation..............................................................................................................I-3

I.4 HART

I.5 Transmitter specific command structure .............................................................................I-7

I.6 Summary of HART

®

basics..........................................................................................................................I-1

®

commands ..................................................................................................................I-4

®

functionality ........................................................................................I-10

Appendix J Returns Forms

Appendix K Certified System Drawings

Cont-6

7835/45/46/47 Technical Manual Introduction

Chapter 1

Introduction

1.1 About this manual

This manual covers the complete range of Micro Motion® 7835/45/46/47 Liquid Density Meters and the various electronics
configurations available.

From the schematic diagram below, you can see which of the chapters in this manual refer to the part icular instrument
that you have. The remaini ng chapters can be placed at the back or removed from the manual.

Advanced Electronics

Standard Electronics Entrained Gas Electronics

Chapter 1

HART OPTION

2
3

6

8

Chapter 1

7835/45/46/47
LIQUID DENSITY METER

2

4

6

8

ENTRAINED GAS AMPLIFIERSTANDARD AMPLIFIERADVANCED BASEBOARD

Chapter 1

2

5
6

8

REMOTE
DISPLAY

CONTENTS

Chapter 1: Introduction
Chapter 2: Mechanical Installation
Chapter 3: Advanced Unit Electrical

Chapter 4: Standard Unit

Chapter 5: Entrained Gas Unit

Chapter 6: Calibration & Performance
Chapter 7: 7965 Remote Display & Digital

Chapter 8: General Maintenance
Chapter 9: Using Adview

Installation & Configuration

Electrical Install ation

Electrical Install ation

Communications

Meter Mechanics

Chapter 1

2

6

8

7965 Remote Display

Chapter 1

2
3

6
7
8

Figure 1.1

Page 1-1

Introduction 7835/45/46/47 Technical Manual

1.2 Product Overview

All of the products consist of a mechanical meter and an electronics unit that is normally mounted inside the meter
electronics housing. Together, the electronics and meter provide a system for continuous on-line measurement of
liquid density and temperature.

In applications where the pipeline te mp era ture could exceed 110°C (230°F), the electronics should be mounted in a
Remote Amplifier Box (see Chapters 3 and 4 for more details.)

Electronics Enclosure

transducers

Meter

Figure 1.2

Liquid density is determi ned from the resonant freque ncy of a vibrating tube containing the liquid, and liquid temperature
is determined from a 100 Platinum Resistance Thermometer (PRT). For information on the calculation of density and
temperature, please refer to Chapter 6 and Appendix G respectively.

1.3 Meter Product Range

The meters are identical m echanically, except for the material used in the wetted parts and the flanges/couplings. A fully
welded design is utilised to ensure maximum reliability in the most severe environments. A rupture disc is embodied in the
meter end plate furthest from the amplifier housing. This disc will rupture if a pressure build-up occurs within the case, in the
unlikely event of a tube assembly leak; the operation of the rupture disc is shown in Figure 2.2.

The range of meters is ou tlined below. For furt her details, please refer to Appendices A to C.

Meter Tube material Features

7835 NI-SPAN-C® Low temperature coeffi ci en t and long te rm sta bi li ty , appr op riate fo r fisc al

7845 316L Stainless

steel

applications.

Good resistance to corrosion.

7846 Alloy C22 Very high resistance to corrosion.

7847 316L Stainless

steel

Designed for the hygiene requireme nts of th e food pro c es sing in dus t ry and has
“3A’s” authorisation. Please refer to Section 2.4 for special cleaning and
installation requirem ent s in hygi en i c appl i cat ion s .

Page 1-2

7835/45/46/47 Technical Manual Introduction

1.4 Electronics Product Range

The meters described above may be operated with any of the following electronics options. However, the electronics
options are not
the Standard electronics boards, and so only fit in the extended electronics enclosures provided with an Advanced meter.

It should be noted that the Standard Entrained Gas Electronics are NOT suitable for operation in hazardous areas,
whereas all of the other electronics boards are suitable.

For further details of th e performance of the different electronics boards, please refer to the appropriate chapters and
Appendices D and E.

Standard
Electronics

Density
version

Entrained
gas version

all directly interchangeable; this is because the Advanced electronics boards are physically longer than

Table 1.1

Basic amplifier circuit providing a frequency signal (indicating liquid
density) and PRT resistance (indicating liquid temperature). Interfaces
with a Signal Converter or Flow Computer.

Similar amplifier circuit to the above but meter operating at a lo wer
frequency which is more insensitive to entrained gas. It is NOT suitable
for operation in hazardous areas.

Advanced
Electronics

Density
version

Entrained
gas version

Remote Amplifier Box

Advanced
Electronics

Microprocessor control led circuit with a choice of analogue and digital
outputs providing a direct measurement of density and temperature. Also
providing a selection of calculated parameters and several diagnostic
functions.

As above but meter operating at a lower frequency more appropriate for
liquids with entrained gas. Suitable for operation in hazardous areas.

Suitable for operation in hazardous areas.
784521A: IIB Approval (ATEX)

784522A: IIC Approval (ATEX)
784523A: CSA Approval
784524A: Non-classified (supplied as spare for customer installation).

Note that the advanced electronics’ amplifier cannot be fitted into the
Standard electronics’ Remote Amplifier Box.

Page 1-3

Introduction 7835/45/46/47 Technical Manual

1.5 Advanced Electronics

In contrast to a meter fitted with Standard electronics (which requires a Flow computer or Signal Co nverter for
operation), the meter with Advanced electronics will provide a complete measurement system.

An Advanced Baseboard plus meter provides a complete system for measuring liqui d densi ty and liquid temperature. A
Remote Display or one of the optional boards may be required if outputs need to be configured in the field o r if additional
functionality is required.

For convenience, the Adva nced system design and performance are outlined below ; full performance specifications are
given in Appendices D and E.

Option board

Remote Display

7965 DISPLAY

Baseboard

Figure 1.3

1.5.1 Baseboard

The Baseboard can be considered the heart of the system. Along with a liquid density meter, it provides a complete
system for measuring liqu id density and liquid temperature. The Baseboard performs a range of useful calculations and
provides the follow ing outputs:

 Two fully configurable 4-20mA outputs.
 One pulse output providing either an alarm status signal or the meter tube frequency.
 An RS485 digital communications link using RTU Modbus protocol.

1.5.2 Option board

The option board fits directly onto the Baseboard. One option board is presently available:

®

 HART

Only one board may be fitted at a time.

board - providing an additional 4-20mA output and full HART® communications.

1.5.3 Remote Display

The 7965 Remote Display unit is intended for either hand-held or wall-mounted use. It provides a convenient means for
displaying calculated data and for con f ig uring or analysing the system set-up. It communicates via th e Base bo ar d RS48 5
digital communication link. One remote display can communicate with a number of meters if they are connected together
on the same RS485 link. Further details of the 7965 Display are given in Chapter 7.

Page 1-4

7835/45/46/47 Technical Manual Introduction

PART NUMBER IDENTIFICATION FOR 7835

Code Product

7835

NI-SPAN-C

A 1” ANSI 900 RF
B 1” ANSI 600 RF
D 1” ANSI 600 RTJ
E 1” ANSI 900 RTJ
F 1” ANSI 600 RF Smooth Face
H 25mm DIN 2635 DN25/PN40
J 25mm DIN 2635/2512 GVD DN25/PN40
L 25mm DIN 2637 RF DN25/PN100
Z Special

A
E
F

A Standard Stainless Steel for tube, mounted ampl ifier or remote amplifier.
B Outer containment (1/4 NPT), stainless ste el for tube , mount ed amp lifiers o r remote amplifie r.
C Secondary containment B31.3 (1/2 NPT) for tube, mounted amplifier or remote amplifier (100Bar)

F Tube mounted flat box in stainless steel.

A Std frequency out, EEx ia IIC T4 (-4 0°C…+40°C) or T4 (-40 °C…+70°C)
B Advanced board: 2 x 4-20mA outputs, EEx ia IIC T4 (-40°C…+60°C)
D

Code Safety Approval and Label
J ATEX intrinsically safe (see “On-board Electronics” for rating)

L CSA intrinsically safe (Canada and USA)

A API Degrees (Americas) – Advanced board only.
B Base density to API tables (Metric) – Advanced only.
C Line density only – Advanced board only.
D General process incl. matrix (user data) – Advanc’d only.
T Frequency version – no software to configure.
Z Special

A Instrument standard.
D UKAS calibration (water).
E UKAS calibrati on (3 liquids).
Z Special
Code ASME IX

A None.
B Dye penetratio n (internal welds)
C Dye penetration (all welds)
D Radiography of flange welds + B
E Radiography of flange welds + C
F Radiography of flange welds

A None
X Certificates of material

7835 A A A F B J B A A A

Code Process Connect ions

®

Liquid Density Meter

Code Material Options

Wetted parts: Ni-Span
Wetted parts: Ni-Span
Wetted parts: Ni-Span

Code Meter Outer Containment

Code Amplifier Enclosure

®

tube, S.S. bellows and input, S.S. outer case

®

tube, S.S. bellows and input, Hastelloy® outer case

®

tube, S.S. bellows and input, Duplex outer case

Code On-board Electronics

®

Advanced board: HART

Code Default Configuration

, 3 x 4-20mA outputs, EEx ia IIB T4 (-40°C… +60°C)

Code Calibration

Code Traceability

(Typical Code)

Page 1-5

Introduction 7835/45/46/47 Technical Manual

PART NUMBER IDENTIFICATION FOR 7845

Code Product

7845 316L STAINLESS STE EL L iqu i d Densi t y Mete r

C 1” ANSI 300 RF
K 1” ANSI 600 RF
H 25mm DIN 2635 DN25/PN40
J 25mm DIN 2635/2512 GVD DN25/PN40
L 25mm DIN 2637 RF DN25/PN100
Z Special

B Wetted parts: 316L Stainless Steel, 316L Stainless Steel outer case
D Wetted parts: Alloy C22 bellows, 316L Stainless Steel tube, flanges and outer case. NACE.

A Standard Stainless Steel for tube, mounted amplifier or remote amplifier.
B Outer containment (1/4 NPT), stainless steel for tube, mount ed ampl ifiers o r remote ampli fier.
C Secondary containment B31.3 (1 /2 NPT) for tube, mounted amplifier or remote amplifier (100Bar)

F Tube mounted flat box in stainless steel.
Code On-board Electronics
A Std frequency out, EEx ia IIC T4 ( -40°C…+40°C ) or T 4 (-40°C…+70°C )
B Advanced board: 2 x 4-20mA outputs, EEx ia IIC T4 (-40°C…+60°C)
D
E Entrained gas – frequency output (safe area only)
F Entrained gas – Advanced board: 2 x 4-20mA outputs, EEx rating as B.

J ATEX intrinsically safe (see “On-board Electronics” for rating)
L CSA intrinsically safe (Canada and USA)
S Safe area only (entrained gas option).

A API Degrees (Americas) – Advanced board only.
B Base density to API tables (Metric) – Advanced only.
C Line density only – Advanced board only.
D General process incl. matr ix (user d ata) – Ad vanc’d o nly.
T Frequency version – no software to configure.
Z Special

A Instrument standard.
D UKAS calibration (water).
E UKAS calibration (3 liquids).
Z Special

A None.
B Dye penetration (internal welds)
C Dye penetration (all welds)
D Radiography of flange welds + B
E Radiography of flange welds + C
F Radiography of flange welds

A None
X Certificates of material

7845 C B A F B J B A A A

Code Process Connections

Code Material Options

Code Meter Outer Containment

Code Amplifier Enclosure

Advanced board: HART

H

Entrained gas – Advanced board: HART

Code Safety Approval and Label

Code Default Configuration

®

Code Calibration

, 3 x 4-20mA outputs, EEx ia IIB T4 ( -40°C…+60 °C)

®

, 3 x 4-20mA outputs, EEx as C.

Code ASME IX

Code Traceability

(Typical Code)

Page 1-6

7835/45/46/47 Technical Manual Introduction

PART NUMBER IDENTIFICATION FOR 7846

Code Product

7846

HASTELLOY

C 1” ANSI 300 RF
H 25mm DIN 2635 DN25/PN40
J 25mm DIN 2635/2512 GVD DN25/PN40
Z Special

C Alloy C22 wetted parts, 316L Stainless Steel outer case. NACE

A Standard Stainless Steel for tube, mounted ampl ifier or remote amplifier.
B Outer containment (1/4 NPT), stainless ste el for tube , mount ed amp lifiers o r remote amplifie r.
C Secondary containment B31.3 (1/2 NPT) for tube, mounted amplifier or remote amplifier (100Bar)

F Tube mounted flat box in stainless steel.
Code On-board Electronics
A Std frequency out, EEx ia IIC T4 (-4 0°C…+40°C) or T4 (-40 °C…+70°C)
B Advanced board: 2 x 4-20mA outputs, EEx ia IIC T4 (-40°C…+60°C)
D
E Entrained gas – frequency output (safe area only)
F Entrained gas – Advanced board: 2 x 4-20mA outputs, EEx rating as B.
H

J ATEX intrinsically safe (see “On-board Electronics” for rating)
L CSA intrinsically safe (Canada and USA)
S Safe area only (entrained gas option).

A API Degrees (Americas) – Advanced board only.
B Base density to API tables (Metric) – Advanced only.
C Line density only – Advanced board only.
D General process incl. matrix (user data) – Advanc’d only.
T Frequency version – no software to configure.
Z Special

A Instrument standard.
D UKAS calibration (water).
E UKAS calibrati on (3 liquids).
Z Special

A None.
B Dye penetratio n (internal welds)
C Dye penetration (all welds)
D Radiography of flange welds + B
E Radiography of flange welds + C
F Radiography of flange welds

A None
X Certificates of material

7846 C C A F B J B A A A (Typical Code)

Code Process Connect ions

®

C22® Liquid Density Meter

Code Material Options

Code Meter Outer Containment

Code Amplifier Enclosure

®

Advanced board: HART

Entrained gas – Advanced board: HAR T

Code Safety Approval and Label

Code Default Configuration

, 3 x 4-20mA outputs, EEx ia IIB T4 (-40°C… +60°C)

Code Calibration

Code ASME IX

®

, 3 x 4-20mA outputs, EEx as C.

Code Traceability

Page 1-7

Introduction 7835/45/46/47 Technical Manual

PART NUMBER IDENTIFICATION FOR 7847

Code Product

7847 316L STAINLESS STEEL Li qu id Dens ity Meter (HYGIENIC)

C 1” ANSI 300 RF
H 25mm DIN 2635 DN25/PN40
J 25mm DIN 2635/2512 GVD DN25/PN40
P 1” Ladish Tri-Clamp (Hygienic)
S 25mm DIN 11851
Z Special

B Wetted parts 316L Stainless Steel, 316L Stainless Steel outer case.

A Standard Stainless Steel for tube, mounted amplifier or remote amplifier.

F Tube mounted flat box in stainless steel.

A Std frequency out, EEx ia IIC T4 ( -40°C…+40°C ) or T 4 (-40°C…+70°C )
B Advanced board: 2 x 4-20mA outputs, EEx ia IIC T4 (-40°C…+60°C)
D
E Entrained gas – frequency output (safe area only)
F Entrained gas – Advanced board: 2 x 4-20mA outputs, EEx rating as B.
H

J ATEX intrinsically safe (see “On-board Electronics” for rating)
L CSA intrinsically safe (Canada and USA)
S Safe area only (entrained gas option).
T Safe area only (3A’s approved label).

A API Degrees (Americas) – Advanced board only.
B Base density to API tables (Metric) – Advanced only.
C Line density only – Advanced board only.
D General process incl. matr ix (user d ata) – Ad vanc’d o nly.
T Frequency version – no software to configure.
Z Special

A Instrument standard.
D UKAS calibration (water).
E UKAS calibration (3 liquids).
Z Special

A None.
B Dye penetration (internal welds)
C Dye penetration (all welds)
D Radiography of flange welds + B
E Radiography of flange welds + C
F Radiography of flange welds

A None
X Certificates of material

7847 C B A F B J B A A A

Code Process Connections

Code Material Options

Code Meter Outer Containment

Code Amplifier Enclosure

Code On-board Electronics

Advanced board: HART

Entrained gas – Advanced board: HART

Code Safety Approval and Label

Code Default Configuration

Code Calibration

®

, 3 x 4-20mA outputs, EEx ia IIB T4 ( -40°C…+60 °C)

®

, 3 x 4-20mA outputs, EEx as C.

Code ASME IX

Code Traceability

(Typical Code)

Page 1-8

7835/45/46/47 Technical Manual Mechanical Installation

Chapter 2

Mechanical Installation

2.1 General

This chapter describes t he mechanical installation of the Micro Motion® 7835/45/46/47 Liquid Density Meters.

Remember! ALWAYS handle the meters with care

Figure 2.1

When handling…

 Don’t drop the meter or subject it to sever mechanic a l shock.
 Don’t expose the meter to excessive vibration.

When installing…

 Don’t position the rupture disk where failure could cause personal injury.
 Ensure axial loading from pipework does not exceed ½ tonne.
 Ensure electrical safety requirements are met.
 Ensure that the meter and associated pipework are pressure teste d to 1½ time s the maximu m op e rati ng

pressure.

When operating…

 Don’t use liquids incompatible with the construction.
 Don’t operate the meter above its rated pressure.

When transporting…

 Ensure the meter does not contain hazardous fluids, including those that may have leaked into the case.

Page 2-1

Mechanical Installation 7835/45/46/47 Technical Manual

2.2 Planning an installation

When planning the installation of a meter it is important to consider the following factor s:

Safety The meter should be orientated such that, if there is a mechanical structure failure within

Serviceability

Installing the meter in a by-pass configurat ion allows it to be removed for servicing or

Performance

the instrument, the liqui d is discharged from the rupture disc in a safe manner. Please
refer to figure 2.2b for details.

calibration without affecting the main pipeline. Possible by-pass configurations are shown
in Figure 2.2c

Pipe stresses and
vibration

Axial load should not exceed ½ tonne, so pipework should ha ve a degree of flexibility.
Excessive pipe vibration should be av oide d.

Gas bubbles The presence of gas bubbles can seriously affect the meter performance and so the

following points shou ld be considered:-

 The liquid must alw ays be at a pressure substantially above its vapour pressure.
 All pipework couplings and joints must be air tight.
 No vortex should be present at the inlet to the meter.
 Cavitations, caused by pumping, should not gene rat e bub bles from di s sol ved ga ses.
 If a pump is used it is should ‘push’ rather than ‘pull’ the product through the meter.

Note: For entrained gas unit s where the density of aerated m ixtures is to be measured
some of the above recommendations may not be applicable.

Meter orientation

 For low flow rates, e.g. 750 litres/hour (2.7 gal/min.), the meter should preferably be

mounted vertically or at an incline, with the flow in an upwards direction.

 If the liquid contains solid particles, the direction of flow should be upwards unless the

particles are large enough not to be carried with the flow, in which case the direction
of flow should be reversed.

 The meter should be mounted with the electric cable running downwards thereby

minimising the ingress of water should a cable gland become defective.

Flow rate

 A fast flow rate, e.g. 3000 litres /hour (11 gal/min.), will help to achieve good

temperature equilibrium and ha ve a self -cle an i ng action .

 A low flow rate, e.g. 1000 litres/hour (3.7 gal/min.), is recommended if the product

contains particles which may cause erosio n .

 The meters exhibit a small flow dependent density reading. For flow rates up to 15000

litres per hour (55 ga l/min) and assuming no consequent line pressure or product
changes, the maximum density offset will be less than 0.2kg/m

3

.

Temperature
Stability

 The inlet pipework should be thermally lagged to ensure good temperature

stabilisation.

Page 2-2

7835/45/46/47 Technical Manual Mechanical Installation

2.3 Meter Mounting and Pipework

This section considers in more detai l the moun ting of the meters and the design of the associa ted pipe work, includin g the
calculation of pressure drop in the meter.

Installation drawings for all the meter versions are reproduced in the Appendices, along with detailed drawings of the
flanges/couplings. The preferre d meth od s of supp ortin g th e met er are show n in Figure 2.2a.

1st

Meter supported
in two positions around
1” schedule 80 pipe.

Figure 2.2a: Preferred Methods of Mounting Meter

For continuously high flow rates, the mounting position can be selected to simplify the associated pipework and help
minimise the pressure and temperature losses. (See Figure 2.2b below).

2nd

Meter supported
in two positions around
the immediate pipework.

3rd

Meter supported
in two positions around
outer case (4” diameter).

Page 2-3

Mechanical Installation 7835/45/46/47 Technical Manual

1st

Electric Cable

2nd

Electric Cable

FLOW

Direction of flow should
be reversed for slurries.

Rupture plate blow out

Direction of flow should
be reversed for slurrie s .

>60

90

o

o

Rupture plate blow out

FLOW

3rd

Flow rate should be kept high
to prevent gas bubbles & sediment
from forming on the resonant tube.

FLOW

Rupture plate blow out

Figure 2.2b: Meter Preferred Mounting Angle

Page 2-4

Electric Cable

7835/45/46/47 Technical Manual Mechanical Installation

‘S’ Bend Method

Laminar Flow Method

Orifice Plate Method

Pressure Bend Method

Pitot Tube Method

PUMP

Pump Method

PUMP

CLEANING LIQUID

Direction of Flow

Integral Cleaning System

Figure 2.2c: Typica l By-Pass Pipeline Conf ig urations

Page 2-5

Mechanical Installation 7835/45/46/47 Technical Manual







2.4 Pressure Drop in the Meter

The pressure drop in the meter depends on:

 Flow rate (
 Kinematic viscosity (

The table below gives some examples of pressure drop at various flow rates.

Flow Rate Flow Velocity Pressure Drop
(litres/hour)
1000 0.6 0.003 0.004*
4000 2.5 0.033 0.048
12000 7.6 0.238 0.345

* Indicates laminar flow (Fluid Density 1.0g/cc)

Calculation of pressure drop in the meter

The meter should be considered as a straight pipe of 23.6mm (0.929”) internal diameter and 1.03m (40.551”) in length.
The following formula has b een proven to apply to the meter by measurements at 12000 litre s per hour (44 gal/min).

).

V

).

(

V

m/s)

= 2cS =10cS

2

VLf200



h =

Dg



Where:

For viscous or laminar flow (Reynolds N umber

Frictional Coefficient (

For turbulent flow (

R

Frictional Coefficient (

f ) =

greater than 2500)

e

) =

f

and:

h = Pressure drop (bars)

= Friction coefficient

f

L = Pipe length (m) = 1.03
D = Internal pipe diameter (mm) = 23.6

V = Mean fluid velocity (m/s)

 = Fluid density (g/cc)

= 9.81 (m/s2)

g

R less than 2000)

e

16

R

e

064.0

where: Pipe

23.0

R

e

R =

e

DV 1000



= Kinematic viscosity (cS)

In addition to the pressure drop ca used by the liquid flow through the instru ment, it will be necessary to calcu late the
pressure drop in any associated sample pipework before concluding the system design requirements.

Page 2-6

7835/45/46/47 Technical Manual Mechanical Installation

2.5 Special considerations for h ygienic applications

The 7847 meter is specially designed for use in hygienic applications. The following points should be considered when
planning an installation for a hygienic application.

Meter orientation The 7847 should be installed in the vertical plane to prevent the accumulation of product

residue in the convolutions of the bellows, caus ing contamination, especially during the final
rinse when cleaning.

Meter mounting The method of meter mounting should be suitable for the application and cleaning processes

Steam cleaning Where it is necessary to sterilise the meter using the stea m cleaning process, ensure the

Post installation Ensure the cable glands, blanking plugs, lid, and seal are in place and tightened to prevent

used. Process seals appropriate for the media should be used.

temperature and duration of cleaning does not exceed 250 °F (121 °C) for a period of
30 minutes. Exceeding this limit may permanently damage the meter’s amplifier circuit.

moisture and dust ingress.

2.6 Post-Installation Checks

After installation the meter should be pressure tested t o 1.5 times the maximum working pressure of the syst em but NOT
to a value exceeding the meter test figure shown on the meter label.

CAUTION: If the pressure test figure is exceeded, the meter may be irrevocably damaged.

Page 2-7

Mechanical Installation 7835/45/46/47 Technical Manual

Page 2-8

7835/45/46/47 Technical Manual Advanced Unit Electrical Installation and Configuration

Chapter 3

Advanced Unit Electrical Installation and

Configuration

3.1 General

This chapter describes the electrical installation of the 7835 and the 7845, 7846, 7847 Liquid Density Meters when fitted
with the Advanced electronics option.

Option board

Baseboard

Figure 3.1

The first sections of this chapter address the installation and configuration of the Advanced Baseboard, and the later
sections concern the Advanced option boards. Further details about the installation of the Remote Display are given in
Chapter 7.

Remote Display

7965 DISPLAY

Page 3-1

Advanced Unit Electrical Installation and Configuration 7835/45/46/47 Technical Manual

3.2 Planning an Electrical Installation

When planning the electrical installation of an Advanced unit, it is important to consider the points given below.

Safety

• Electrical installation in hazardous areas requires strict

• For installation of the CSA certified unit in a hazardous area, refer to Append i x K.

• For installation of the A TEX certified unit in a hazardous area, refer to the appropriate safety

instructions booklet (78355015/SI, 7835 5038/SI, or 78355065/SI).

adherence to local codes of practice.

Power supply

Ground connections

Cable parameters

• The Advanced electronics operate from a nominal 24V supply, but will operate from any supply
in the range 9.5V to 28V, meas ured at the supply terminals on the baseboard.

• The output circuits on the baseboard are all loop-pow ered and are isolated from the main
circuit. If required, the main circuit and the output circuits can be powered from a common
power supply.

• When selecting a suitable pow er supply voltage, you must take into account voltage drops
caused by the connecting cable (see below) and in hazardous areas, across zener barriers or
galvanic isolators.

• The earthing pads on the baseboard (see Figure 3.3a) must make good contact with the meter
case via the M3 bolts.

®

• If a HART
baseboard earthing points.

• The 0V power supply lead should be earthed at the supply end, or at the safety barriers if

applicable.

• Where long cable lengths are required the cable resistance may be significant. When
operating from a 24V supply in safe areas the following limits apply:

Power supply 260
Remote Display 60
Outputs 500

For further details relating to the maximum line resistance, please refer to Appendix D.

• When calculating the maximum cable lengths please note that the current loop is 2 times the
cable length, and so the cable resistance is given by:

• Typical cables would comply with BS5308 Type 1 or 2.

option board is used, the indicated earthing point must make good contact with the

Maximum line resistance (Ω)

2 x (dc resistance per unit length) x (cab le length)

EMC

Page 3-2

• To meet the EC Directive for EMC (Electromagnetic Compatibility), it is recommended that the
meter be connected using a suitable instrumentation cable.

The instrumentation cable should have individual screen(s), foil or braid over each twisted pair
and an overall screen to cover all cores. Where permissible, the overall screen should be
connected to earth at both ends (360° bonded at both ends). The inner individual screen(s)
should be connected at only one end, the controller (e.g. signal conver ter) end.

• Note that for intrinsic safety, termination of the inne r individual screen(s) to earth in the
hazardous area is NOT generally permitted.

• Metal cable glands should be used where the cables enter the meter amplifier box. Unused
cable ports should be fitted with metal blank ing plugs.

• When the 78452 (Advanced Remote Amplifier) is used, the ferrite ring, which is supplied, must
be fitted around the connecting cab le. For ins t all ation in hazardous areas, refer to the certified
system drawings in Appendix K, and the safety inst ruc ti on bo okl et (7 83 550 1 5/ SI or
78355038/SI) that came with the meter.

7835/45/46/47 Technical Manual Advanced Unit Electrical Installation and Configuration

3.3 Electrical installation in safe areas

All connections to the baseboard are made to terminals 1 to 12 of the terminal block PL2 as shown in Figure 3.2.

Earthing Point

1

234 5

6

7

89

10

11

12

+

PULSE 1

-

+

ANALOG 1

-

+

ANALOG 2

-

SUPPLY +

0V

-

+

DISPLAY

A
B

OPTIONAL

BOARD

Analog 1

22mA

2mA

Alarm

Analog 2

22mA

2mA

Alarm

P/U1
P/U2

PRT -

SIG -

SIG +

PRT +

DRIVE

PL1

1

234

0V

5

6

78

9

PL2

Earthing Point

Jumper Links

Foam support strip

Figure 3.2: Baseboard Layout

Note: There is no reason to remove the baseboard under normal circumstances. If it is removed, however, care should

be taken, when replacing the board, to push it firmly against the foam strip, as this helps to prevent the board from
excessive flexing.

Page 3-3

Advanced Unit Electrical Installation and Configuration 7835/45/46/47 Technical Manual

Figure 3.3 shows a schematic representation of the electrical connection diagram for the Advanced Baseboard and Remote
Display in safe areas. In this example, the pulse output is shown driving an alarm device such as a relay.

+5V to 28V

Pulse

Output

Analog
Output

Analog
Output

(as above)

500Ω MAX

+16V to 28V

0V

500Ω minimum

1000Ω typical

0V

9.5V to 28V dc
Power Supply

_

+

Load

Advanced

Density

Baseboard

1 +

Pulse

}

2 -

PL2 Connections

3 +

Analog 1

}

4 -

5 +

Analog 2

}

6 -

7 +

Supply

}

Cable Screen 1

Remote
Display

Page 3-4

0V Power 2

+ve Power 3

A 4

B 5

Figure 3.3: Connection Diagram (Safe areas)

8 -

9 -

10 +

11 A

12 B

}

Remote

Display

7835/45/46/47 Technical Manual Advanced Unit Electrical Installation and Configuration

3.3.1 Electrical Installation with Signal Converter / Flow Computer

Figure 3.4 shows a typical electrical connection diagram for use in safe areas using flow computers and signal converters.

7835/45/46/47 with

Advanced Electronics

Freq/Alarm

+VE

1

-VE

2

Analog 1 (Analog 2)

(5)

+VE

3

(6)

4

-VE

Power Supply

7

+VE

8

-VE

1000Ω

7950/51/55
7915/25/26/45/46

+ Density Pwr

+ Density Input

- Density Pwr

- Density Input

+ Density Pwr

+ Analog Input

- Density Pwr

- Analog Input

+Density Pwr

- Density Pwr

SEE FLOW

COMPUTER/

SIGNAL

CONVERTER

HANDBOOK

FOR

CONNECTION

DETAILS

Figure 3.4: Electrical connection diagram when using a flow computer / signal converter (Safe area)

Page 3-5

Advanced Unit Electrical Installation and Configuration 7835/45/46/47 Technical Manual

Ω

Ω

3.4 Electrical installation in hazardous areas

When used in hazardous areas, safety barriers MUST be interposed between the meter and the signal processing
equipment. Some of the safety barriers are unsuitable for certain installations, as discussed below.

Note:

• For installation of the CSA certified unit in a hazardous area, refer to Appendix K.

• For installation of the ATEX certified unit in a hazardous area, refer to the appropriate safety

instructions booklet (78355015/SI, 78355038/SI, or 78355065/SI).

3.4.1 Safety Barrier and Galvanic Isolator Selection

3.4.1.1. Power Supply (PL2 terminals 7 and 8)

As a general rule, the IIB safety barrier should be used where possible as this allows the maximum power to the meter,
facilitating a wide range of installations and system configurations.

Where the installation requires the IIC safety barrier, it is important to check that sufficient power is available to power
the meter and all of the options. The table below summarises the maximum line resistances allowable for the main
system configurations assuming a 24V supply and a minimum of 9.5V available at the supply terminals on the baseboard.

Table 3.1

Advanced System combination

Baseboard 340

Baseboard + remote display 260

Baseboard + locally powered remote display 280

Baseboard + HART® board 270

Baseboard + HART® + display 250

Zener Safety Barriers

Power to the main circuit may be obtained through a simple 164Ω barrier or two 300Ω 28V barriers in parallel for IIB
applications, or through a single 234Ω 28V barrier in IIC applications.

The main characteristics of the safety barriers are given here. Using this information and the information given in the
table above the most suitable barriers for a particular application can be ascertained.

Table 3.2

Type Group

MTL 729P IIB 164 184

MTL 728P IIC 234 253

P&F Z728H IIC 240 250

Note: The power supply input is protected internally by an 8.2V±5% clamp diode and a 1Ω resistor. This limits the
maximum current that can flow into the device:

I

max

Maximum voltage from barrier

=

Safety Description (

Minimum resistance of barrier/input combination

Maximum line resistance (

) Max. resistance (Ω)

- Minimum voltage at input

) (barrier + cable)

For example, if two 28V, 300Ω barriers are used in parallel, the effective resistance is 150Ω.
The maximum current is:

()

95.02.828

I

=

max

…and not 185mA, as might be expected if the input protection diode was not present.

Page 3-6

×−

= 134mA

1150

+

7835/45/46/47 Technical Manual Advanced Unit Electrical Installation and Configuration

Ω

Galvanic Isolators

Galvanic isolators are suitable for powering the main board in IIB applications, but are NOT suitable for powering the main
board in

IIC applications. Also, IIC isolators are not suitable for use when Modbus communications are required.

The main characteristics of the galvanic isolators are given here. Using this information and the information given in the
table above, the most suitable galvanic isolators for a particular application can be ascertained.

Table 3.3

Type Group

Max output impedance (

)

MTL 3022 IIB 165

P&F KFD2-SD-Ex1.36 IIB 160

P&F KFD2-SL-Ex1.36 IIB 160

MTL 5022 IIB 143

3.4.1.2. Analogue (4 to 20mA) outputs including HART

®

(PL2 terminals 3 & 4, 5 & 6 and HART PL3 3 & 4)

Any of the zener safety barriers listed on the system certificates are suitable for operation with the Advanced Density
analogue outputs. Some galvanic isolators may not be capable of driving the 2mA and 22mA out-of-range alarm states
available on the Advanced Density system; for details please check with the barrier supplier.

3.4.1.3. Pulse output

(PL2 terminals 1 & 2)

The pulse output can be configured to output either a status / alarm signal or the resonant frequency of the density meter;
the latter requires the safety barrier to have a bandwidth of at least 1 kHz.

The table below indicates which galvanic isolators may be used for frequency configured pulse output; zener barriers may
be used for either configuration.

Table 3.4

Isolator type Output description Pulse output configuration

MTL3011 Relay Status / alarm

MTL3012 Solid state (dc to 2kHz) All

MTL4013 Solid state (dc to 5kHz) All

MTL4014 Relay Status / alarm

MTL5011 Relay Status / alarm

MTL5016 Relay Status / alarm

MTL5017 Relay Status / alarm

Page 3-7

Advanced Unit Electrical Installation and Configuration 7835/45/46/47 Technical Manual

3.5 Baseboard Configuration

The baseboard is supplied with one of the following two software versions:

•

General software version - normally used in the food and process industries.

•

Fiscal software version - normally used in Crude oil or refined petroleum applications.

The only difference between the two software versions is the available calculations.

Irrespective of which software version is running, when the unit is received from the factory, it is pre-configured to output
the following signals:

Table 3.5

Output Output Parameter

Analog 1 (4-20mA) = Line density (500 to 1500 kg/m³)

Analog 2 (4-20mA) =

Pulse output = Alarm - normally on

For many applications, the factory default configuration described above will be quite acceptable. However, if any of the
additional calculated parameters or different output ranges are required, then a simple Baseboard re-configuration can be
performed using a Remote Display, or PC.

For details on the available calculations and other Baseboard configuration factors, please refer to Appendix E.

Temperature (0 to 100

°C)

Page 3-8