Micro Motion Compact Density Meter 100 Retrofit Manuals & Guides

Installation Manual

MMI-20020999, Rev AC

May 2018

Micro Motion® Compact Density Meter (CDM)

7835/7845 Liquid Density Meter Retrofit Installation

Safety and approval information

This Micro Motion product complies with all applicable European directives when properly installed in accordance with the
instructions in this manual. Refer to the EU declaration of conformity for directives that apply to this product. The EU declaration of
conformity, with all applicable European directives, and the complete ATEX Installation Drawings and Instructions are available on
the internet at www.emerson.com or through your local Micro Motion support center.

Information affixed to equipment that complies with the Pressure Equipment Directive, can be found on the internet at

www.emerson.com.

For hazardous installations in Europe, refer to standard EN 60079-14 if national standards do not apply.

Other information

Full product specifications can be found in the product data sheet. Troubleshooting information can be found in the configuration
manual. Product data sheets and manuals are available from the Micro Motion web site at www.emerson.com.

Return policy

Follow Micro Motion procedures when returning equipment. These procedures ensure legal compliance with government
transportation agencies and help provide a safe working environment for Micro Motion employees. Micro Motion will not accept
your returned equipment if you fail to follow Micro Motion procedures.

Return procedures and forms are available on our web support site at www.emerson.com, or by phoning the Micro Motion Customer
Service department.

Emerson Flow customer service

Email:

• Worldwide: [e-mail]

• Asia-Pacific: [e-mail]

Telephone:

North and South America Europe and Middle East Asia Pacific

United States 800-522-6277 U.K. 0870 240 1978 Australia 800 158 727

Canada [phone] The Netherlands [phone] New Zealand 099 128 804

Mexico [phone] France 0800 917 901 India 800 440 1468

Argentina [phone] Germany 0800 182 5347 Pakistan 888 550 2682

Brazil [phone] Italy 8008 77334 China [phone]

Central & Eastern [phone] Japan [phone]

Russia/CIS [phone] South Korea [phone]

Egypt 0800 000 0015 Singapore [phone]

Oman 800 70101 Thailand 001 800 441 6426

Qatar 431 0044 Malaysia 800 814 008

Kuwait 663 299 01

South Africa 800 991 390

Saudi Arabia 800 844 9564

UAE 800 0444 0684

Contents

Contents

Chapter 1 Planning ...........................................................................................................................1

1.1 Retrofit installation overview ..........................................................................................................1

1.2 Installation checklist .......................................................................................................................1

1.3 Best practices .................................................................................................................................2

1.4 Pressure drop in the meter ............................................................................................................. 3

1.5 Power requirements .......................................................................................................................5

1.6 Spacing requirements .................................................................................................................... 9

1.7 Perform a pre-installation meter check .........................................................................................11

Chapter 2 Removing a 7835/7845 meter ........................................................................................ 12

2.1 Disconnect the 7835/7845 meter wiring ......................................................................................12

2.2 Remove the meter from the pipeline ............................................................................................14

Chapter 3 Mounting .......................................................................................................................15

3.1 Mount the meter ..........................................................................................................................15

3.2 Rotate the electronics on the meter (optional) .............................................................................16

3.3 Rotate the display on the transmitter (optional) ...........................................................................17

Chapter 4 Wiring ........................................................................................................................... 19

4.1 Wiring to external devices (HART multidrop) ................................................................................19

4.2 Terminals and wiring requirements .............................................................................................. 19

4.3 Retrofit wiring: terminal-to-output conversions ........................................................................... 20

4.4 Explosion-proof/flameproof or non-hazardous output wiring .......................................................22

4.5 Intrinsically safe output wiring ......................................................................................................26

4.6 Processor wiring for remote-mount 2700 FOUNDATION™ fieldbus option ....................................34

4.7 Wiring to signal converters and/or flow computers ...................................................................... 39

Chapter 5 Grounding ......................................................................................................................42

Installation Manual i

Contents

ii Micro Motion Compact Density Meter 7835/7845 Retrofit

1 Planning

Topics covered in this chapter:

Retrofit installation overview

•

Installation checklist

•

Best practices

•

Pressure drop in the meter

•

Power requirements

•

Spacing requirements

•

Perform a pre-installation meter check

•

1.1 Retrofit installation overview

Following is an overview of the tasks required to install the Compact Density Meter (CDM)
as a replacement to the Micro Motion 7835/7845 liquid density meter. We recommend
that you review this information before beginning the retrofit installation.

Planning

Process

Confirm you have all parts necessary and meet the basic installa­tion requirements.

Consider the installation best practices for the removal and in­stallation of your meter(s).

Confirm any additional wiring, external power supplies, and/or
resistance needed to wire to the CDM.

Remove the existing 7835/7845 liquid density meter. See Chapter 2

Mount the CDM retrofit meter. See Chapter 3

Wire the meter according to the recommended practices for
your process environment and required approvals.

Ground the meter. See Grounding

1.2 Installation checklist

□

Make sure that the hazardous area specified on the approval tag is suitable for the
environment in which the meter will be installed.

□

Verify that the local ambient and process temperatures are within the limits of the
meter.

□

Verify the spacing requirements for the retrofit meter installation (see Section 1.6).

Reference

See Section 1.2

See Section 1.3

See Chapter 4

See Chapter 4

Installation Manual 1

Planning

□

Verify the retrofit wiring requirements, which may vary depending on your existing
transmitter configuration:

- Confirm the CDM input/output wiring requirements (see Chapter 4).

Tip

Depending on your current configuration, you may need additional wiring or can reuse
wiring that had been connected to devices no longer needed.

- For intrinsically safe hazardous area installations, you must purchase new barriers

or isolators. You cannot reuse existing safety barriers or galvanic isolators for
connecting to the CDM.

Tip

Micro Motion provides safety barrier and galvanic isolator installation kits for wiring the
CDM in a hazardous environment. These kits provide the appropriate barriers or isolators
depending on the outputs available and approvals required. Contact

[e-mail] for more information on ordering these kits.

□

If your meter will be wired to a remote-mount 2700 FOUNDATION™ fieldbus
transmitter:

- Refer to the instructions in this manual for preparing the 4-wire cable and wiring

to the processor connections. See Section 4.6.

- Refer to the instructions in the transmitter installation manual for mounting and

wiring the 2700 FOUNDATION™ fieldbus transmitter.

- Consider the maximum cable length between the meter and transmitter. The

maximum recommended distance between the two devices is 1000 ft (300 m).
Micro Motion recommends using Micro Motion cable.

□

Install the meter so that the flow direction arrow on the meter case matches the
actual forward flow of the process. (Flow direction is also software-selectable.)

□

For optimal performance, thermally insulate the meter and the inlet and bypass­loop pipeline to maintain stable temperatures.

Tip

Micro Motion offers a soft, weather-proof insulating jacket that is easily fitted to all CDM
versions.

1.3

2 Micro Motion Compact Density Meter 7835/7845 Retrofit

Best practices

The following information can help you get the most from your meter.

• Handle the meter with care. Follow local practices for lifting or moving the meter.

• Perform a Known Density Verification (KDV) check of the meter prior to installing

the meter in your system.

• Install the meter in the preferred orientation in a vertical pipeline with liquids and

slurries flowing upward.

Planning

Important

If you do not install the meter in the preferred orientation, you may need to apply a field
offset to ensure optimal performance. Refer to your organizational standards for sampling
and reference measurement to determine what the offset may be.

• If you are installing the meter into an application configuration requiring differential

pressure, confirm the current configuration is suitable for the CDM.

• Do not apply a compression force greater than 200 lbs (90.7 kg) when installing the

meter.

• Thermally insulate the meter and the inlet and bypass-loop pipeline to maintain

stable temperatures.

• There are no pipe run requirements for Micro Motion meters. Straight runs of pipe

upstream or downstream are unnecessary.

• Keep the meter tubes full of process fluid.

• For halting flow through the meter with a single valve, install the valve downstream

from the meter.

• Minimize bending and torsional stress on the meter. Do not use the meter to align

misaligned piping.

• The meter does not require external supports. The flanges will support the meter in

any orientation.

• For bypass configurations using a pump, install the pump downstream of the meter

to avoid pump heat transfer.

• For bypass configurations, maintain a target flow through the meter to ensure

sample integrity and consistent temperature with the main line.

1.4

Installation Manual 3

Pressure drop in the meter

The pressure drop in the meter depends on the process conditions. The following figures
illustrate the pressure drop for the meter at varying fluid density and viscosity. In addition,
these charts show how the meter compares to the Micro Motion 7835/7845 liquid density
meters.

Important

For the most accurate pressure drop calculations using your process variables, use the Micro Motion
product selector available at www.emerson.com.

Planning

Sample pressure drop calculations (fluid viscosity equals 2 cP)Figure 1-1:

A. Pressure drop (bar)
B. Flow rate (m3/hr)

Note

• Density = 800 kg/m

• Viscosity = 2 cP

3

4 Micro Motion Compact Density Meter 7835/7845 Retrofit

Planning

Sample pressure drop calculations (fluid viscosity equals 10 cP)Figure 1-2:

1.5

A. Pressure drop (bar)
B. Flow rate (m3/hr)

Note

• Density = 800 kg/m

• Viscosity = 10 cP

3

Power requirements

Following are the DC power requirements to operate the meter:

• Explosion-proof/flameproof meters:

- 24 VDC, 0.65 W typical, 1.1 W maximum

- Minimum recommended voltage: 21.6 VDC with 1000 ft of 24 AWG (300 m of

0.20 mm2) power-supply cable

- At startup, power source must provide a minimum of 0.5 A of short-term current

at a minimum of 19.6 V at the power-input terminals.

• Intrinsically safe meters:

- 24 VDC, 0.7 W typical with 250 Ω barrier, 0.96 W maximum with 250 Ω barrier

- Minimum recommended voltage: 22.8 VDC with 1000 ft of 22 AWG (300 m of

0.25 mm2) power-supply cable

Installation Manual 5

300ft 600ft 900ft 1200ft 1500ft 1800ft 2100ft 2400ft 2700ft 3000ft

B

2 1 . 6V
24 V

14

15

16

17

18

19

20

21

22

23

24

25

26

A

91.44m 182.88m 274.32m 365.76m 457.2m 548.64m 640.08m 731.52m 822.96m 914.4m

Planning

Power cable recommendations for explosion-proof/flameproof meters

Minimum wire gauge (AWG per feet )Figure 1-3:

A. AWG maximum
B. Distance of installation

6 Micro Motion Compact Density Meter 7835/7845 Retrofit

0

. 00 0

0.100

0.200

0.300

0.400

0.500

0.600

0.700

10 0m 20 0m 30 0m 40 0m 50 0m 60 0m 70 0m 80 0m 90 0m 100 0m

B

2 1 . 6V
24 V

A

328.084 ft 656.168ft 984.253ft 1312.34ft 1640.42ft 1968.5ft 2296.59ft 2624.67ft 2952.76ft 3280.84ft

Planning

Minimum wire area (mm2 per meter)Figure 1-4:

A. Minimum wire area (mm2)
B. Distance of installation

Installation Manual 7

3 0 0 6 0 0 9 0 0 12 0 0 1 50 0 18 0 0 21 0 0 24 0 0 27 0 0 3 00 0

22 . 8 V
24 V

14

15

16

17

18

19

20

21

2 2

23

24

25

26

A

B

Planning

Power cable recommendations for intrinsically safe meters

Minimum wire gauge (AWG per feet)Figure 1-5:

A. AWG
B. Distance of installation

8 Micro Motion Compact Density Meter 7835/7845 Retrofit

Planning

Minimum wire area (mm2 per meter)Figure 1-6:

1.6

A. Minimum wire area (mm2)
B. Distance of installation

Spacing requirements

When determining spacing requirements, be sure to consider the height requirements of
the CDM in relation to the existing 7835/7845 meter (see Figure 1-8).

Installation Manual 9

12.6

(320)

Dimensions in

inches
(mm)

Explosion Proof 7835

Intrinsically Safe 7835/7845

6.2

(158.6)

Planning

CDM retrofit meter dimensionsFigure 1-7:

A. Dim. A — face to face is up to 40.4 inches (1026 mm) ± 0.125 in (3 mm)
B. Nominal flow direction — the meter can be configured for normal (forward), reversed, or bi-

directional flow

C. 2x 1/2-14 NPT female electronic interface

Note

Drawing dimensions are in inches.

7835/7845 meter dimensions (height only)Figure 1-8:

10 Micro Motion Compact Density Meter 7835/7845 Retrofit

1.7 Perform a pre-installation meter check

MTL7728P+

3

4

1

2

A

Check the meter prior to installation to confirm that no damage occurred to the meter
during shipment.

Procedure

1. Remove the meter from the box.

CAUTION!

Handle the meter with care. Follow all corporate, local, and national safety regulations
for lifting and moving the meter.

2. Visually inspect the meter for any physical damage.

If you notice any physical damage to the meter, immediately contact Micro Motion
Customer Support at [e-mail].

3. Position and secure the meter in a vertical position with the flow arrow pointing
upward.

4. Connect the power wiring, and power up the meter.

Planning

Remove the back transmitter housing cover to access the PWR terminals.

Power supply wiring terminalsFigure 1-9:

A. Barrier wiring is applicable to intrinsically safe installations only

5. Perform a Known Density Verification (KDV) check.

Use the Known Density Verification procedure to match the current meter
calibration with the factory calibration. If the meter passes the test, then it has not
drifted or changed during shipment.

For more information on performing a KDV check, see the configuration and use
manual that shipped with the product.

Installation Manual 11

Removing a 7835/7845 meter

2 Removing a 7835/7845 meter

Topics covered in this chapter:

Disconnect the 7835/7845 meter wiring

•

Remove the meter from the pipeline

•

2.1 Disconnect the 7835/7845 meter wiring

Prerequisites

• Be prepared to manually record the existing wiring connections to the 7835/7845

meter. You will use this information in re-wiring to the CDM.

• If you are using the 7835/7845 with Advanced electronics, be sure to record the

parameters and ranges for the analog (mA) outputs — for example, Analog 1 is line
density; 4-20 mA is 700-1000 kg/m3.

CAUTION!

Confirm the applicable codes of practice for disconnecting and removing a meter. Meter
installation and/or removal should be performed by suitably trained personnel only.

Procedure

1. Power down the 7835/7845 meter.

2. If the meter is in a hazardous area, wait five minutes before proceeding to the next
step.

3. Remove the thermal insulation from the meter and the surrounding pipework (if
applicable).

4. Remove the electronics housing cover to reveal the 7835/7845 wiring connections.

5. Manually record the existing wiring connections to the 7835/7845 meter.

If you reuse the existing wiring, you should be sure to identify which wires
connected to specific outputs and/or input devices in your existing configuration.
You will use this information to match the wire connections to the appropriate
input/output on the CDM.

The following figures identify the terminal locations for the Standard electronics
board (see Figure 2-1) and Advanced electronics board (see Figure 2-2).

12 Micro Motion Compact Density Meter 7835/7845 Retrofit

Removing a 7835/7845 meter

Standard electronics terminal locationsFigure 2-1:

Advanced electronics terminal locationsFigure 2-2:

6. Disconnect wiring from the meter.

Installation Manual 13

Removing a 7835/7845 meter

2.2 Remove the meter from the pipeline

Prerequisites

Before you loosen or remove any connection, depressurize and drain the meter in
accordance with the applicable codes of practice.

CAUTION!

You must take suitable precautions to ensure your safety if the equipment has come into
contact with aggressive substances. Meter removal should be performed by suitably trained
personnel only in accordance with applicable codes of practice.

Procedure

1. Disconnect the meter (break the seal).

2. Remove the meter.

CAUTION!

Handle the meter with care when lifting and removing it from the pipeline.
Micro Motion recommends that you use lifting straps fitted to the flanged ends to
account for the meter weight and its sensitivity to impact.

3. Dispose of the meter in accordance with your local practices (if applicable).

14 Micro Motion Compact Density Meter 7835/7845 Retrofit

3 Mounting

Topics covered in this chapter:

Mount the meter

•

Rotate the electronics on the meter (optional)

•

Rotate the display on the transmitter (optional)

•

3.1 Mount the meter

Use your common practices to minimize torque and bending load on process connections.

Tip

To reduce the risk of condensation or excessive moisture, the transmitter conduit opening should
not point upward (if possible). The conduit opening of the transmitter can be rotated freely to
facilitate wiring.

Mounting

CAUTION!

Do not lift the meter by the electronics. Lifting the meter by the electronics can damage the
device.

Installation Manual 15

Mounting

Mounting the sensorFigure 3-1:

3.2

Notes

• Do not use the meter to support the piping.

• The meter does not require external supports. The flanges will support the meter in any orientation.

• All pipework joints and couplings must be airtight to minimize the presence of gas bubbles in the

fluid.

Rotate the electronics on the meter (optional)

You can rotate the transmitter on the meter up to 90°.

1. Using a 4 mm hex key, loosen the cap screw that holds the transmitter in place.

16 Micro Motion Compact Density Meter 7835/7845 Retrofit

Component to secure transmitter in placeFigure 3-2:

A

A. M5 socket-head cap screw

2. Rotate the transmitter clockwise to the desired orientation up to 90°.

3. Secure the cap screw in place and tighten to 60 lb·in (6.8 N·m).

Mounting

3.3 Rotate the display on the transmitter (optional)

The display on the transmitter electronics module can be rotated 90° or 180° from the
original position.

Installation Manual 17

B

C

D

A

D

E

Mounting

Display componentsFigure 3-3:

A. Transmitter housing
B. Sub-bezel
C. Display module
D. Display screws
E. Display cover

Procedure

1. If the meter is powered up, power it down.

2. Turn the display cover counterclockwise to remove it from the main enclosure.

3. Carefully loosen (and remove if necessary) the semi-captive display screws while

holding the display module in place.

4. Carefully pull the display module out of the main enclosure until the sub-bezel pin

terminals are disengaged from the display module.

Note

If the display pins come out of the board stack with the display module, remove the pins and
reinstall them.

5. Rotate the display module to the desired position.

6. Insert the sub-bezel pin terminals into the display module pin holes to secure the

display in its new position.

7. If you have removed the display screws, line them up with the matching holes on the

sub-bezel, then reinsert and tighten them.

8. Place the display cover onto the main enclosure.

9. Turn the display cover clockwise until it is snug.

10. If appropriate, power up the meter.

18 Micro Motion Compact Density Meter 7835/7845 Retrofit

4 Wiring

Topics covered in this chapter:

Wiring to external devices (HART multidrop)

•

Terminals and wiring requirements

•

Retrofit wiring: terminal-to-output conversions

•

Explosion-proof/flameproof or non-hazardous output wiring

•

Intrinsically safe output wiring

•

Processor wiring for remote-mount 2700 FOUNDATION™ fieldbus option

•

Wiring to signal converters and/or flow computers

•

4.1 Wiring to external devices (HART multidrop)

You can wire up to three external HART devices with the meter. The following information
provides wiring diagrams for making those connections in safe and hazardous
environments.

Wiring

4.2 Terminals and wiring requirements

Three pairs of wiring terminals are available for transmitter outputs. These outputs vary
depending on your transmitter output option ordered. The Analog (mA), Time Period
Signal (TPS), and Discrete (DO) outputs require external power, and must be connected to
an independent 24 VDC power supply.

For meters connecting to a remote-mount Model 2700 FOUNDATION™ fieldbus
transmitter, you must wire the meter to the remote-mount Model 2700 transmitter using
a 4-wire cable connection. See the processor wiring content in this manual for information
on how to wire the meter.

The screw connectors for each output terminal accept a maximum wire size of 14 AWG
(2.5 mm2).

Important

• Output wiring requirements depend on whether the meter will be installed in a safe area or a

hazardous area. It is your responsibility to verify that this installation meets all corporate,
local, and national safety requirements and electrical codes.

• If you will configure the meter to poll an external temperature or pressure device, you must

wire the mA output to support HART communications. You may use either HART/mA single­loop wiring or HART multi-drop wiring.

Installation Manual 19

Wiring

Transmitter outputsTable 4-1:

Output channels

Transmitter version

Analog 4–20 mA + HART 4–20 mA Modbus/RS-485

Time period signal (TPS) 4–20 mA + HART Time Period Sig-

Discrete 4–20 mA + HART Discrete output Modbus/RS-485

Processor for remote-mount Model
2700 FOUNDATION fieldbus

A B C

nal (TPS)

Disabled Disabled Modbus/RS-485

4.3 Retrofit wiring: terminal-to-output conversions

Depending on your current wiring configuration: additional wiring, power supplies, and/or
resistance may be required to connect to the CDM. The following information explains the
available outputs and wiring requirements of the CDM, and the pin-to-output connector
relationships from the 7835/7845 to CDM.

4.3.1

Rewire from 7835/7845 Standard electronics meter

To wire from an existing 7835/7845 meter with Standard electronics, you must have
purchased the CDM with the Time Period Signal (TPS) output. The rewiring from a
Standards electronics installation requires reconnecting wiring from the 7835/7845 meter
and a signal converter/flow computer device.

Modbus/RS-485

Procedure

See the following for information on the terminal-to-output relationships from the
7835/7845 and signal converter/flow computer to the CDM.

Important

Depending on whether you are wiring in an explosion proof/flameproof or intrinsically safe area, see
the additional information documented for these types of installations.

Take the wire from terminal

Function

Time period Pin 1 (on 7835/7845 meter) TPS +

20 Micro Motion Compact Density Meter 7835/7845 Retrofit

pin:

Pin 2 (on 7835/7845 meter) TPS –

...and, connect it to the CDM output ter­minal:

Wiring

Take the wire from terminal

Function

Temperature Signal converter/flow comput-

Power supply Signal converter/flow comput-

pin:

er terminals for temperature

(See the signal converter/flow
computer manual for more in­formation on the device termi­nals.)

er terminals for power

(See the signal converter/flow
computer manual for more in­formation on the device termi­nals.)

...and, connect it to the CDM output ter­minal:

Two wires from the signal converter/flow
computer connect to:

• mA 1 +

• mA 1 –

Important

You must configure the mA output 1 to
Temperature to provide this measure­ment.

Two wires from the signal converter/flow
computer connect to:

• PWR +

• PWR –

4.3.2 Rewire from 7835/7845 Advanced electronics meter

To wire from an existing 7835/7845 meter with Advanced electronics, you must have
purchased one of the following CDM transmitter versions:

• Analog

• Time Period Signal (TPS)

• Any option with Modbus/RS-485

• Processor for remote-mount 2700 FOUNDATION™ fieldbus

Procedure

See the following for information on the terminal-to-output relationships from the
7835/7845 to the CDM.

Important

Depending on whether you are wiring in an explosion proof/flameproof or intrinsically safe area, see
the additional information documented for these types of installations.

Take the wire from terminal

Function

Time period or sta­tus output

Analog 1 Pin 3 mA 1 +

(1)

pin:

Pin 1 TPS +

Pin 2 TPS –

Pin 4 mA 1 –

...and, connect it to the CDM output ter­minal:

Installation Manual 21

Wiring

Take the wire from terminal

Function

Analog 2 Pin 5 mA 2 +

Power supply Pin 7 PWR +

Remote display Pin 9 If you purchased a CDM with an integral

RS-485 Pin 11 RS-485 A

If using the optional HART/mA output board:

HART HART/mA output board con-

Analog 3 If using a third mA output, no third mA

(1) For further information regarding the status output, refer to the 7835/7845 Installation & Configuration

manual.

pin:

Pin 6 mA 2 –

Pin 8 PWR –

Pin 10

Pin 12 RS-485 B

nections

...and, connect it to the CDM output ter­minal:

transmitter and display, the Remote Dis­play wiring is no longer needed.

If used for HART, this is now available on
mA output 1 (wire accordingly)

output option is available on the CDM. You
must wire to an external HART device.

4.4

Explosion-proof/flameproof or non-hazardous output wiring

4.4.1 Wire the Analog outputs version in an explosion-proof/ flameproof or non-hazardous area

CAUTION!

Meter installation and wiring should be performed by suitably trained personnel only in
accordance with the applicable code of practice.

Procedure

Wire to the appropriate output terminal and pins (see Figure 4-1).

22 Micro Motion Compact Density Meter 7835/7845 Retrofit

mA1+
HART

RS-485

PWR

mA2

AA

B

RS-485 A

RS-485 B

C

D

B

B

A

A

A

Wiring

Wiring the Analog outputsFigure 4-1:

A. 24 VDC
B. R

(250 Ω resistance)

load

C. HART-compatible host or controller; and/or signal device
D. Signal device

Note

For operating the milliamp outputs with a 24V supply, a maximum total loop resistance of 657 Ω is
allowed.

CAUTION!

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable

instrumentation cable to connect the meter. The instrumentation cable should have individual
screens, foil or braid over each twisted pair, and an overall screen to cover all cores. Where
permissible, connect the overall screen to earth at both ends (360° bonded at both ends).
Connect the inner individual screens at only the controller end.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable ports

with metal blanking plugs.

Installation Manual 23

Wiring

4.4.2 Wire the Time Period Signal (TPS) or Discrete output
version in an explosion-proof/flameproof or non­hazardous area

CAUTION!

Meter installation and wiring should be performed by suitably trained personnel only in
accordance with the applicable code of practice.

Procedure

Wire to the appropriate output terminal and pins (see Figure 4-2).

24 Micro Motion Compact Density Meter 7835/7845 Retrofit

mA1+
HART

RS-485

PWR

TPS/DO

AA
B

RS-485 A

RS-485 B

C

E

D

B

A

A

A

Wiring

Wiring the TPS or Discrete output versionFigure 4-2:

A. 24 VDC
B. R

(250 Ω resistance)

load

C. HART-compatible host or controller; and/or signal device
D. R

(500 Ω resistance recommended)

load

E. Signal converter/flow computer or discrete input device

Note

• For operating the milliamp output with a 24V supply, a maximum total loop resistance of 657 Ω is

allowed.

• When operating the TPS or Discrete output with a 24 VDC power supply, a maximum total loop

resistance of 1300 Ω is allowed.

CAUTION!

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable

instrumentation cable to connect the meter. The instrumentation cable should have individual
screens, foil or braid over each twisted pair, and an overall screen to cover all cores. Where
permissible, connect the overall screen to earth at both ends (360° bonded at both ends).
Connect the inner individual screens at only the controller end.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable ports

with metal blanking plugs.

Installation Manual 25

Wiring

4.5 Intrinsically safe output wiring

Micro Motion provides safety barrier and galvanic isolator installation kits for wiring the
meter in a hazardous environment. These kits provide the appropriate barriers or isolators
depending on the outputs available and approvals required.

Information provided about wiring the safety barriers and galvanic isolators is intended as
an overview. You should wire the meter according to the standards that are applicable at
your site.

CAUTION!

• Meter installation and wiring should be performed by suitably trained personnel only in

accordance with the applicable code of practice.

• Refer to the hazardous area approvals documentation shipped with your meter. Safety

instructions are available on the Product Documentation DVD and accessible at

www.emerson.com.

4.5.1 Hazardous area entity parameters

DANGER!

• Hazardous voltage can cause severe injury or death. To reduce the risk of hazardous

voltage, shut off power before wiring the meter.

• Improper wiring in a hazardous environment can cause an explosion. Install the meter

only in an area that complies with the hazardous classification tag on the meter.

Input entity parameters

Input entity parameters: all connectionsTable 4-2:

4–20 mA /Discrete
Output/Time Period

Parameter Power supply

Voltage (Ui) 30 VDC 30 VDC 18 VDC

Current (Ii) 484 mA 484 mA 484 mA

Power (Pi) 2.05 W 2.05 W 2.05 W

Internal capacitance
(Ci)

Internal inductance (Li) 0.0 H 0.0 H 0.0 H

0.0 pF 0.0 pF 0.0011 pF

Signal RS-485

RS-485 output and cable parameters

All connections to the meter receive their power from the connected intrinsically safe
barrier. All cable parameters are derived from the output parameters of these devices. The
RS-485 connection also receives power from the connected barrier (MTL7761AC),
although this connection has specific output and cable parameters.

26 Micro Motion Compact Density Meter 7835/7845 Retrofit

RS-485 output and cable entity parameters (MTL7761AC)Table 4-3:

Input parameters

Voltage (Ui) 18 VDC

Current (Ii) 100 mA

Internal capacitance (Ci) 1 nF

Internal inductance (Li) 0.0 H

Output parameters

Voltage (Uo) 9.51 VDC

Current (instantaneous) (Io) 480 mA

Current (steady state) (I) 106 mA

Power (Po) 786 mW

Internal resistance (Ri) 19.8 Ω

Cable parameters for Group IIC

External capacitance (Co) 85 nF

External inductance (Lo) 154 µH

External inductance/resistance ratio (Lo/Ro) 31.1 µH/Ω

Wiring

Cable parameters for Group IIB

External capacitance (Co) 660 nF

External inductance (Lo) 610 µH

External inductance/resistance ratio (Lo/Ro) 124.4 µH/Ω

Hazardous area
voltage

Hazardous area
current

The meter entity parameters require the selected barrier’s open­circuit voltage to be limited to less than 30 VDC (Vmax = 30 VDC).

The meter entity parameters require the selected barrier’s short­circuit currents to sum to less than 484 mA (Imax = 484 mA) for all
outputs.

Hazardous area
capacitance

The capacitance (Ci) of the meter is 0.0011 μF. This value added to
the wire capacitance (Ccable) must be lower than the maximum
allowable capacitance (Ca) specified by the safety barrier. Use the
following equation to calculate the maximum length of the cable
between the meter and the barrier: Ci + Ccable ≤ Ca

Hazardous area
inductance

The inductance (Li) of the meter is 0.0 μH. This value plus the field
wiring inductance (Lcable), must be lower than the maximum
allowable inductance (La) specified by the safety barrier. The
following equation can then be used to calculate the maximum cable
length between the meter and the barrier: Li + Lcable ≤ La

Installation Manual 27

Wiring

4.5.2 Wire all intrinsically safe outputs using safety barriers

Micro Motion provides a safety barrier installation kit for wiring the meter in a hazardous
area. Contact your local sales representative or customer support at

[e-mail] for more information on ordering a barrier kit.

CAUTION!

• Meter installation and wiring should be performed by suitably trained personnel only in

accordance with the applicable code of practice.

• Refer to the hazardous area approvals documentation shipped with your meter. Safety

instructions are available on the Product Documentation DVD and accessible at

www.emerson.com.

The safety barrier kit provides barriers for connecting all of the available meter outputs.
Use the provided barriers with the designated output.

Output(s)

4–20 mA MTL7728P+

• 4–20 mA

• Time Period Signal (TPS)

• Discrete

Modbus/RS-485 MTL7761AC

Power MTL7728P+

Barrier

MTL7728P+

Procedure

Wire the barriers to the appropriate output terminal and pins (see Figure 4-3).

28 Micro Motion Compact Density Meter 7835/7845 Retrofit

Bus
Bar

Hazardous Area

Non-Hazardous Area

MTL7761AC

RS-485 A

RS-485 B

3

4

1

2

24 VDC

24 VDC

MTL7728P+

24 VDC

3

4

1

2

MTL7728P+

3

4

1

2

250 Ω

MTL7728P+

3

4

1

2

A

B

C

mA1+

HART

RS-485

PWR

mA2/

TPS/DO

A
B

Wiring

Intrinsically safe mA/DO/TPS output wiring using safety barriersFigure 4-3:

A. HART/Field Communicator device
B. Signal device
C. The recommended resistance will vary depending on your Channel B output. For mA outputs, 250 Ω is the recommended

resistance. For TPS or Discrete outputs, 500–1000 Ω is the recommended resistance.

CAUTION!

• In an electrically noisy environment, screen the cable in a safe area.

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable instrumentation cable to connect

the meter. The instrumentation cable should have individual screens, foil or braid over each twisted pair, and an
overall screen to cover all cores. Where permissible, connect the overall screen to earth at both ends (360° bonded at
both ends). Connect the inner individual screens at only the controller end.

• For safety, do not terminate the inner individual screens to earth in a hazardous area.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable ports with metal blanking

plugs.

Installation Manual 29

Wiring

4.5.3 Wire the intrinsically safe Analog outputs version using galvanic isolators

Micro Motion provides a galvanic isolator installation kit specific to wiring the Analog
version of the meter in a hazardous area. Contact your local sales representative or
Micro Motion Customer Support at [e-mail] for more information on
ordering an isolator kit for your meter.

CAUTION!

• Meter installation and wiring should be performed by suitably trained personnel only in

accordance with the applicable code of practice.

• Refer to the hazardous area approvals documentation shipped with your meter. Safety

instructions are available on the Micro Motion Product Documentation DVD and
accessible on the Micro Motion website at www.emerson.com.

The galvanic isolator kit (Analog version) provides isolators for connecting the following
outputs. Use the provided isolators with the designated output.

Note

The RS-485 barrier is not isolated.

Output(s)

4–20 mA + HART MTL5541

4–20 mA MTL5541

Modbus/RS-485 MTL7761AC

Power MTL5523

Isolator

Procedure

Wire the isolators to the appropriate output terminal and pins (see Figure 4-4).

30 Micro Motion Compact Density Meter 7835/7845 Retrofit

mA1+
HART

PWR

mA2

Hazardous Area

Non-Hazardous Area

MTL7761AC

RS-485 A

RS-485 B

3

4

1

2

MTL5541

2

1

14

13

12

11

MTL5523

2

1

24 VDC

14

13

12

11

24 VDC

LINK

250 Ω

MTL5541

2

1

14

13

12

11

24 VDC

250 Ω

A
B

A

B

Wiring

Intrinsically safe output wiring using galvanic isolators (mA outputs option)Figure 4-4:

A. HART/Field Communicator device
B. Signal device

CAUTION!

• In an electrically noisy environment, screen the cable in a safe area.

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable instrumentation cable to connect

the meter. The instrumentation cable should have individual screens, foil or braid over each twisted pair, and an
overall screen to cover all cores. Where permissible, connect the overall screen to earth at both ends (360° bonded at
both ends). Connect the inner individual screens at only the controller end.

• For safety, do not terminate the inner individual screens to earth in a hazardous area.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable ports with metal blanking

plugs.

Installation Manual 31

Wiring

4.5.4 Wire the intrinsically safe Time Period Signal (TPS) or Discrete output version using galvanic isolators

Micro Motion provides a galvanic isolator installation kit specific to wiring the Time Period
Signal (TPS) and Discrete versions of the meter in a hazardous area. Contact your local
sales representative or Micro Motion Customer Support at [e-mail] for
more information on ordering an isolator kit for your meter.

CAUTION!

• Meter installation and wiring should be performed by suitably trained personnel only in

accordance with the applicable code of practice.

• Refer to the hazardous area approvals documentation shipped with your meter. Safety

instructions are available on the Micro Motion Product Documentation DVD and
accessible on the Micro Motion website at www.emerson.com.

The galvanic isolator kit (TPS/Discrete version) provides isolators for connecting the
following outputs. Use the provided isolators with the designated output.

Note

The RS-485 barrier is not isolated.

Output(s)

4–20 mA + HART MTL5541

• Time Period Signal (TPS)

• Discrete

Modbus/RS-485 MTL7761AC

Power MTL5523

Isolator

MTL5532

Procedure

1. Wire the isolators to the appropriate output terminal and pins (see Figure 4-5).

32 Micro Motion Compact Density Meter 7835/7845 Retrofit

mA1+

HART

RS-485

PWR

TPS/DO

SIG

Hazardous Area

Non-Hazardous Area

MTL7761AC

MTL5532

RS-485 A

RS-485 B

5

3

4

1

2

1

11

12

13

14

4

1 kΩ

MTL5541

2

1

14

13

12

11

A

24 VDC

24 VDC

1 kΩ

250 Ω

B

A
B

MTL5523

2

1

14

13

12

11

24 VDC

LINK

Wiring

Hazardous area output wiring using galvanic isolators (TPS and Discrete output options)Figure 4-5:

A. HART/Field Communicator
B. Signal device

CAUTION!

• In an electrically noisy environment, screen the cable in a safe area.

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable instrumentation cable to connect

the meter. The instrumentation cable should have individual screens, foil or braid over each twisted pair, and an
overall screen to cover all cores. Where permissible, connect the overall screen to earth at both ends (360° bonded at
both ends). Connect the inner individual screens at only the controller end.

• For safety, do not terminate the inner individual screens to earth in a hazardous area.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable ports with metal blanking

plugs.

Installation Manual 33

1 2 3 4

OFF
ON

Wiring

2. Set the isolator switch settings for the TPS/DO connection (MTL5532 isolator). You

must set the isolator switches appropriately for Pins 1 through 5 (see Table 4-4).

The switches are located on the side of the isolator, and must be set to either Off
(the up position) or On (the down position).

MTL5532 switch location (plus ON/OFF switch position)Figure 4-6:

MTL5532 switch settingsTable 4-4:

Switch ON/OFF?

1 ON

2 OFF

3 OFF

4 OFF

4.6 Processor wiring for remote-mount 2700
FOUNDATION™ fieldbus option

4.6.1 RS-485 entity parameters for the remote-mount 2700
FOUNDATION™ fieldbus option

DANGER!

Hazardous voltage can cause severe injury or death. To reduce the risk of hazardous voltage,
shut off power before wiring the meter.

34 Micro Motion Compact Density Meter 7835/7845 Retrofit

Wiring

DANGER!

Improper wiring in a hazardous environment can cause an explosion. Install the meter only in
an area that complies with the hazardous classification tag on the meter.

RS-485 output and cable entity parametersTable 4-5:

Cable parameters for intrinsically safe circuit (linear)

Voltage (Ui) 17.22 VDC

Current (Ii) 484 mA

Maximum capacitance (Ci) 1 nF

Maximum inductance (Li) Negligible

Cable parameters for Ex ib IIB, Ex ib IIC

Voltage (Uo) 9.51 VDC

Current (instantaneous) (Io) 480 mA

Current (steady state) (I) 106 mA

Power (Po) 786 mW

Internal resistance (Ri) 19.8 Ω

Cable parameters for Group IIC

Maximum external capacitance (Co) 85 nF

Maximum external inductance (Lo) 25 µH

Maximum external inductance/resistance ratio
(Lo/Ro)

Cable parameters for Group IIB

Maximum external capacitance (Co) 660 nF

Maximum external inductance (Lo) 260 µH

Maximum external inductance/resistance ratio
(Lo/Ro)

4.6.2 Connect 4-wire cable

4-wire cable types and usage

Micro Motion offers two types of 4-wire cable: shielded and armored. Both types contain
shield drain wires.

The cable supplied by Micro Motion consists of one pair of red and black 18 AWG
(0.75 mm2 ) wires for the VDC connection, and one pair of white and green 22 AWG
(0.35 mm2 ) wires for the RS-485 connection.

31.1 µH/Ω

124.4 µH/Ω

User-supplied cable must meet the following requirements:

• Twisted pair construction.

Installation Manual 35

Wiring

• Applicable hazardous area requirements, if the core processor is installed in a

hazardous area.

• Wire gauge appropriate for the cable length between the core processor and the

transmitter.

• Wire gauge of 22 AWG or larger, with a maximum cable length of 1000 feet.

Prepare a cable with a metal conduit

Prerequisites

Note

If you are installing unshielded cable in continuous metallic conduit with 360º termination shielding,
you only need to prepare the cable – you do not need to perform the shielding procedure.

Procedure

1. Remove the integral processor cover using a flat-blade screw driver.

2. Run the conduit to the sensor.

3. Pull the cable through the conduit.

4. Cut the drain wires and let them float at both ends of the conduit.

Prepare a cable with user-supplied cable glands

Prerequisites

Important

For user-supplied cable glands, the gland must be capable of terminating the drain wires.

Procedure

1. Remove the core processor cover using a flat-blade screw driver.

2. Pass the wires through the gland.

3. Terminate the shield and drain wires inside the gland.

4. Assemble the gland according to vendor instructions.

Prepare a cable with Micro Motion-supplied cable glands

1. Remove the core processor cover using a flat-blade screw driver.

2. Pass the wires through the gland nut and clamping insert.

A. Gland nut
B. Clamping insert

36 Micro Motion Compact Density Meter 7835/7845 Retrofit

3. Strip the cable jacket.

Option Description

NPT gland type Strip 4-1/2 inch (115 mm)

M20 gland type Strip 4-1/4 inch (108 mm)

4. Remove the clear wrap and filler material.

5. Strip most of the shielding.

Option Description

NPT gland type Strip all but 3/4 inch (19 mm)

M20 gland type Strip all but 1/2 inch (12 mm)

6. Wrap the drain wires twice around the shield and cut off the excess drain wires.

Wiring

A. Drain wires wrapped around shield

7. For foil (shielded cable) only:

Note

For braided (armored cable) skip this step and contine to the next step.

Option

NPT
gland
type

Description

a. Slide the shielded heat shrink over the drain wires. Ensure that the wires are

completely covered.
b. Apply heat (250 °F or 120 °C) to shrink the tubing. Do not burn the cable.
c. Position the clamping insert so the interior end is flush with the braid of the

heat shrink.

A. Shielded heat shrink
B. After heat is applied

Installation Manual 37

Wiring

Option Description

M20
gland
type

8. Assemble the gland by folding the shield or braid back over the clamping insert and
1/8 inch (3 mm) past the O-ring.

A. Shield folded back

Trim 0.3 in (7 mm).

A. Trim

4.6.3

9. Install the gland body into the conduit opening on the core processor housing.

10. Insert the wires through the gland body and tighten the gland nut onto the gland
body.

A. Shield folded back
B. Gland body

Processor wiring for the remote-mount 2700
FOUNDATION fieldbus™ option

The following figure illustrates how to connect the individual wires of a 4-wire cable to the
processor terminals. For detailed information on mounting and wiring to the remote­mount 2700 FOUNDATION fieldbus transmitter, see the transmitter installation manual.

38 Micro Motion Compact Density Meter 7835/7845 Retrofit

A

B
C

D

Wiring

Figure 4-7:

A. White wire to RS-485/A terminal
B. Green wire to RS-485/B terminal
C. Red wire to Power supply (+) terminal
D. Black wire to Power supply (–) terminal

Important

• To meet the EC Directive for EMC (Electromagnetic Compatibility), it is recommended that the

• Metal cable glands should be used where the cables enter the meter amplifier box. Unused cable

Processor (Modbus/RS-485) connections to the remote-mount 2700 FF
transmitter

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 end.

ports should be fitted with metal blanking plugs.

4.7

Wiring to signal converters and/or flow computers

For meters with a Time Period Signal (TPS) output, you can wire the meter to an signal
converter or flow computer directly. The following information provides wiring diagrams
for making those connections in safe and hazardous environments.

When wiring the meter to an active HART host or signal converter/flow computer, you are
not required to provide external power to the output connections. These active devices
provide the 24 VDC necessary for these connections.

Installation Manual 39

mA1+

HART

RS-485

PWR

TPS

AA
B

24 VDC

RS-485 A

RS-485 B

A

B

Wiring

4.7.1 Wire to a signal converter/flow computer in an explosion-proof/flameproof or non-hazardous area

Figure 4-8:

Wiring to a signal converter/flow computer in an explosion-proof/
flameproof or non-hazardous area

A. Active HART host
B. Active signal converter/flow computer

CAUTION!

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable

instrumentation cable to connect the meter. The instrumentation cable should have
individual screens, foil or braid over each twisted pair, and an overall screen to cover all
cores. Where permissible, connect the overall screen to earth at both ends (360° bonded at
both ends). Connect the inner individual screens at only the controller end.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable

ports with metal blanking plugs.

40 Micro Motion Compact Density Meter 7835/7845 Retrofit

4.7.2 Wire to a signal converter/flow computer in an

mA1+

HART

RS-485

PWR

TPS

AA
B

Hazardous Area

Non-Hazardous Area

MTL7761AC

RS-485 A

RS-485 B

3

4

1

2

24 VDC

MTL7728P+

3

4

1

2

MTL7728P+

3

4

1

2

MTL7728P+

3

4

1

2

A

B

intrinsically safe area

Wiring to a signal converter/flow computer in an intrinsically safe areaFigure 4-9:

Wiring

A. Active HART host
B. Active signal converter/flow computer

CAUTION!

• In an electrically noisy environment, screen the cable in a safe area.

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable

instrumentation cable to connect the meter. The instrumentation cable should have
individual screens, foil or braid over each twisted pair, and an overall screen to cover all
cores. Where permissible, connect the overall screen to earth at both ends (360° bonded at
both ends). Connect the inner individual screens at only the controller end.

• For safety, do not terminate the inner individual screens to earth in a hazardous area.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable

ports with metal blanking plugs.

Installation Manual 41

Grounding

5 Grounding

The meter must be grounded according to the standards that are applicable at the site.
The customer is responsible for knowing and complying with all applicable standards.

Prerequisites

Micro Motion suggests the following guides for grounding practices:

• In Europe, EN 60079-14 is applicable to most installations, in particular Sections

12.2.2.3 and 12.2.2.4.

• In the U.S.A. and Canada, ISA 12.06.01 Part 1 provides examples with associated

applications and requirements.

• For IECEx installations, IEC 60079-14 is applicable.

If no external standards are applicable, follow these guidelines to ground the meter:

• Use copper wire, 18 AWG (0.75 mm2) or larger wire size.

• Keep all ground leads as short as possible, less than 1 Ω impedance.

• Connect ground leads directly to earth, or follow plant standards.

CAUTION!

Ground the meter to earth, or follow ground network requirements for the facility. Improper
grounding can cause measurement error.

Procedure

Check the joints in the pipeline.

- If the joints in the pipeline are ground-bonded, the sensor is automatically grounded

and no further action is necessary (unless required by local code).

- If the joints in the pipeline are not grounded, connect a ground wire to the grounding

screw located on the sensor electronics.

42 Micro Motion Compact Density Meter 7835/7845 Retrofit

Grounding

Installation Manual 43

*MMI-20020999*

MMI-20020999

Rev AC

2018

Micro Motion Inc. USA

Worldwide Headquarters
7070 Winchester Circle
Boulder, Colorado USA 80301
T [phone]
T [phone]
F [phone]

www.emerson.com

Micro Motion Asia

Emerson Automation Solutions
1 Pandan Crescent
Singapore 128461
Republic of Singapore
T [phone]
F [phone]

©

2018 Micro Motion, Inc. All rights reserved.

The Emerson logo is a trademark and service mark of Emerson Electric Co. Micro Motion, ELITE,
ProLink, MVD and MVD Direct Connect marks are marks of one of the Emerson Automation
Solutions family of companies. All other marks are property of their respective owners.

Micro Motion Europe

Emerson Automation Solutions
Neonstraat 1
6718 WX Ede
The Netherlands
T [phone]
F [phone]

www.micromotion.nl

Micro Motion United Kingdom

Emerson Automation Solutions
Emerson Process Management Limited
Horsfield Way
Bredbury Industrial Estate
Stockport SK6 2SU U.K.
T [phone]
F [phone]

Micro Motion Japan

Emerson Automation Solutions
1-2-5, Higashi Shinagawa
Shinagawa-ku
Tokyo 140-0002 Japan
T [phone]
F [phone]