Manuals & Guides: 7835 Explosion Proof Liquid Density Meters | Micro Motion
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Installation & Configuration Manual
P/N MMI-20015053, Rev. AC
February 2011
Micro Motion 7835
Explosion Proof Liquid
Density Meters
Standard Electronics
©2011, 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 Process Management family of
companies. All other marks are property of their respective owners.
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 cannot be held responsible for any errors, omissions, or other misinformation contained herein. No part of this
document may be photocopied or reproduced without prior written consent of Micro Motion.
Contents
Chapter 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Safety guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Product overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Product range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Electronics product range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5 2004/22/EC (MID) applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 2 Installation Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.1 General information applicable to the complete system . . . . . . . . . . . . . . 5
2.2.2 Pressure bearing parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Installation planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Meter mounting and pipework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.5 Pressure drop in the meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.6 Calculation of pressure drop in the meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.7 Post-installation checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.8 Installation drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 3 Electrical Connections (Standard). . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 MID (2004/22/EC) Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.1 Securing the meter for MID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Ground connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4 Use with Micro Motion signal converters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4.1 System connections (Safe Area only) . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.5 Use with customer’s own equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.5.1 System connections (Safe Area only) . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.6 Post-installation checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Chapter 4 Calibration and Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Interpretation of calibration certificate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.1 General density equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.2 Temperature correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.3 Pressure correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.4 Velocity of sound correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.3.1 Factory calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.3.2 Calibration of transfer standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.3.3 Instrument calibration certificate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.3.4 Pressure test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.3.5 Insulation test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.3.6 Calibration check methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Installation & Configuration Manual 3
Contents
4.4 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Chapter 5 General Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.2 Fault analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.3 General maintenance procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.4 Physical checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.4.1 Check calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5.4.2 Remedial servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Appendix A 7835 Explosion Proof (Exd) Specifications . . . . . . . . . . . . . . . . . . . 33
A.1 Density performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
A.2 Temperature specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
A.3 Pressure ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
A.4 Hazardous area classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
A.5 OIML R117-1 classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
A.6 Electromagnetic compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
A.7 Materials of construction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.8 Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.9 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.10 Safety approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Appendix B Electronics Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
B.1 Standard Electronics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
B.1.1 Meter Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
B.1.2 Output Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
B.2 Environmental Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
B.2.1 Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
B.2.2 IP rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Appendix C Calibration Certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
C.1 Example calibration certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Appendix D Return Policy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
D.1 General guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
D.2 New and unused equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
D.3 Used equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4 Micro Motion 7835 Explosion Proof Liquid Density Meters
Chapter 1
Introduction
1.1 Safety guidelines
Handle the 7835 Explosion Proof Liquid Density meter with great care.
• Do not drop the meter or subject it to severe mechanical shock.
• Do not expose the meter to excessive vibration.
• Ensure axial loading from pipework does not exceed 1/2 tonne.
• Ensure all electrical safety requirements are applied.
• Ensure the meter and associated pipework have been pressure tested to 1-1/2 times the
maximum operating pressure.
• Do not use liquids incompatible with the construction.
• Do not operate the meter above its rated pressure.
• Do not expose the meter to excessive vibration (> 0.5 g continuous).
• Ensure meter is not transported when it contains hazardous substances. This includes fluids
that may have leaked into, and are still contained, within the case.
• To return a meter, refer to Appendix D for more information on the Micro Motion return
policy.
Safety messages are provided throughout this manual to protect personnel and equipment. Read each
safety message carefully before proceeding to the next step.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
1.2 Product overview
This meter will provide a continuous on-line measurement of density and temperature of the process
fluid being measured. The construction of the meter is to explosion proof standards, allowing
installation in hazardous areas. Operational parameters can be found in the product specification.
Installation & Configuration Manual 1
Introduction
SUPPLY
PRT
Figure 1-1 Sideways view of the 7835 Explosion Proof Liquid Density meter
Liquid density is determined from the resonant frequency of a vibrating tube containing the liquid,
and liquid temperature is determined from a 100 Ω RTD .
1.3 Product range
The product range is summarized in Table 1-1. The meters are identical mechanically, except for the
material used in the wetted parts, and the flanges/couplings. A fully welded design is utilized to
ensure maximum reliability in the most severe environments. In the unlikely event of a leak occurring
in the center tube assembly, the outer casing will withstand a line pressure rating of up to 100 bar
(1450 psi).
Table 1-1. 7835 Explosion Proof Liquid Density meter range
Meter Tube material Features
7835 Ni-Span-C
©
Low temperature coefficient and long term stability, appropriate for fiscal
applications.
1.4 Electronics product range
The 7835 Explosion Proof Liquid Density meter has the following electronics.
Table 1-2. Standard electronics board
Standard Electronics
Density version • Basic amplifier circuit providing a frequency
signal (indicating liquid density) and RTD
resistance (indicating liquid temperature).
• Interfaces with a Micro Motion
Converter or Flow Computer.
• Features 6 screw-terminals for power in, and
outputs.
®
Signal
2 Micro Motion 7835 Explosion Proof Liquid Density Meters
Introduction
1.5 2004/22/EC (MID) applications
Mobrey Limited, a division of Emerson Process Management, has evaluated the 7835 and 7845 liquid
density meters against OIML R117-1:2007 and WELMEC guide 8.8 for use in measuring systems for
the continuous and dynamic measurement of quantities of liquids other than water. This evaluation
was in compliance with the European Measuring Instrument directive (2004/22/EC) annex MI-005.
You may use the evaluation certificate for the 7835 liquid density meter, with written permission of
Mobrey Limited to assist in obtaining an EC-type examination certificate for the complete measuring
system.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
Installation & Configuration Manual 3
Introduction
4 Micro Motion 7835 Explosion Proof Liquid Density Meters
Chapter 2
Installation Procedure
2.1 General
This chapter describes the mechanical installation of the 7835 Explosion Proof Liquid Density meter.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
2.2 Safety Information
2.2.1 General information applicable to the complete system
• These safety instructions are to be used whenever handling or operating this product. Suitably
trained personnel shall carry out the installation both mechanical and electrical in accordance
with the applicable local and national regulations and codes of practice for each discipline.
• Safe working practices for the media and process concerned must be followed during the
installation and maintenance of the equipment. Depressurize and isolate the system before
starting to loosen or remove any connection.
• If the equipment is likely to come into contact with aggressive substances, it is the
responsibility of the user to take suitable precautions that prevent it from being adversely
affected.
• It is the responsibility of the installer/user of this equipment to ensure:
• This product is not used as a support for other equipment or personnel.
• This product is protected from impact.
• It is important that this sensor is handled with care due to its weight and sensitivity to impact;
ensure lifting straps are fitted around flanged ends.
Installation & Configuration Manual 5
Installation Procedure
2.2.2 Pressure bearing parts
• It is the responsibility of the installer/user of this equipment to ensure:
• The materials of construction are suitable for the application.
• All piping connections conform to the local and national regulations and codes of practice.
• The pressure and temperature limits for this equipment are not exceeded, if necessary by
the use of suitable safety accessories. See Table 2-1.
Table 2-1 Pressure ratings: 316/316L dual-rated stainless steel
Process
Flange fitting
Class 600 1440.2 psi (99.3 bar) 1203.8 psi (83.0 bar)
PN40 580.2 psi (40.0 bar) 539.5 psi (37.2 bar)
PN100 1450.4 psi (100.0 bar) 1348.9 psi (93.0 bar)
Pressure Rating
20°C 110°C
• Correct gaskets/seals are fitted and are compatible with the media and process.
• The installed sensor is adequately supported for weight and vibration effects.
• Personnel are protected from hot burns by guards, thermal lagging or limited access.
Allow time to cool prior to carrying out maintenance operations. It is recommended that
“HOT” notices are fitted in the vicinity of the equipment where applicable.
• Regular inspection for corrosion and wear are carried out, both internal and external.
• The sensor must not be fitted until all installation work and final pre commissioning checks are
carried out. Do not remove blanking plugs until the sensor is fitted.
• The sensor must be installed in compliance with this manual, to ensure correct fitting. This
applies to all variants.
• The user should not repair this equipment, but general maintenance can be applied as
described within this manual.
6 Micro Motion 7835 Explosion Proof Liquid Density Meters
Installation Procedure
2.3 Installation planning
When planning the installation of a meter, it is important to consider the following factors:
Table 2-2. Installation considerations
Safety
Serviceability
When installing in a process line, it is important that the construction material of the wetted
parts (tube) is matched to the non-corrosive performance of the liquid passing through the
instrument. Failure to observe this requirement can cause deterioration of the central tube
(the bellows) and loss in measurement accuracy, or even a failure if leaking occurs. For
advice on which meter in the range is appropriate, please contact Micro Motion.
The NI-SPAN-C material of the central tube is not rated for ‘sour’ service as defined in
NACE specification MR0103-2005. For advice in this application, please contact
Micro Motion.
Installing the meter in a by-pass configuration allows it to be removed for servicing or
calibration without affecting the main pipeline. Possible by-pass configurations are shown in
Figure 2-3.
Performance
Pipe stresses and
vibration
Gas bubbles The presence of gas bubbles can seriously affect the meter performance and so the
Meter orientation • For low flow rates, for example 750 liters/hour (2.7 gal/min.), the meter should preferably
Flow rate A fast flow rate, for example 3000 liters/hour (11 gal/min.), will help to achieve good
Temperature stability Thermally lag the meter and the inlet and slipstream/bypass-loop pipework to ensure good
Axial load should not exceed ½ tonne, so pipe-work should have a degree of flexibility.
Excessive pipe vibration should be avoided. Figure 2-2 for preferable mounting positions.
following points should be considered:
• The liquid must always be at a pressure substantially above its vapor pressure.
• All pipe-work couplings and joints must be airtight.
• No vortex should be present at the inlet to the meter.
• Cavitations, caused by pumping, should not generate bubbles from dissolved gases.
• If a pump is used it should ‘push’ rather than ‘pull’ the product through the meter.
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
minimizing the ingress of water should a cable gland become defective.
temperature equilibrium and have a self-cleaning action.
A low flow rate, for example 1000 liters/hour (3.7 gal/min.), is recommended if the product
contains particles which may cause erosion.
The meters exhibit a small flow dependent density reading. For flow rates up to 15000
liters/hour (55 gal/min) and assuming no consequent line pressure or product changes, the
maximum density offset will be less than 0.2 kg/m
temperature stabilisation.
3
.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
2.4 Meter mounting and pipework
This section considers in more detail the mounting of the meters and the design of the associated
pipework, including the calculation of pressure drop in the meter.
The preferred methods of supporting the meter are shown in Figure 2-1.
Installation & Configuration Manual 7
Installation Procedure
Figure 2-1 Preferred methods of mounting meters (support)
For continuously high flow rates, the mounting position can be selected to simplify the associated
pipework and help minimize the pressure and temperature losses (see Figure 2-2).
8 Micro Motion 7835 Explosion Proof Liquid Density Meters
Installation Procedure
Figure 2-2 Preferred methods of mounting meter (angles)
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
Installation & Configuration Manual 9
Installation Procedure
Figure 2-3 Typical bypass pipeline configurations
10 Micro Motion 7835 Explosion Proof Liquid Density Meters
Installation Procedure
h
200 f
×L×
V
2
×ρ×
gD
×
------------------------ --------------------------
=
2.5 Pressure drop in the meter
The pressure drop in the meter depends on:
• Flow rate (V), and
• Kinematic viscosity (
υ)
Table 2-3. Pressure drop at various flow rates
Flow Rate Flow Velocity Pressure Drop
(liters/hour) (V m/s)
1000 0.6 0.003 0.004
4000 2.5 0.033 0.048
12000 7.6 0.238 0.345
(1) Indicates laminar flow (fluid density 1.0 g/cc)
υ = 2 cS u = 10 cS
2.6 Calculation of pressure drop in the meter
The meter should be considered as a straight pipe of 23.6 mm (0.929”) internal diameter and 1.03 m
(40.551”) in length. The following formula has been proven to apply to the meter by measurements at
12000 liters/hour (44 gal/min).
Where:
• h = Pressure drop (bars)
• f = Friction coefficient
• L = Pipe length (m) = 1.03 mm
• D = Internal pipe diameter (mm) = 23.6 mm
• V = Mean fluid velocity (m/s)
(1)
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
•
ρ
= Fluid density (g/cc)
• g = 9.81 (m/s
For viscous or laminar flow (Reynolds Number R
• Frictional Coefficient (f) = 16
2
)
less than 2000):
e
÷ R
e
For turbulent flow (Re greater than 2500):
• Frictional Coefficient (f) = 0.064
Where, pipe R
= 1000 x V x D ÷ υ [υ = kinematic viscosity (cS)]
e
÷ R
e
0.23
In addition to the pressure drop caused by the liquid flow through the instrument, it will be necessary
to calculate the pressure drop in any associated sample pipework before concluding the system design
requirements.
2.7 Post-installation checks
After installation, the meter should be pressure tested to 1.5 times the maximum working pressure of
the system but not to a value exceeding the meter test figure shown on the meter label.
If the pressure test figure is exceeded, the meter may be irrevocably damaged.
Installation & Configuration Manual 11
Installation Procedure
2.8 Installation drawings
Figure 2-4. Installation drawing for 7835 with standard electronics
12 Micro Motion 7835 Explosion Proof Liquid Density Meters
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