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
Chapter 3
Electrical Connections (Standard)
3.1 General
This chapter describes the electrical installation of the 7835 Explosion Proof Liquid Density meters
with Standard Electronics fitted.
3.2 MID (2004/22/EC) Requirements
To comply with the MID (2004/22/EC) directive:
• Unused cable ports must be sealed with suitably rated blanking plugs.
• After commissioning or maintenance of the meter, you must seal the enclosure cover to secure
legally relevant parameters from unauthorized modification.
See Section 3.2.1 for more information on securing the meter from unauthorized access to the
meter controls.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
3.2.1 Securing the meter for MID
To seal the meter from unauthorized access after commissioning or maintenance, Micro Motion has
provided additional holes on the electronics housing cover to attach a locking wire to the transmitter
cover. The securing component must bear the mark as laid down by the national inspection authority.
Figure 3-1 illustrates the suggested method for sealing the meter.
Note: When installing the meter in a MID measuring system, you must consider the method in which
the system will be verified to meet MID requirements. This method may impact the design of the
measurement system, and we recommend you involve the national inspection authority early in the
design process.
Installation & Configuration Manual 13
Electrical Connections (Standard)
Use hole in lid(s) to attach locking wire
Stainless steel locking wire
(supplied by MID inspector)
Bonding crimp
(supplied by MID inspector)
Figure 3-1 MID seal method
3.3 Ground connections
There are two earth-bonding points for the meter. One bonding point is located inside the aluminium
enclosure for the maintaining amplifier housing. The second bonding point is located on the end plate
of the meter body.
The 0 volt power supply lead should be earthed at the supply end.
3.4 Use with Micro Motion signal converters
When operated in conjunction with a flow computer or signal converter, only the meter can be
operated in the hazardous area. The flow computer (or signal converter) must be sited in a safe area
only.
3.4.1 System connections (Safe Area only)
The density system connections are illustrated in Figure 3-2.
14 Micro Motion 7835 Explosion Proof Liquid Density Meters
Electrical Connections (Standard)
Figure 3-2 Electric connection diagram to signal converters
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
3.5 Use with customer’s own equipment
3.5.1 System connections (Safe Area only)
• Power supply to density meter: 15.5 V to 33 V dc, 25 mA minimum
• Power supply to RTD: 5 mA maximum
The frequency at which the meter is operating can be detected by using a series resistor in the +VE
power line. The value of resistance to be used for a given supply voltage must not exceed the value
obtained from the LOAD NOMOGRAM (Figure 3-4). The electrical connections to be made are
shown in Figure 3-3.
Installation & Configuration Manual 15
Electrical Connections (Standard)
7835/45/46/47 with
Standard Electronics
PRT
1
2
3
4
5
6
See Note
POWER +VE
SIGNAL +VE
POWER −VE
SIGNAL −VE
PRT SUPPLY +VE
PRT SIGNAL
PRT SUPPLY −VE
Figure 3.2 - Electrical Connection Diagram
7835/45/46/47 with Standard Electron ic s to Cu stomer’s Own Equipment
R
POS +
NEG -
SIG
Note: See Load Nomogram (Figure 3.3) to determine R value.
1μF
1μF
Meter
RTD
Figure 3.3 Load Resistance Nomogram
Supply Voltage (volts d.c.)
15
20
25
30
(33)
35
Maximum Supply Voltage ‘E’
0
100
200
300
400 500 600
700
Lo
a
d
R
e
s
is
ta
nc
e
L
i
n
e
Supply Voltage
Maximum Load Resistance
for Given Supply Voltage
Maximum Load Resistance (ohms)
Note: It is recommended that the actual load resistor should
be 50 ohms less than that given by the Nomogram.
Figure 3-3 Electrical connection diagram to customer’s own equipment
Figure 3-4 Load resistance
16 Micro Motion 7835 Explosion Proof Liquid Density Meters
Electrical Connections (Standard)
3.6 Post-installation checks
After installation, the following procedure will indicate to a high degree of confidence that the meter
is operating correctly.
Measure the current consumption and the supply voltage at the meter amplifier. This should be within
the limits:
• 15.5 V to 30 Vdc, 17 mA
±1 mA
With the meter empty, clean and dry, measure the periodic time of the output signal and check that it
is as specified on the meter calibration certificate (air check), to within the limits given in the table
below.
Meter type Air check limit at 20°C Added temperature effect
7835 ±60 ns ±10 ns/°C
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
Installation & Configuration Manual 17
Electrical Connections (Standard)
18 Micro Motion 7835 Explosion Proof Liquid Density Meters
Chapter 4
The general density equation is: D = KK K01 2
2
++
ττ
Where :
D = Th e un cor recte d d ensi ty (kg/m
3
) of liqui d
τ
= Periodic time (μs) of v ibration
= 1/f where ‘f’’ is the frequency of vibration
2&1,0 KKK = Constants fr om the Calibration Certi ficate
Calibration and Performance
4.1 General
The 7835 Explosion Proof Liquid Density meter is calibrated at the factory and is supplied with its
own test and calibration certificate (see Appendix C for examples). This certificate specifies the
various calibration constants that allow the user to convert the output periodic time signal from the
meter into a density value.
4.2 Interpretation of calibration certificate
4.2.1 General density equation
The basic meter constants, K0, K1, and K2 are computed from the factory calibration on three fluids.
Using these constants and the general density equation, the density of the liquid within the meter can
be calculated.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
It is stated on the calibration certificate that the basic constants are determined from a calibration at a
temperature of 20 °C (68 °F) and at a pressure of 1 bar (14.5 psi). If the operating conditions of the
meter differ from that of the calibration conditions, a correction to the density calculated using the
general equation is required.
Installation & Configuration Manual 19
Calibration and Performance
The e qua tion used for thi s cor recti on is :
D
t
=
()
[]
()
DKt Kt11820 1920+−+−
Where:
D
t
= Te m per ature co rrec ted d ensity (kg/ m3)
D = Dens i ty ca lc ulat ed using eq uat ion 1
t = Temperature (degrees C)
K and K18 19 = Constants from the Calibration Certificate
-10
0
10
20
30
40
50
0 20 40 60 80 100 120 140
Pressu re ( Bar Absolute)
Density Offset (kg/m
3
)
Uncorrected pressure effects
on the meter fall within these
bands
4.2.2 Temperature correction
If the meter operates at temperatures other than 20 °C (68 °F), a correction to the density calculated
using equation (1) must be made using the temperature coefficient data given on the calibration
certificate.
4.2.3 Pressure correction
The meter design has a unique facility to reduce the influence of the line pressure on the density
measurement but there is a residual effect for which correction may be required. This residual
pressure effect before a pressure correction is illustrated for the 7835 Exd meter in the following
figures.
Figure 4-1 Pressure effect on the7835 Exd meter before pressure correction (at 20°C)
20 Micro Motion 7835 Explosion Proof Liquid Density Meters
Calibration and Performance
The equation used to apply pressure correction is:
D
P
=
()
[]
()
DKP KP
t
1201 211+−+−
Where:
D
P
= Te m per ature an d pressure cor recte d d ensity (kg/m3)
D
t
= Te m per ature co rrec t ed d ensity (kg/m3)
P = Pressure in bar absolute
K20 =
()
KAKBP20 20 1+−
K21 =
()
KAKBP21 21 1+−
During the calibration of the meter, which is normally performed at a pressure of 1 bar (14.5 psi), the
pressure influence is also measured. This data is also shown on the calibration certificate (see
Appendix C).
Note: K20A, K20B, K21A, and K21B are the pressure coefficient constants on the calibration
certificate.
Note: The pressure correction is further enhanced on units that operate above 41 bar (595 psi) by
having sets of pressure coefficient constants covering subsets of the full operating pressure range.
Only one set of pressure coefficient constants is selected from your calibration certificate according to
your operating pressure range. If your operating pressure range falls within the range of two sets of
pressure coefficient constants, contact Micro Motion for a new calibration certificate. See Appendix C
for an example calibration certificate.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
Note: If it is required to apply temperature and pressure corrections, the temperature correction is
applied first.
Figure 4-2 shows the typical residual error curves after pressure corrections for 7835 (100Bar) units
using three sets of pressure coefficient constants. Each set covers a sub-set of the 100Bar range. The
uncertainty specification for a 7835 is indicated by the upper and lower limit lines. The uncertainty
for the 7835 pressure coefficients is
uncertainty of
Note: Only one set of pressure coefficient constants is selected from your calibration certificate
according to your operating pressure range. For specimen calibration certificates, see Appendix C.
±0.15 kg/m
3
.
±0.003 kg/m
3
. This is in addition to the instrument calibration
Installation & Configuration Manual 21
Calibration and Performance
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
0 102030405060708090100110
Pressure (BarG)
Magnitude (kg/m3)
New K20 K21
Upper limit
Low er limit
Figure 4-2 Residual pressure effect after pressure correction – 7835 (100Bar) units (at 20°C)
Optimization for pressure-temperature coupling effect (7835 meters only)
For the calibration of 7835 meters, a new generic constant is being applied to calculate the K21A
pressure coefficient that is valid for use over a limited operating temperature and pressure range. The
revised K21A pressure coefficient is selected from a table in a new format calibration certificate and
is unique to the 7835 meter. The application of this K21A coefficient does not change the density
calibration coefficient format or the density calibration equations previously used in the flow
computer software.
Note: This constant can only be applied to 7835 meters that have been calibrated at the factory
beginning in January 2011. Additionally, it is not possible to recalculate a revised K21A for units that
have been recertified at external calibration facilities.
The new constant is being applied as an intermediary measure to meet the requirements of the United
Kingdom Department of Energy and Climate Change (DECC) directive regarding the calibration of
liquid density meters. The DECC directive recommended that by July 2011 all density meters be
calibrated at the anticipated operating conditions (such as simultaneously at temperature and
pressure). Micro Motion is in process of redesigning the calibration stands so that they can operate at
a combined elevated temperature and pressure. These stands are planned to be completed and
operational by July 2011.
For an example of the calibration certificate that includes the new K21A pressure coefficients, see
Appendix C.
22 Micro Motion 7835 Explosion Proof Liquid Density Meters
4.2.4 Velocity of sound correction
The Velocity of Sound (VOS) in the process liquid may have an effect on the accuracy of the
indicated density. The calibration of the 7835 meter has been optimized to a density/VOS relationship
as indicated in Figure 4-3. If the VOS of the process fluid deviates substantially from the relationship
in Figure 4-3, it may be desirable to apply a correction. This may be achieved by the simple
introduction of a calibration offset using the data in Figure 4-3. Adjustment of the value
basic equation will achieve this.
K
0
in the
Calibration and Performance
Alternatively, the following equations may be used:
D
VOS
=
Dp 1
14 06
1400
11
22
+
+
×−
⎛
⎝
⎜
⎞
⎠
⎟
⎡
⎣
⎢
⎤
⎦
⎥
. E
DVV
PCA
Where:
D
VOS
=
(kg/m3)
D
P
= Temperature and pressure cor rected density (kg/m3)
V
C
= Calibration VOS (m/s)
V
A
= Liquid VOS (m/s)
V
C
can be obtained direct from Figure 5.2 or may b e calculated as follows:
V
C
= 100 1455+ . DP for a D
P
of 300kg/m3 to 1100k g/m3
V
C
= 2690 09− . DP for a D
P
of 1100kg/m3 to 1600kg/m3
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2
00
4
00
6
00
800
1
000
120
0
1400
160
0
Indicated Density (kg/m3)
Velocity of Sou n d (m/s)
+2kg/m3
+2kg/m3
Nominal
-2kg/m3
Values shown are the required corrections
True density = Indicated density + Corrections
Vel ocit y of s ou nd and tem perat ure correct ed d ensity
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
Figure 4-3 Optimized velocity of sound relationship for the 7835 Exd meter
Installation & Configuration Manual 23
Calibration and Performance
4.3 Calibration
4.3.1 Factory calibration
The 7835 Explosion Proof Liquid Density meters are calibrated prior to leaving the factory against
Transfer Standard instruments, traceable to National Standards. Three fluids are used in the
calibration – ambient air whose density is derived from look-up tables, hydrocarbon oil of about
815 kg/m
3
density and a high-density fluid in the range 1400 to 1500 kg/m3 density. Several of the
instruments-under-test are connected in parallel between two Transfer Standard Instruments on the
Micro Motion special flow rig. During a calibration, and as the liquid flows through the instruments,
readings are only taken when the indicated densities on the two Transfer Standard Instruments agree.
In this way, a high integrity of calibration is achieved.
Measurements are also made under conditions of changing temperature and pressure to establish the
magnitude of these effects on the instrument. From all this data, a calibration certificate is generated
for each instrument.
Samples of the instruments are further tested by the Micro Motion Quality Assurance Department to
verify the calibration.
4.3.2 Calibration of transfer standards
The Transfer Standard instruments used in the calibration are selected instruments that are calibrated
and certified by the ISO/IEC17025-certified calibration laboratory.
Transfer Standard calibration uses a number of ‘density certified’ liquids. The densities of these
certified liquids are obtained using the Primary measurement system, whereby glass sinkers of
defined volumes are weighed in samples of the liquids.
Calibration is performed by pumping each certified liquid through the Transfer Standard in a closely
controlled manner and recording the output signal in each case. A calibration certificate is issued for
each Transfer Standard.
Calibrations are repeated, typically every six months, producing a well-documented density standard.
4.3.3 Instrument calibration certificate
Each instrument is issued with its own calibration certificate (see Appendix C for samples),
containing four important pieces of data:
• The instrument serial number.
• The output signal/density relationship. This is based on three calibration points – air, medium
density and high-density fluids. The air and high density fluid points are offset to achieve the
product velocity of sound/density profile described earlier. However, the signal value at Air
Density is also given for check purposes.
• Temperature coefficient data, describing the correction which should be applied to achieve the
best accuracy if the instrument is operating at product temperatures other than 20 °C (68 °F).
• Pressure coefficient data, describing the correction that should be applied to achieve the best
accuracy if the instrument is operating at elevated pressures.
A second page of the calibration certificate is retained by Micro Motion and contains all the
calibration measurements.
24 Micro Motion 7835 Explosion Proof Liquid Density Meters
Calibration and Performance
4.3.4 Pressure test
A hydrostatic pressure test is carried out to a pressure value specified on the instrument label and on
the instrument calibration certificate. This test loads the instrument structure to a pressure that
exceeds the maximum permitted operating pressure of the instrument.
Note: During manufacture, the welded structure is pressure tested to conform to the requirements of
EN50018:1997. The outer case is able to withstand 100 bar of internal pressure in the event of
tube/bellows failure.
4.3.5 Insulation test
To comply with Intrinsic Safety requirements, a 500 Vac insulation test is carried out between the
electrical terminals and the instrument case.
4.3.6 Calibration check methods
There are two methods employed in calibration checks:
• Air checkpoint, which is simple and convenient and highlights long term drift, corrosion and
deposition.
• Liquid calibration verification comprising two choices:
- Drawing off a sample of the liquid being measured and obtaining its density, using a
hydrometer (for stable liquids) or pyknometer (for unstable liquids).
- Using a second density meter.
Ambient air check
1. Isolate, drain and if necessary, disconnect the meter from the pipeline.
2. Clean and dry the wetted parts of the meter and leave them open to the ambient air.
3. Apply power to the instrument and check that the time period of the output signal agrees with
the 'Air Check' figure shown in the calibration certificate, to within acceptable limits.
Some variation between the two figures is to be expected due to changes in ambient air
conditions. The density indication if using the K0, K1 and K2 factors will be about –0.9 kg/m
because the basic density equation has been optimized for best performance over the normal
operating density range.
This test will indicate whether there has been a calibration offsets due to corrosion, deposition
or long term drift.
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
3
Temperature
Meter
7835 ±10 ns/°C ±60 ns
correction
Air check limit
at 20 °C
4. Reconnect the meter to the pipeline if serviceable, or remove it for further servicing.
Liquid density check – sample method
If it is necessary to verify the calibration using liquid at operating conditions, then the following
sample methods are recommended:
For Stable Liquids:
Installation & Configuration Manual 25
Calibration and Performance
1. Draw off a sample of the liquid into a suitable container, at the same time noting the indicated
density, temperature and pressure of the liquid.
2. Measure the density of the sample under defined laboratory conditions, using a hydrometer or
other suitable instrument.
3. Refer the density measurement under laboratory conditions to that under the line operating
conditions of temperature and pressure.
4. Compare the referred density figure with that indicated by the density meter.
Note: It is essential that a good understanding of the physical properties (temperature coefficient,
etc.) of the liquid is acquired when using this method.
For Unstable Liquids:
1. Couple a pressure pyknometer and its associated pipework to the pipeline so that a sample of
the liquid flows through it.
2. When equilibrium conditions are reached, the meter density reading is noted as the
pyknometer is isolated from the sample flow.
3. Remove the pyknometer for weighing to establish the product density.
4. Compare the pyknometer registered density with that obtained from the meter.
Sampling Techniques
Sampling should comply with the international sampling standards (ISO 3171, ASTM D 4177, API
8.2 and IP 6.2).
For further details of these procedures, reference should be made to:
Institute of Petroleum: Petroleum Measurement Manual
Part VII Section 1 – Method IP 160 (Hydrometer Method)
(BS2000–160, ISO3675, ASTM 1298)
Institute of Petroleum: Petroleum Measurement Manual
Part VII Section 2 – Continuous Density Measurement
American Petroleum Institute: Manual of Petroleum Measurement Standards
Chapter 14 – Natural Gas Fluids – Section 6:
Installing and proving density meters used to measure
hydrocarbon liquid with densities between 0.3 and 0.7 g/cc at
15.56 °C (60 °F) and saturation vapor pressure, 1991.
Liquid density check – second density meter
It is often the practice, especially in fiscal metering applications, to use two or more density meters in
a continuous measurement mode as a means of improving the integrity of the measurement system.
Any unacceptable discrepancies between the measurements can immediately raise the necessary
alarm signals.
1. Connect the second density meter to the pipeline adjacent to meter being checked so that it
receives the same sample of fluid under the same conditions of temperature and pressure as the
meter under test.
2. Connect the second meter to its readout equipment, switch on and allow both systems to reach
equilibrium conditions.
3. Compare the two readings, making any necessary corrections.
26 Micro Motion 7835 Explosion Proof Liquid Density Meters
Calibration and Performance
This method of automatic checking has proved to be a very successful technique and where there is a
facility for two instruments, the practice of exchanging one for a newly calibrated instrument is
proving successful. This is sometimes referred to as the "Substitution Method".
It is very important when using one instrument to verify the performance of a second and similar
instrument, to ensure there are no unaccounted for systematic errors which would are not highlighted.
4.4 Performance
Micro Motion meters are generally calibrated using specified fluids at 20 °C and 1 bar absolute. When
operating at other conditions, it is necessary to increase the uncertainty of measurement by the
magnitude of the offsets if no corrections are applied or by a fraction of the offsets if corrections are
applied.
The following table lists the sources and magnitudes of the offsets affecting the meters covered in this
manual (including an example below).
Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction Installation Procedure Calibration and PerformanceElectrical Connections (Standard)Introduction
Installation & Configuration Manual 27
Calibration and Performance
22222
GFEDC ++++
Table 4-1. Source and magnitude of measurement offsets
Error source 7835
A Primary Standard 0.05 kg/m
B Transfer Standard 0.1 kg/m
C Instrument Accuracy (at
calibration conditions)
D Temperature (uncorrected)
Temperature (corrected)
E Pressure (uncorr’d at 50 bar)
Pressure (uncorr’d at 100 bar)
Pressure (corrected)
F Velocity of Sound (uncorr’d)
Velocity of Sound (corrected)
G Long term stability 0.15 kg/m
0.15 kg/m
0.02 kg/m3/deg C
0.005 kg/m
–1 to +2 kg/m
+7 to +15 kg/m
0.003 kg/m3/bar
See Section 4.2
20% of offset
3
3
3
3
3
/deg C
3
/year
3
For total operational accuracy, the square root of the sum of the squares of each error source (C to G)
is recommended, such as:
• Effective Total =
For example, if we consider instruments operating at 50 °C (122 °F) and 50 bar, six months after
calibration and with no VOS offset, the total operational accuracy after corrections have been applied
is derived as follows:
Table 4-2. Total operational accuracy for example quoted
Error Source 7835
C
D
E
F
G
Effective Total 0.27
0.15
0.15
0.15
–
0.07
For better accuracy, it would be necessary to carry out an on-line calibration at the operating
conditions. Higher accuracy can be obtained, by request, for all instruments by the use of water
calibration or by UKAS certified laboratory calibration of selected fluids.
Note: The tables above relate to the effect of uncertainties on the time period output of the meter, and
do not take into account any uncertainty in the measurement of the time period itself.
28 Micro Motion 7835 Explosion Proof Liquid Density Meters
Chapter 5
General Maintenance
5.1 General
The 7835 Explosion Proof Liquid Density meters have no moving parts, which reduces the
maintenance requirement to simple visual checks for leaks and physical damage.
Check calibrations should be carried out at specified intervals in order to highlight any malfunction or
deterioration in meter performance. If a fault or a drop in meter performance is discovered, further
tests are required to identify the cause of the fault. Remedial action is limited to cleaning the tube,
making good any poor connections and replacing the maintaining amplifier or, in extreme cases, the
entire instrument.
Extreme care is required in the handling of the meter during transit, its installation into the
pipeline and its removal from the pipeline.
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
5.2 Fault analysis
Faults generally fall into two main categories: erratic readings or readings outside limits.
• Erratic Readings
Normally caused by the presence of gas bubbles in the flowing liquid. Severe electrical
interference or severe pipeline vibrations can also cause this effect.
• Readings Outside Limits
Normally caused by deposition and/or corrosion on the resonating tube.
Since an electrical fault could also cause either of the two faults, and since examination for deposition
or corrosion requires the removal off-line of the meter, it is recommended that the electrical system be
checked first.
5.3 General maintenance procedure
This procedure is recommended for any periodic maintenance carried out on the system and forms the
basis of any faultfinding task.
5.4 Physical checks
Physical checks are as follows:
• Examine the meter and its mounting bracket, pipe couplings and electrical cables for signs of
damage and corrosion.
• Check the meter for signs of fluid leakage and the state of the rupture plate.
Installation & Configuration Manual 29
General Maintenance
Notes:
• Any physical damage to the meter case or mounting brackets may have adverse effects on the
meter performance and a full calibration would be advisable to verify its accuracy.
• Any oil leakage can generally be remedied by servicing.
5.4.1 Check calibration
Checking the calibration is as follows:
• Carry out a check calibration using methods detailed in Chapter 4.
• Compare the results obtained with the current calibration certificate figures to identify any
substantial deterioration in the meter's performance or any malfunction.
Notes:
• A substantial drop in meter performance is likely due to a build-up of deposition on the
vibrating tube, which can be removed by the application of a suitable solvent. See
Section 5.4.2 below.
• Malfunctions may be the result of electrical/electronic faults in either the meter circuit or the
readout equipment. The readout equipment should be proved before attention is directed to the
meter as detailed under Section 5.4.2.
5.4.2 Remedial servicing
The required servicing falls into two categories – electrical and mechanical.
Electrical servicing
1. Follow the steps below.
a. Carry out power supply and current consumption tests at the meter terminals. These
should give: 17 mA
± 1 mA at 15.5 V to 30 V.
b. Remove the power supply to the meter. If current consumption is suspect, replace the
meter amplifier.
c. Identify the drive coils (terminals 7 and 8) and disconnect the drive coil wires from the
amplifier. Measure the resistance of the drive coils. This should be: 95
± 5 ohms at 20 °C
(68 °F).
d. Reconnect the drive coil wires to the amplifier.
2. Identify the pick-up coils (terminals 9 and 10) and disconnect the pick-up coil wires from the
amplifier. Measure the resistance of the pick-up coils. This should be: 95
± 5 ohms at 20 °C
(68 °F).
Reconnect the pick-up coil wires to the amplifier.
3. Follow the steps below.
a. Check the 100 Ω RTD element across the terminals 11 and 12 (ensure terminals 3 to 6 are
disconnected). The value of the element resistance is temperature dependent. For this data,
see the product specifications appendix.
b. Check for continuity between terminals 11 and 3, and terminals 11 and 4, also from
terminals 12 to 5 and 12 to 6.
30 Micro Motion 7835 Explosion Proof Liquid Density Meters
General Maintenance
4. Carry out an insulation test by removing all the input connections to the amplifier terminals
(1 to 7 inclusive) and short-circuit the terminals together. Test their insulation resistance to the
metal case using a 500 V dc insulation tester (current limited to 5 mA maximum). This
resistance must be greater than 2 MΩ.
Remove the short-circuit, and reconnect the input leads if required.
Mechanical servicing
Mechanical servicing comprises mainly of keeping the inner surface of the vibrating tube clear of
deposition and corrosion. Deposition may be removed by the use of a suitable solvent. Alternatively,
the instrument can be removed from the pipeline and cleaned mechanically. Care is required to
prevent damage to the inner surface of the tube during the cleaning.
Great care is essential in handling the meter during transit, installation into the pipeline and
removal from the pipeline.
Ensure that the meter is not transported when it contains hazardous fluids. This includes fluids which
may have leaked into, and are still contained, within the case.
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
Installation & Configuration Manual 31
General Maintenance
32 Micro Motion 7835 Explosion Proof Liquid Density Meters
Appendix A
7835 Explosion Proof (Exd) Specifications
A.1 Density performance
Accuracy
Operating Range
Repeatability
Stability
Process Temperature Effect
(Corrected)
Process Pressure Effect
(Corrected)
(1) Accuracy is dependent upon the calibraton option chosen. Density range for which this accuracy applies depends on the
calibration option chosen.
(2) Stated accuracy is for operating density range of 0.3 to 1.1 g/cc (300 - 1100 kg/m
(3) Temperature effect is the maximum measurement offset due to process fluid temperature changing away from the
density calibration temperature.
(4) Pressure effect is defined as the change in sensor density sensitivity due to process pressure changing away from the
calibration pressure. To determine factory calibration pressure, refer to calibration document shipped with the 7835. If
data is unavailable, contact the factory.
(3)
(4)
±0.0001 g/cc
±0.00015 g/cc
Up to 3 g/cc Up to 3000 kg/m3
±0.00002 g/cc ±0.02 kg/m3
±0.00015 g/cc 0.15 kg/m
±0.000005 g/cc
±0.000278 g/cc
±0.000003 g/cc
±0.000021 g/cc
±0.1 kg/m
±0.15 kg/m
±0.005 kg/m
±0.278 kg/m
±0.003 kg/m
±0.021 kg/m
3
3
3
3
3
3
3
(Enhanced calibration)
(Standard calibration)
(Per year)
(Per °C)
(Per 100
°F)
(Per bar)
(Per 100 psi)
3
).
(1)
(2)
A.2 Temperature specifications
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
Operating Range –50 °C to +110 °C (–58 °F to +230 °F)
Integral temperature sensor:
Technology 100 Ohms RTD (4 wire)
Accuracy BS 1904 Class, DIN 43760 Class A.
Installation & Configuration Manual 33
7835 Explosion Proof (Exd) Specifications
A.3 Pressure ratings
Maximum operating
pressure
Test pressure Tested to 1.5 times the maximum operating pressure
PED compliance Complies with European directive 97/23/EC on Pressure Equipment.
Explosion proof (Exd) 1450 psi (100 bar)
A.4 Hazardous area classifications
ATEX Explosion Proof
ATEX-approved Exd 7835: Certification for use in Europe
7835 (Frequency Output): (7835****AK****) ATEX II2G EEx d IIC
T6 (Ta –40 °C...+70 °C)
CSA Explosion Proof
CSA-approved Exd 7835: Certification for use in Canada and USA
7835 (Frequency Output): (7835****AM****) Class I, Division 1 Groups C & D, T3C
A.5 OIML R117-1 classifications
Evaluation to OIML R117-1 Edition 2007 (E) and Measuring Instrument Directive (2004/22/EC) Annex MI-005
Viscosity range 0.75 cP to 50 cP (0.75 mPa
Density range 0.7 g/cc to 1.2 g/cc (700 kg/m
Temperature range ambient –40
Environmental class Mechanical: M2
Maximum pressure Fluid temperature range Accuracy Class
• 928.2 psi (64 bar) • +23 °F to +131 °F (–5 °C to +55 °C) • 0.3
• 1450.4 psi (100 bar) • +32
• 1450.4 psi (100 bar) • +23 °F to +131 °F (–5 °C to +55 °C) • 1.0
°F to +158 °F (–40 °C to +70 °C)
Electromagnetic: E2
°F to +104 °F (0 °C to 40 °C) • 0.3
·s to 50 mPa·s)
3
to 1200 kg/m3)
A.6 Electromagnetic compatibility
All versions conform to the latest international standards for EMC, and are compliant with
EN 61326/IEC 61326.
34 Micro Motion 7835 Explosion Proof Liquid Density Meters
7835 Explosion Proof (Exd) Specifications
A.7 Materials of construction
Wetted parts Ni-Span-C® and 316L Stainless steel
Case finish 316L Stainless steel
Flange 316L Stainless steel
A.8 Weight
Weight Explosion proof (Exd) 77 lb (35 kg)
A.9 Electrical
Power supply (Standard version) 16 to 28 VDC at 17 mA maximum
Outputs (Standard version) Current modulation on power supply line
A.10 Safety approval
See the ATEX or CSA Safety Instructions booklet for explosion proof liquid density meters for safety
approval information. The booklet was shipped with the product or is available at
www.micromotion.com.
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
Installation & Configuration Manual 35
36 Micro Motion 7835 Explosion Proof Liquid Density Meters
Appendix B
Electronics Specifications
B.1 Standard Electronics
B.1.1 Meter Power Supply
Safe Areas: +16 V to +28 Vdc
Hazardous Areas: +24 V (nominal)
Minimum Input Voltage: > 15.5 Vdc
B.1.2 Output Signals
Output Signals: 2 wire
2 V across 180
4 V across 390 Ω
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
Ω
B.2 Environmental Performance
B.2.1 Temperature
Standard Electronics
Operating: –40 to +85 °C (–40 to +185 °F)
B.2.2 IP rating
Standard electronics enclosure: IP66
Storage: –40 to +85 °C (–40 to +185 °F)
Installation & Configuration Manual 37
Electronics Specifications
38 Micro Motion 7835 Explosion Proof Liquid Density Meters
Appendix C
Calibration Certificates
C.1 Example calibration certificates
The following certificates are examples of the calibration certificate for the liquid density meters.
None of these are the calibration certificates for your product. The calibration certificate for your
product is shipped with the unit.
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
Installation & Configuration Manual 39
Calibration Certificates
CALIBRATION CERTIFICATE
Temperature-Pressure Coupling
(Generic Constant)
Page 1 of 2
7835B LIQUID DENSITY METER Serial No : 356283
7835BAAFAJTAAX Cal. Date : 30SEP10
Pressure Test :151BarA
DENSITY CALIBRATION AT 20°C AND AT 1 BarA
DENSITY PERIODIC TIME
[KG/M3] [uS]
0 1086.354 DENSITY = K0 + K1.T + K2.T**2
(Air 1085.965)
300 1206.303 K0 = -1.13597E+03 \
600 1314.344 K1 = -2.62138E-01 } 300 - 1100 kg/m3
800 1381.273 K2 = 1.20451E-03 /
900 1413.447
1000 1444.844
1100 1475.519 K0 = -1.13262E+03 \
1200 1505.519 K1 = -2.70949E-01 } 0 - 3000 kg/m3
1600 1619.559 K2 = 1.20908E-03 /
TEMPERATURE COEFFICIENT DATA
Dt=D(1+K18(t-20))+K19(t-20) K18 = -1.83580E-05
K19 = 1.50424E-02
PRESSURE COEFFICIENT DATA
DP=Dt(1+K20(P-1))+K21(P-1) K20 = K20A + K20B(P-1)
K21 = K21A + K21B(P-1)
RANGE ( <41 BarA) RANGE (31-71 BarA)
K20A = -1.93584E-04 K20A = -1.75547E-04
K20B = 8.48471E-07 K20B = 3.33109E-07
K21A = See page 2 K21A = See page 2
K21B = -4.14579E-03 K21B = -3.26551E-03
RANGE (61-101 BarA)
K20A = -1.39003E-04
K20B = -2.29104E-07
K21A = See page 2
K21B = -2.30520E-03
where D = Density ( Uncorrected )
Dt = Density ( Temperature Corrected )
DP = Density ( Temperature-Pressure Corrected )
T = Periodic Time ( uS )
t = Temperature ( °C )
P = Pressure (BarA)
Figure C-1 Example of a calibration certificate with pressure-temperature coupling optimization
(page 1 of 2)
example
example
40 Micro Motion 7835 Explosion Proof Liquid Density Meters
Calibration Certificates
CALIBRATION CERTIFICATE
Temperature-Pressure Coupling
(Generic Constant)
Page 2 of 2
TEMPERATURE-PRESSURE COUPLING COEFFICIENT DATA
Table 1 : K21A(Coupled) at operation temperature
+-----------------------------------------------------------+
| Temp |K21A| |
| Range | @ | Pressure Range |
+---------+----+--------------+--------------+--------------+
| LO | HI | | | | |
| °C | °C | °C | <41 BarA | 31-71 BarA | 61-101 BarA |
+---------+----+--------------+--------------+--------------+
|-50 |-40 |-45 | 3.14842E-01 | 2.83321E-01 | 2.19462E-01 |
|-45 |-35 |-40 | 3.14296E-01 | 2.82830E-01 | 2.19081E-01 |
|-40 |-30 |-35 | 3.13750E-01 | 2.82339E-01 | 2.18701E-01 |
|-35 |-25 |-30 | 3.13204E-01 | 2.81847E-01 | 2.18320E-01 |
|-30 |-20 |-25 | 3.12658E-01 | 2.81356E-01 | 2.17939E-01 |
+---------+----+--------------+--------------+--------------+
|-25 |-15 |-20 | 3.12112E-01 | 2.80865E-01 | 2.17559E-01 |
|-20 |-10 |-15 | 3.11566E-01 | 2.80373E-01 | 2.17178E-01 |
|-15 | -5 |-10 | 3.11020E-01 | 2.79882E-01 | 2.16798E-01 |
|-10 | 0 | -5 | 3.10474E-01 | 2.79391E-01 | 2.16417E-01 |
| -5 | 5 | 0 | 3.09928E-01 | 2.78899E-01 | 2.16036E-01 |
+---------+----+--------------+--------------+--------------+
| 0 | 10 | 5 | 3.09382E-01 | 2.78408E-01 | 2.15656E-01 |
| 5 | 15 | 10 | 3.08836E-01 | 2.77917E-01 | 2.15275E-01 |
| 10 | 20 | 15 | 3.08290E-01 | 2.77425E-01 | 2.14895E-01 |
| 15 | 25 | 20 | 3.07744E-01 | 2.76934E-01 | 2.14514E-01 |
| 20 | 30 | 25 | 3.07198E-01 | 2.76443E-01 | 2.14134E-01 |
+---------+----+--------------+--------------+--------------+
| 25 | 35 | 30 | 3.06652E-01 | 2.75951E-01 | 2.13753E-01 |
| 30 | 40 | 35 | 3.06106E-01 | 2.75460E-01 | 2.13372E-01 |
| 35 | 45 | 40 | 3.05560E-01 | 2.74969E-01 | 2.12992E-01 |
| 40 | 50 | 45 | 3.05014E-01 | 2.74477E-01 | 2.12611E-01 |
| 45 | 55 | 50 | 3.04468E-01 | 2.73986E-01 | 2.12231E-01 |
+---------+----+--------------+--------------+--------------+
| 50 | 60 | 55 | 3.03922E-01 | 2.73495E-01 | 2.11850E-01 |
| 55 | 65 | 60 | 3.03376E-01 | 2.73004E-01 | 2.11470E-01 |
| 60 | 70 | 65 | 3.02830E-01 | 2.72512E-01 | 2.11089E-01 |
| 65 | 75 | 70 | 3.02284E-01 | 2.72021E-01 | 2.10708E-01 |
| 70 | 80 | 75 | 3.01738E-01 | 2.71530E-01 | 2.10328E-01 |
+---------+----+--------------+--------------+--------------+
| 75 | 85 | 80 | 3.01192E-01 | 2.71038E-01 | 2.09947E-01 |
| 80 | 90 | 85 | 3.00646E-01 | 2.70547E-01 | 2.09567E-01 |
| 85 | 95 | 90 | 3.00100E-01 | 2.70056E-01 | 2.09186E-01 |
| 90 |100 | 95 | 2.99554E-01 | 2.69564E-01 | 2.08806E-01 |
| 95 |105 |100 | 2.99008E-01 | 2.69073E-01 | 2.08425E-01 |
|100 |110 |105 | 2.98462E-01 | 2.68582E-01 | 2.08044E-01 |
+---------+----+--------------+--------------+--------------+
--------------
| FINAL TEST & |
| INSPECTION |
| |
| |
| |
------------- Ref No:- LD7835/V6.09T/FVB DATE : 30SEP10
Figure C-2 Example of a calibration certificate with pressure-temperature coupling optimization
(page 2of 2)
example
example
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance 7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance 7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance 7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
Installation & Configuration Manual 41
Calibration Certificates
Figure C-3 Example of certificate with 3 sets of pressure coefficients (Metric Units)
7835B LIQUID DENSITY METER Serial No : 356366
7835BAAFAJTAAA Cal. Date : 14MAR07
Pressure Test : 151 BARA
DENSITY CALIBRATION AT 20 DEG. C AND AT 1 BARA
DENSITY PERIODIC TIME
[KG/M3] [uS]
0 1086.919 DENSITY = K0 + K1.T + K2.T**2
(Air 1086.520)
300 1209.943 K0 = -1.10786E+03 \
600 1320.514 K1 = -2.52754E-01 } 300 - 1100 kg/m3
800 1388.922 K2 = 1.17101E-03 /
900 1421.788
1000 1453.850
1100 1485.163 K0 = -1.10439E+03 \
1200 1515.779 K1 = -2.61778E-01 } 0 - 3000 Kg/m3
1600 1632.089 K2 = 1.17566E-03 /
TEMPERATURE COEFFICIENT DATA
CALIBRATION CERTIFICATE
Dt=D(1+K18(t-20))+K19(t-20) K18 = -1.80459E-05
K19 = 1.51725E-02
PRESSURE COEFFICIENT DATA
DP=Dt(1+K20(P-1))+K21(P-1) K20 = K20A + K20B(P-1)
K21 = K21A + K21B(P-1)
RANGE ( <41 BARA) RANGE (31-71 BARA)
K20A = 1.02046E-05 K20A = 5.64682E-06
K20B = -1.38764E-06 K20B = -1.25741E-06
K21A = 1.70570E-01 K21A = 1.55537E-01
K21B = -2.75303E-03 K21B = -2.32351E-03
RANGE (61-101 BARA)
K20A = -3.58705E-06
K20B = -1.11536E-06
K21A = 1.25081E-01
K21B = -1.85495E-03
where D = Density ( Uncorrected )
Dt = Density ( Temp Corrected )
DP = Density ( Pressure Corrected )
T = Periodic Time ( uS )
t = Temperature ( DEG.C )
P = Pressure (BarA)
------------- | FINAL TEST & |
| INSPECTION |
| |
| |
| |
------------- Ref No:- LD7835/V5.0/FVA DATE : 17MAR07
42 Micro Motion 7835 Explosion Proof Liquid Density Meters
Calibration Certificates
Figure C-4 Example of certificate with 3 sets of pressure coefficients (US Units)
7835B LIQUID DENSITY METER Serial No : 356366
7835BAAFAJTAAA Cal. Date : 14MAR07
Pressure Test : 2175 PSIG
DENSITY CALIBRATION AT 68 DEG. F AND AT 0 PSIG
DENSITY PERIODIC TIME
[ g/cc] [uS]
0.000 1086.919 DENSITY = K0 + K1.T + K2.T**2
(Air 1086.520)
0.300 1209.943 K0 = -1.10786E+00 \
0.600 1320.514 K1 = -2.52754E-04 } 0.300 - 1.100 g/cc
0.800 1388.922 K2 = 1.17101E-06 /
0.900 1421.788
1.000 1453.850
1.100 1485.163 K0 = -1.10439E+00 \
1.200 1515.779 K1 = -2.61778E-04 } 0.000 - 3.000 g/cc
1.600 1632.089 K2 = 1.17566E-06 /
TEMPERATURE COEFFICIENT DATA
CALIBRATION CERTIFICATE
7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance 7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance 7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance 7835 Exd Specifications Calilbration CertificatesElectronics SpecificationsMaintenance
Dt=D(1+K18(t-68))+K19(t-68) K18 = -1.00255E-05
K19 = 8.42918E-06
PRESSURE COEFFICIENT DATA
DP=Dt(1+K20(P))+K21(P) K20 = K20A + K20B(P)
K21 = K21A + K21B(P)
RANGE ( <580 PSIG) RANGE (435-1015 PSIG)
K20A = 7.03762E-07 K20A = 3.89436E-07
K20B = -6.59993E-09 K20B = -5.98057E-09
K21A = 1.17635E-05 K21A = 1.07267E-05
K21B = -1.30941E-08 K21B = -1.10512E-08
RANGE (870-1450 PSIG)
K20A = -2.47383E-07
K20B = -5.30490E-09
K21A = 8.62626E-06
K21B = -8.82260E-09
where D = Density ( Uncorrected )
Dt = Density ( Temp Corrected )
DP = Density ( Pressure Corrected )
T = Periodic Time ( uS )
t = Temperature ( DEG.F )
P = Pressure (PSIG)
------------- | FINAL TEST & |
| INSPECTION |
| |
| |
| |
------------- Ref No:- LD7835/V5.0/FVA DATE : 17MAR07
Installation & Configuration Manual 43
Calibration Certificates
44 Micro Motion 7835 Explosion Proof Liquid Density Meters
Appendix D
Return Policy
D.1 General guidelines
Micro Motion procedures must be followed when returning equipment. These procedures ensure legal
compliance with government transportation agencies and help provide a safe working environment for
Micro Motion employees. Failure to follow Micro Motion procedures will result in your equipment
being refused delivery.
Information on return procedures and forms is available on our web support system at
www.micromotion.com, or by phoning the Micro Motion Customer Service department.
D.2 New and unused equipment
Only equipment that has not been removed from the original shipping package will be considered new
and unused. New and unused equipment requires a completed Return Materials Authorization form.
Return Policy
D.3 Used equipment
All equipment that is not classified as new and unused is considered used. This equipment must be
completely decontaminated and cleaned before being returned.
Used equipment must be accompanied by a completed Return Materials Authorization form and a
Decontamination Statement for all process fluids that have been in contact with the equipment. If a
Decontamination Statement cannot be completed (for example, for food-grade process fluids), you
must include a statement certifying decontamination and documenting all foreign substances that have
come in contact with the equipment.
Installation & Configuration Manual 45
Return Policy
46 Micro Motion 7835 Explosion Proof Liquid Density Meters
Micro Motion Inc. USA
Worldwide Headquarters
7070 Winchester Circle
Boulder, Colorado 80301
T +1 303-527-5200
+1 800-522-6277
F +1 303-530-8459
Micro Motion Europe
Emerson Process Management
Neonstraat 1
6718 WX Ede
The Netherlands
T +31 (0) 318 495 555
F +31 (0) 318 495 556
Micro Motion Japan
Emerson Process Management
1-2-5, Higashi Shinagawa
Shinagawa-ku
Tokyo 140-0002 Japan
T +81 3 5769 -6803
F +81 3 5769-6844
Micro Motion Asia
Emerson Process Management
1 Pandan Crescent
Singapore 128461
Republic of Singapore
T +65 6777-8211
F +65 6770-8003
Micro Motion United Kingdom
Emerson Process Management Limited
Horsfield Way
Bredbury Industrial Estate
Stockport SK6 2SU U.K.
T +44 0870 240 1978
F +44 0800 966 181
©2011, Micro Motion, Inc. All rights reserved. P/N MMI-20015053, Rev. AC
*MMI-20015053*
For the latest Micro Motion product specifications, view the
PRODUCTS section of our web site at www.micromotion.com
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