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.
Handle the 7827 digital viscosity meter with great care.
•Do not drop the meter.
•Do not use liquids incompatible with materials of construction.
•Do not operate the meter above its rated pressure or maximum temperature.
•Do not pressure test beyond the specified test pressure.
•Ensure all explosion-proof requirements have been applied.
•Ensure the meter and associated pipework are pressure tested to 1-1/2 times the maximum
operating pressure after installation.
•Always store and transport the meter in its original packaging, including the transit cover
secured by grub screws.
•To return a meter, refer to the Return Policy appendix 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.
The 7827 meter is a digital viscosity meter, based on the proven tuning fork technology of Micro
Motion. It is an all-welded sensor designed to be mounted directly into a pipeline or in a tank.
Viscosity and density are determined from the resonance of the tuning fork immersed in the fluid, and
a temperature sensor (PRT) is also fitted within the meter.
The 7827 meter is available in a variety of materials, and the immersed tines can be laminated with
PFA to inhibit the build up of residues such as asphaltenes.
1.2.27827 meter measurements
The 7827 meter directly measures the following fluid properties:
•Line dynamic viscosity – measured in centiPoise - cP.
•Line Density – measured in kg/m
3
.
•Temperature – measured in °C or °F.
From these properties, the 7827 meter calculates:
•Line and base (referred) kinematic viscosity – measured in centiStokes - cSt.
•Line and base (referred) density – API or Matrix.
•Referral is made to 15°C, 1.013 bar; or at 60°F, 14.5 psi.
2Micro Motion 7827 Digital Viscosity Meter
Introduction
0dB level
-3dB level
Frequency
τ
B
τ
A
A
B
1.2.3What is it used for?
The 7827 meter is ideally suited to applications where continuous real time measurement of viscosity
is required. The meter is particularly suited where viscosity is an indication of the behavioral
properties of the fluid, for example in applications involving spraying, coating or dipping.
Some uses are in the oil and petrochemical industry for:
•Refining
•Marine
•Power
•Heavy fuel oil (HFO) blending and bunkering
1.3Principle of operation
The 7827 meter operates on the vibrating element principle, the element in this case being a slender
tuning fork structure which is immersed in the liquid being measured.
The tuning fork is excited into oscillation by a piezo-electric crystal internally secured at the root of
one tine, while the frequency of oscillation is detected by a second piezo-electric crystal secured at the
root of the other tine. The sensor is maintained at its first natural resonant frequency, as modified by
the surrounding fluid, by an amplifier circuit located in the electronics housing.
The electronics circuit actually excites the sensor into oscillation alternately at two positions on the
frequency response curve as shown in Figure 1-1. In doing this, the quality factor (Q) of the resonator
may be determined as well as the resonant frequency.
For details of the viscosity and density calculations, see the Calculated Parameters appendix.
Figure 1-1Frequency response curve showing the quality factor (Q) calculation
Response
Installation and Configuration Manual3
Introduction
4Micro Motion 7827 Digital Viscosity Meter
Chapter 2
Installation (Short Stem)
For information on installing a long-stem version of the 7827 digital viscosity meter, see Chapter 3.
2.1Introduction
All drawings and dimensions given in this manual are given here for planning purposes only. Before
commencing fabrication, reference should always be made to the current issue of the appropriate
drawings. Contact Micro Motion for details.
For further information on handling and using the meter, see “Safety guidelines” on page 1
There are a variety of external factors that affect the ability of the 7827 digital viscosity meter to
operate successfully. In order to ensure that your system works correctly, the effects of these factors
must be taken into consideration when designing your installation.
There are two main aspects to consider:
•The accuracy and repeatability of the measurements
•The relevance of the measurements to the overall purpose of the system
Factors which may adversely affect accuracy and repeatability include:
•The presence of gas or bubbles within the fluid being measured
•Non-uniformity of the fluid
•The presence of solids as contaminants
•Fouling of the meter
•Temperature gradients
•Cavitations and swirls
•Operating at temperatures below the wax point of crude oils
•The correct pipe diameter that corresponds to the calibration of the meter.
In some applications, absolute accuracy is less important than repeatability. For example, in a system
where the control parameters are initially adjusted for optimum performance, and thereafter only
checked periodically.
The term achievable accuracy can be used to describe a measure of the product quality that can be
realistically obtained from a process system. It is a function of measurement accuracy, stability and
system response. High accuracy alone is no guarantee of good product quality if the response time of
the system is measured in tens of minutes, or if the measurement bears little relevance to the operation
of the system. Similarly, systems which require constant calibration and maintenance cannot achieve
good achievable accuracy.
Installation and Configuration Manual5
Installation (Short Stem)
long axis
short
axis
Factors which may adversely affect the relevance of the measurements could include:
•Measurement used for control purposes being made too far away from the point of control, so
that the system cannot respond properly to changes.
•Measurements made on fluid which is unrepresentative of the main flow.
2.2Boundary effects
Any insertion device or meter can only measure the properties of the fluid within the region of fluid to
which it is sensitive.
For practical reasons, it is helpful to consider the sensitive, or effective region, for the viscometer as
an ovoid centered on the tips of the tines with its long axis aligned with the direction in which the
tines vibrate, as shown below. The 7827 meter is insensitive to the properties of the fluid outside this
region and progressively more sensitive to fluid properties the closer the fluid is to the tines. Density
can be considered a “mass centered” effect and viscosity a “surface centered” effect in this
visualization; i.e. the measurement of density is more uniformly sensitive to the density of fluid
throughout the region while viscosity measurement is much more critically sensitive to fluid on the
surface of the tines.
If part of this volume is taken up by the pipework or fittings there is said to be a boundary effect; i.e.,
the intrusion of the pipe walls will alter the calibration. The diagram below illustrates the 7827 meter
installed in a pocket on the side of a 4" (100 mm) horizontal pipe line (viewed from above). The
effective region is completely enclosed within the pipe line and thus is completely fluid.
6Micro Motion 7827 Digital Viscosity Meter
Installation (Short Stem)
Top or Plan view
4” horizontal pipe
2”Schedule 40
Pocket or “T”
This next view shows other pipe outlines superimposed:
The smaller circle represents a 4" (100 mm) vertical pipe, which because the 7827 meter orientation is
constant irrespective of pipe orientation intersects the effective region. The 6" (150 mm) pipe is the
smallest pipe diameter to completely enclose the effective region when the pipe is vertical. Thus
smaller pipe diameters can lead to a variety of different geometries which would each require a
separate calibration.
An alternative condition is shown in the next diagram where the side pocket is extended until it passes
completely through the effective region producing a “core”:
Installation (Short Stem)
From this, it would appear that almost every installation requires a separate in situ calibration – a very
undesirable situation. The problem is resolved by providing standard calibration geometries which
can be used in all pipe work configurations and thereby allow the factory calibration conditions to be
reproduced in the process.
2.3Standard installations
2.3.1Overview
To overcome the need for in situ calibration for every installation, three standard installations are
proposed. If an installation conforms to one of these standards, the factory calibration of the 7827
meter is valid, and in-situ calibration unnecessary. Table 2-1summarizes the three installations. For
tank installations, consult Micro Motion.
Approval for use in hazardous areas is limited to –40 to +200°C (–40 to +392°F)
2.3.2Meter orientation
The meter must always be installed horizontally, and orientated to allow flow in the gap between the
tines. This is irrespective of the pipe line orientation, and helps to prevent the trapping of bubbles or
solids on the meter.
Installation and Configuration Manual9
Installation (Short Stem)
Bubbles rise!
Solids sink!
the slot
must be
vertical
.
For ALL pipe and flow directions
.
the meter
must be
horizontal
Figure 2-1Meter orientation
Note: All drawings and dimensions given in the following sections are derived from detailed
dimensional drawings. They are given here for planning purposes only. Before commencing
fabrication, reference should always be made to the current issue of the appropriate drawings contact Micro Motion for details.
2.3.3Free stream installation - flanged fitting
Conditions:
•Flow: 0.3 to 0.5 m/s (at the meter)
•Viscosity: 0.5 to 12,500 cP
•Temperature: -50 °C to 200 °C (–58 °F to 392 °F)
[-40 °C to 200 °C (-40 °F to 392 °F) in hazardous areas]
Note: The thermal mass of the flanges may affect the response time of the meter to temperature
changes.
The view shown below is schematic to show the dimensions of the side pocket, which is fabricated by
the end user.
The pocket geometry must be consistent with 2" schedule 40 tube in both internal diameter and
minimum wall thickness, such as:
•Internal diameter: 2" (52.5 mm)
•Wall thickness: minimum 0.15" (3.912 mm)
Weld neck or slip-on flanges may be used, according to the flange rating selected. However, for
higher rated flanges, only slip-on flanges may give the necessary clearances.
2.3.4Free stream installation - weldolet
This is the preferred option where temperature variations are a critical factor. The reduced thermal
mass of the weldolet's taper-lock fitting renders it more able to track rapid changes in temperature.
Conditions:
•Flow: 0.3 to 0.5 m/s (at the meter)
•Viscosity: 0.5 to 12,500 cP
•Temperature: -50 °C to 200 °C (–58 °F to 392 °F)
[-40 °C to 200 °C (-40 °F to 392 °F) in hazardous areas]
The weldolet has a 1.5" taper lock fitting, and is supplied to be welded on 4", 6", 8" or 10" pipelines.
Use of the weldolet ensures that the tines of the 7827 meter are orientated correctly and are fully
inserted into the fluid stream.
Before fitting the weldolet, the pipeline must be bored through at 2.1" (52.5 mm) diameter to accept
the viscometer. The weldolet must be welded to the pipeline concentrically with the pre-bored hole.
The view shown below is a schematic to show the relevant dimensions.
Installation and Configuration Manual11
Installation (Short Stem)
10” (254 mm)
Horizontal: 4” or larger
Vertical: 6” or larger
Weld
4.4” (111 mm)
Free stream weldolet
to suit pipe diameter
(4, 6, 8 or 10” N.B.)
2.1” (52.5 mm)
min
Figure 2-2Free stream 1.5" Swagelock fitting
The installation will conform generally to Schedule 40 pressure ratings. The weldolet fabrication is
rated to 100 Bar at ambient temperature.
Note: Correct installation and pressure testing of the fitting is the responsibility of the user.
2.3.5T-piece installation
Conditions:
The thermal mass of the flanges may affect the response time of the meter to temperature changes.
Flow velocity at the pipe wall and fluid viscosity must be within the limits shown to ensure that the
fluid within the pocket is refreshed in a timely manner. This installation will not respond as rapidly as
the free-stream installation to step changes in viscosity.
The view shown is a schematic to show the dimensions of the side pocket, which is fabricated by the
end user.
•Flow: 0.5 to 3.0 m/s (at the pipe wall)
•Viscosity: 0.5 to 100 cP
•Temperature: -50 °C to 200 °C (–58 °F to 392 °F)
[-40 °C to 200 °C (-40 °F to 392 °F) in hazardous areas]
The pocket geometry must be consistent with 2" schedule 40 tube in both internal diameter and
minimum wall thickness, i.e.:
•Internal diameter: 2.1" (52.5 mm)
•Wall thickness : minimum 0.15" (3.912 mm)
Weld neck or slip-on flanges may be used, according to the flange rating selected. However, for
higher rated flanges, only slip-on flanges may give the necessary clearances.
2.3.6Flow-through chamber installation
Flow-through chambers are fabricated by Micro Motion, and are available with either weld prepared
ends or with flange or compression fittings for connection into the process pipe lines. They are
available with 1" NB, 2" NB, or 3" NB inlet and outlet pipes.
Note: The length of the inlet and outlet pipes must not be altered, otherwise the temperature response
and stability of the fitting may be adversely affected.
Conditions:
•Flow: constant, between 10 and 30 l/min for 2" sch 40 calibration bore section, 5–300 l/min
for 3" sch 80 calibration bore.
•Viscosity: 0.5 to 1000 cP
•Temperature: -50 °C to 200 °C (–58 °F to 392 °F)
[-40 °C to 200 °C (-40 °F to 392 °F) in hazardous areas]
Installation and Configuration Manual13
•Pressure: 70 bar @ 204 °C, subject to process connections.
The PT100 is a direct insertion type, without a thermowell, and uses a ¾" Swagelok connection.
The diagram below shows an example of this type of standard installation.
Installation (Short Stem)
Dimensions shown in inches (mm)
The three compression fittings on the flow pockets (½" drain, ¾" temp probe, and 1-½" mounting nut
for the meter) are rated to above the working pressure of the flow pocket. The fittings may be
Swagelok or Parker; both are used in manufacture.
The fittings are certified to the following standards:
•Swagelok: SO9001 / 9002, ASME,TUV,CSA,DNV
•Parker: ISO 9001 / 9002, TUV, DNV, LLOYDS
2.4Installation in the pipeline or system
Viscosity is a highly sensitive indicator of change in a fluid – a key reason why viscosity
measurement is increasingly being chosen as a process measurement.
This sensitivity means that the measurement can be very sensitive to extraneous effects and therefore
great care must be taken to consider all the factors which affect measurement when assessing the
installation requirements.
Like many other meters, the optimum performance of the viscometer depends upon certain conditions
of the fluid and configuration of the process pipe-work. By introducing appropriate flow conditioning,
the optimum performance of the 7827 meter can be achieved at any chosen location in the process
system.
14Micro Motion 7827 Digital Viscosity Meter
Installation (Short Stem)
You must first select a location which serves the application objective; e.g. installed close to the point
of control. Then, consideration can be given to fluid conditioning at that point. Where the application
requirements allow a degree of tolerance in the point chosen for installation, the installation may be
able to take advantage of natural flow conditioning.
The choice of mechanical installation (free stream, “T” piece or flow-through chamber) will be
dictated partly by application needs and partly by the fluid conditions, such as:
•Condition of fluid at the sensor
•Thermal effects
•Flow rate
•Entrained gas
•Solids contamination
Fluid at the sensor
The fluid in the effective zone of the 7827 meter must be of uniform composition and at uniform
temperature. It must be representative of the fluid flow as a whole.
This is achieved either by mixing of the fluid either using a static inline mixer or taking advantage of
any natural pipe condition that tends to cause mixing, such as pump discharge, partially open valves.
The viscometer should be installed downstream where the flow is just returning to laminar flow
conditions.
Thermal effects
Avoid temperature gradients in the fluid and in the pipe work and fittings immediately upstream and
downstream of the viscometer.
Always insulate the viscometer and surrounding pipework thoroughly. Insulation must be at least
1" (25 mm) of rockwool, preferably 2" (50 mm) (or equivalent insulating heat jacket) and enclosed in
a sealed protective casing to prevent moisture ingress, air circulation, and crushing of the insulation.
Special insulation jackets are available from Micro Motion for the flow-through chambers, which,
because of the low volumetric flow rates and hence low heat flow, are more vulnerable to temperature
effects.
Avoid direct heating or cooling of the viscometer and associated pipe work upstream and downstream
that is likely to create temperature gradients. If it is necessary to provide protection against cooling
due to loss of flow, electrical trace heating may be applied, provided it is thermostatically controlled
and the thermostat is set to operate below the minimum operating temperature of the system.
Where flow-through chambers are used and where base (or referred) viscosity is required and the
behavior of the fluid is such that the temperature of the sample flow will require controlling, heat
exchangers should be fitted upstream a sufficient distance from the chamber so that the fluid
temperature is relatively stable. Insulation should be extended from the viscometer to the outlet from
the heat exchanger. Fluid heat exchangers should be controlled by modulating the flow rate of the heat
exchange fluid and not by modulating the sample flow rate.
Flow rate
Flow rates and velocities should be maintained relatively constant within the limits given. The fluid
flow provides a steady heat flow into the viscometer section, and the flow rate influences the self
cleaning of the sensor and the dissipation of bubbles and solid contaminants.
Installation and Configuration Manual15
Installation (Short Stem)
Where it is necessary to install the viscometer in a by-pass (either using the free stream installation in
a 4" diameter horizontal by-pass, or a flow-through chamber), flow may be maintained using pressure
drop, pitot scoop, or by a sample pump. Where a pump is used, the pump should be upstream of the
viscometer.
Entrained gas
Gas pockets can disrupt the measurement. A brief disruption in the signal caused by transient gas
pockets can be negated in the signal conditioning software, but more frequent disruptions or serious
gas entrainment must be avoided. This can be achieved by observing the following conditions:
•Keep pipe lines fully flooded at all times
•Vent any gas prior to the viscometer
•Avoid sudden pressure drops or temperature changes which may cause dissolved gases to
break out of the fluid
•Maintain a back pressure on the system sufficient to prevent gas break out (e.g. back pressure
equivalent to twice the ‘head loss’ plus twice the vapor pressure)
•Maintain flow velocity at the sensor within the specified limits.
Solids contamination
•Avoid sudden changes of velocity that may cause sedimentation.
•Install the viscometer far enough downstream from any pipework configuration which may
cause centrifuging of solids (e.g. bends).
•Maintain flow velocity at the sensor within the specified limits.
•Use filtration if necessary.
The diagram below illustrates some of the principles outlined in this section. It shows a free-stream
viscometer installation with an additional sample take off. The position of both is such that the static
mixing (which could be caused by pump discharge or partially closed valve), has negated the adverse
effects of bends and established laminar flow, and has ensured that the fluid is thoroughly mixed and
thus of uniform composition and temperature. The ideal place for a free stream or “T” piece
installation, or for the by-pass take off point is where the flow has just begun to be laminar.
Note: The insulation extends upstream and downstream far enough to prevent conduction losses in the
pipe walls from degrading the temperature conditioning of the fluid at the sensor.
The following diagrams illustrate some typical solutions for line viscosity measurement, simple base
viscosity referral and base viscosity using temperature control of the sample flow.
In all examples, the fluid flow is assumed to be uniform in composition and temperature as it enters
the viscometer section.
2.5.1Jacketed pipeline
The diagram below shows a jacketed pipeline. The heating fluid in the jacket will cause temperature
gradients, and therefore it is discontinued through the viscometer section. If protection against cooling
due to loss of flow is required through the unjacketed section then it must be provided using electrical
trace heating.
Installation and Configuration Manual17
Installation (Short Stem)
Figure 2-3Jacketed pipeline installation
Alternatively, the viscometer can be installed in a by-pass. By ensuring that the sample is mixed
where the by-pass draws off the main pipeline, it is not necessary to discontinue the main pipe line
jacket. This is shown below.
Figure 2-44" bypass using DP to generate constant flow at the meter
18Micro Motion 7827 Digital Viscosity Meter
Installation (Short Stem)
PT10 0
(optional)
Pump
10-30 l/min
Insulation
(required)
Optional drain line (½”)
either vented or
returned to process
Line or Base Viscosity: temperature not conditioned
Horizontal Pipe line
Flowmeter
(optional)
1”-2” sample lines
Always install the chamber with flow
in horizontal and flow out vertically
upwards.
Drain, to purge solids, is vertically
down and can be vented and/or
returned to line.
Side Wall Tappin g
Side Wall Tapping
with Pitot Scoop
Meter in 2”
flow-through
chamber
2.5.2Flow-through chamber
The diagram below shows the use of a flow-through chamber. This provides a compact installation
and is particularly suited to flows of contaminated fluids, since the design of the chamber encourages
self cleaning. Because the volume flow rate is low, the heat flow is low and therefore the insulation
must be as efficient as possible. The low heat flow makes this system ideal for base (or referred)
viscosity measurement using heat exchangers.
For information on installing a short-stem version of the 7827 digital viscosity meter, see Chapter 2.
3.1Introduction
All drawings and dimensions given in this manual are given here for planning purposes only. Before
commencing fabrication, reference should always be made to the current issue of the appropriate
drawings. Contact Micro Motion for details.
To protect the tines from damage, a Transit Cover is fitted prior to shipment from the factory. The Transit
Cover is held in place by 2 grub screws. Be sure to remove and store the Transit Cover prior to
installation. Re-fit the Transit Cover if storing or transporting, such as for repair. If the Transit Cover has
been lost, it can be purchased from Micro Motion.
For further information on handling and using the meter, see “Safety guidelines” on page 1
There are a variety of external factors that affect the ability of the 7827 digital viscosity meter to
operate successfully. In order to ensure that your system works correctly, the effects of these factors
must be taken into consideration when designing your installation.
There are two main aspects to consider:
•The accuracy and repeatability of the measurements
•The relevance of the measurements to the overall purpose of the system
Factors which may adversely affect accuracy and repeatability include:
•The presence of gas or bubbles within the fluid being measured
•Non-uniformity of the fluid
•The presence of solids as contaminants
•Fouling of the meter
•Temperature gradients
•Cavitations and swirls
•Operating at temperatures below the wax point of crude oils
In some applications, absolute accuracy is less important than repeatability. For example, in a system
where the control parameters are initially adjusted for optimum performance, and thereafter only
checked periodically.
Installation and Configuration Manual21
Installation (Long Stem)
The term achievable accuracy can be used to describe a measure of the product quality that can be
realistically obtained from a process system. It is a function of measurement accuracy, stability and
system response. High accuracy alone is no guarantee of good product quality if the response time of
the system is measured in tens of minutes, or if the measurement bears little relevance to the operation
of the system. Similarly, systems which require constant calibration and maintenance cannot achieve
good achievable accuracy.
Factors which may adversely affect the relevance of the measurements could include:
•Measurement used for control purposes being made too far away from the point of control, so
that the system cannot respond properly to changes.
•Measurements made on fluid which is unrepresentative of the main flow.
3.2Installation considerations
Density and viscosity is a sensitive indicator of change in a fluid - a key reason why density and
viscosity measurement is increasingly being chosen as a process measurement. However, density and
viscosity measurements can be sensitive to extraneous effects and, therefore, great care must be taken
to consider all the factors which may affect measurement when assessing the installation
requirements.
Like many other meters, the optimum performance of the viscosity meter depends upon certain
conditions of the fluid. You must first select a suitable position where the fork’s tines are always
completely immersed in the fluid. Although tolerant of solids, turbulence and bubbles, there should
be at least a 50 mm clearance from objects e.g. impellers, pipe stubs, etc.
Then consideration can be given to fluid conditioning at that point. Where the application
requirements allow a degree of tolerance in the point chosen for installation, the installation may be
able to take advantage of natural flow conditioning.
The choice of mechanical installation will be dictated partly by application needs and partly by the
fluid conditions, such as:
•Condition of fluid at the sensor.
•Flow rate.
•Entrained gas.
•Solids contamination.
3.2.1Fluid at the sensor
The fluid in the effective zone of the long stem 7827 meter must be of uniform composition and at
uniform temperature. It must be representative of the fluid as a whole. This is achieved by taking
advantage of any natural tank condition that tends to cause mixing, such as pump discharge, partially
open valves etc.
3.2.2Flow rate
If there is flow in the tank, the rate of flow should ideally be not more than 0.5 m
3
/s. If flow rates
exceed this, a ‘shift’ will be introduced into density and viscosity readings. The higher the flow rate
is, the larger the ‘shift’. Measurements also become ‘noisy’.
22Micro Motion 7827 Digital Viscosity Meter
Installation (Long Stem)
3.2.3Entrained gas
Gas pockets can disrupt the measurement. A brief disruption in the signal caused by transient gas
pockets can be negated in the internal signal conditioning software, but more frequent disruptions or
serious gas entrainment must be avoided. This can be achieved by observing the following
conditions:
•Vent any gas prior to the viscosity meter.
•Avoid sudden pressure drops or temperature changes which may cause dissolved gases to
break out of the fluid.
3.2.4Solids contamination
•Avoid sudden changes of velocity that may cause sedimentation.
•Install the meter far enough away from any build-up of solids.
•Maintain flow velocity at the sensor within the specified limits.
•Specify the long-stem 7827 meter with a non-stick PFA protective layer.
Only the safe area model may be used in open-tank installation.
1. For open-tank installations, the long-stemmed 7827 meter is clamped to a structure (see
Figure 3-1). The position of the clamp determines the insertion depth.
Figure 3-1Open-tank installation
2. Keep the tines away from the tank wall (see Figure 3-2).
Installation and Configuration Manual23
Installation (Long Stem)
Figure 3-2Keeping tines away from the tank wall (Open-tank)
3. Keep the tines immersed in fluid (see Figure 3-3).
Figure 3-3Keeping tines immersed (Open-tank)
4. Keep tines away from objects and disturbed flow (see Figure 3-4).
24Micro Motion 7827 Digital Viscosity Meter
Installation (Long Stem)
Figure 3-4Keeping tines away from objects and disturbed flow (open tank)
5. If there is flow, align the tines such that the flow is directed towards the gap between the tines
(see Figure 3-5).
Figure 3-5Aligning the tines in flow (Open-tank)
6. Keep away from deposit build-up (see Figure 3-6).
Installation and Configuration Manual25
Installation (Long Stem)
Figure 3-6Avoid deposit build-up (Open-tank)
3.4Closed-tank installation
1. For closed-tank installations, the long-stemmed 7827 meter should have a factory fitted flange
attachment. (This is an option that is specified as a code in the part number – see a list of the
product options in the product data sheet available at www.micromotion.com.) (See
Figure 3-7).
Figure 3-7Closed-tank installation
2. To vary the insertion depth, a standoff section with flange (not supplied) can be used (see
Figure 3-8).
26Micro Motion 7827 Digital Viscosity Meter
Installation (Long Stem)
Figure 3-8Use of standoff section (not supplied)(closed-tank)
3. Keep the tines immersed in fluid (see Figure 3-9).
4. Keep the tines away from the tank wall (see Figure 3-10).
Figure 3-10 Keeping away from tank wall (closed tank)
5. Allow for flexing of the tank lid, preventing the long-stemmed 7827 meter from being pushed
towards a tank wall or into the path of disturbed flow (see Figure 3-11).
Installation and Configuration Manual27
Installation (Long Stem)
Figure 3-11 Allowing for tank lid flexing (closed tank)
6. Keep tines away from objects and disturbed flow (see Figure 3-12).
Figure 3-12 Keeping tines away from objects and disturbed flow (Closed-tank)
7. If there is flow, align the tines such that the flow is directed towards the gap in the tines (see
Figure 3-13)
28Micro Motion 7827 Digital Viscosity Meter
Installation (Long Stem)
Figure 3-13 Aligning the tines in flow (closed tank)
8. Keep away from deposit build-up (see Figure 3-14).
The log-stemmed 7827 meter is factory calibrated and no further calibration is necessary. The
calibration is traceable to UK National Standards through the Micro Motion UKAS-approved
laboratory.
For calibration range, see the 7827 digital viscosity meter product data sheet available at
www.micromotion.com.
3.6If the Tank is Pressurized
1. Once the installation has been prepared, and before installing the 7827 meter, fit a blanking
flange or compression nut to the 7827 meter mounting, and pressurize and flush the system.
2. Isolate the system, depressurize and remove the blanking flange or compression nut.
3. Install the 7827 meter.
4. Slowly pressurize the system and check for leaks, particularly if the normal operating
temperature is high, or the sensor has been fitted cold; tighten as necessary.
Installation and Configuration Manual29
Installation (Long Stem)
5. Once the system has stabilized and is leak free, fit the insulation material, remembering also to
insulate any flanges.
30Micro Motion 7827 Digital Viscosity Meter
Electrical Connections
Chapter 4
Electrical Connections
For installations in hazardous areas:
•For ATEX installations, the electrical installation must strictly adhere to the safety information
given in the ATEX safety instructions booklet shipped with this manual. See Section 1.1 for
important information.
•For installations in USA and Canada, the electrical installation must strictly adhere to the Electrical
Codes and a conduit seal is required within 2” (50 mm) of the enclosure.
4.1Introduction
This chapter shows you how to wire up the 7827 digital viscosity meter and then connect it to the
Micro Motion
Note: Only Micro Motion signal converters and flow computers are able to interpret the signals from
the 7827 meter; it cannot be connected to equipment from other manufacturers.
4.2EMC and cabling considerations
To meet the EC Directive for EMC (Electromagnetic Compatibility) it is recommended that the meter
be connected using a suitable instrumentation cable and earthed through the meter body and
pipework. The instrumentation cable should have an individual screen, foil or braid over each twisted
pair and an overall screen to cover all cores. Where permissible, the screen should be connected to
earth at both ends. Note that for intrinsic safety, termination of the screen to earth in the hazardous
area is not generally permitted.
To electrically connect the 7827 to a Micro Motion 795x series computer you will need the following:
•Minimum of 7-core screened twisted pairs with overall screen
•795x connector plugs:
79507951 Klippon7951 D-type (Cannon)
2 off 10-way2 off 10-way2 off 25-way
1 off 4-way1 off 4-way1 off 4-way
•1/2" NPT to M20 x 1 Exd IIC-rated gland adaptor
•M20 x 1 Exd IIC-rated cable gland
•1/2" NPT Exd IIC-rated blanking plug
•Hex drive, 2.5 mm AF (2.0 mm AF stainless steel enclosure)
•Electrical screwdriver, 3 mm drive
•Wire strippers
•Gland spanners / drives
Installation and Configuration Manual31
Electrical Connections
GRUB
4.3Installation and safety in hazardous areas
For installations in hazardous areas:
•For ATEX installations, the electrical installation must strictly adhere to the safety information
given in the ATEX safety instructions booklet shipped with this manual. See Section 1.1 for
important information.
•For installations in USA and Canada, the electrical installation must strictly adhere to the Electrical
Codes and a conduit seal is required within 2” (50 mm) of the enclosure.
The 7827 meter is explosive proof and can be installed in a hazardous area without the use of
intrinsically safe barriers (or isolators). However, it is still necessary to observe the rules of
compliance with current standards concerning flameproof equipment:
•The meter electronics housing covers must be tightened securely and locked into position by
their locking screws.
•The electrical conduit must be fitted with an appropriate explosion-proof cable gland.
•If any electrical conduit entry port is not used it must be blanked off using the appropriate
explosion-proof plug, with the plug entered to a depth of at least five threads.
•The spigot must be locked into place.
•The cabling used to wire the 7827 to the signal converter/flow computer must be of the
appropriate Exd rating.
4.4Installation in non-hazardous areas
Typically the 7827 meter will operate over cable lengths up to 2 km from a 24 V supply.
Micro Motion recommend cables similar to BS 5308 or RS 368.
4.5Wiring the meter
1. Open the Terminal Board side of the
meter’s electronics housing by
undoing the grub screw and
unscrewing the lid anticlockwise.
UNDO THIS CAP
SCREW
32Micro Motion 7827 Digital Viscosity Meter
Electrical Connections
HOLE
1/2" NPT PLUG Ex d IIC
1/2" TO M20 x 1 ADAPTOR
M20 x 1 CABLE GLAND
Exd IIC
T
TB3 TB1
TB2
200 mm OF UN S CREEN ED WIR E
TERMINAL BOARD
A
CABLE GLAND
SU
G
PR T
SIGNAL -
SIGNAL +
SUPPLY -
SUPPLY +
PRT POWER +
PRT SIGNAL +
PRT SIGNAL -
PRT POWER -
k
Note: “S upply-”
& “Signal -” are
linked internally
NEST WIRES
PRT
Term 1
SUPPLY SIG
+ - + -
2. The meter is normally mounted
horizontally such that the 1/2” NPT
holes are on a vertical plane. This
minimizes water ingress. Identify the
1/2" NPT hole which is lowest and
attach the multi-core cable to it.
3. Assemble the adaptor, cable gland and
cable so that the multi-core cable is
gripped leaving 200 mm of free,
unscreened wire to connect to the
terminal blocks.
4. Fix the 1/2" NPT plug to the un-used
hole.
5. The adjacent diagram shows all the
electrical connections to the meter
terminal block. Refer to Section 4.6
for connections to the 795x.
the correct terminals, carefully tuck
the wires around the electronics, and
tighten the cable gland.
Fi gure 3. 1: Electrical connections to 7827 main termi nal bloc
erm 8
Electrical Connections
7. Screw the housing cap on fully and
tighten the locking grub screw using
the 2.5 mm AF hex drive.
4.6Connecting the 7827 to a 795x series computer
4.6.1Overview
The 7827 requires a 795x series computer (Signal Converter or Flow Computer) with liquid-based
application software for it to be functional. This section provides a guide to possible wiring
connections between the 7827 and the 795x. Configuration of the 795x is outside the scope of this
manual. For this task, refer to the 795x operating manual that was supplied with the 795x instrument.
795x computers are available as a 7950 Wall Mount unit or 7951 Panel Mount unit. Each type of unit
has a different position and layout for the physical connections. There is even a choice of two
connection panels for the 7951 - Klippon or D-type (Cannon).
TIGHTEN
CAP
TIGHTEN
GRUB
:
795xConnectors used
795010-way Klippon
795125-way D-type (Cannon) or 10-way Klippon
Note: The choice of rear panel connectors for the 7951 is done prior to ordering the unit so that it is
manufactured to satisfy the customers connector requirement.
This section has diagrams of connections, involving the 7827, for the full 795x range:
•7950 Signal Converter
•7950 Flow Computer
•7951 Signal Converter
•7951 Flow Computer
Note: “Signal Converter” and “Flow Computer” are terms that are often used to identify the basic
purpose of the 795x application software. Refer to the supplied 795x operating manual if in doubt
about identification.
Use this table to quickly find the appropriate connection diagrams.
795xFigureNo. of 7827s
7950Signal ConverterFigure 4-11
34Micro Motion 7827 Digital Viscosity Meter
Electrical Connections
Signal -
PRT Signal -
PRT Signal +
PRT Power +
PRT Power -
0V Supply
S i gn al +
+24V Power
Sig +
PL12/4
PL12/3
PL12/2
PL12/
PL9/8
PL9/6
5
p
p
Signal -
PRT Signal -
PRT Signal +
PRT Power +
PRT Power -
0V Supply
S i gn al +
+24V Power
Sig +
PL7/4
PL7/3
PL7/2
PL7/1
PL5/10
PL5/3
PL5/9
PL5/4
SK 6 /24
SK 6 /22
p
1
p
g
y
7950Flow ComputerFigure 4-22
7951Signal ConverterFigure 4-11
7951Flow ComputerFigure 4-32
4.6.2Connection diagrams
Figure 4-1Connecting a 7827 to a 7950/51 Signal Converter
-" connection on the 7827 is not shown since it is
linked to the "Supply -" connection. There is no need
The "Si
internall
external link.
4.7Checking the installation
After installation, the following procedure will indicate to a high degree of confidence that the meter
is operating correctly.
PRT Power -
Sig nal -
PL8/
PL8/6
SK8/
SK8/ 6
PRT Input #4
ins on the 7951
Installation and Configuration Manual37
Electrical Connections
Electrical checks
Measure the current consumption and the supply voltage at the meter amplifier. They should be
within the following limits:
•Current: 40 mA to 70 mA (Measured in series at the “SUPPLY +” terminal)
•Voltage: 22.8 V to 25.2 V (Measured between” SUPPLY +” and “SUPPLY -” terminals)
Functionality checks
1. When the meter is powered up, a small audible continuous ringing sound can be heard with a
“Ping” occurring at 1 second intervals.
2. With the meter clean and dry, and with the tines shielded from the wind, operate it in air and
check that the meter frequency output (τ
density air point check. If the ambient conditions are not at 20°C (±2°C), use the formula
below to calculate the resulting time period:
The result (τ
certificate to within ±0.5 μsec.
Note: The air check point is found in the Density Calibration section of the Viscometer calibration
certificate.
), is as specified on the meter calibration certificate
The 7827 meter is calibrated against fluids characterized with prime standards, prior to leaving the
factory. The meter may be calibrated over one or a combination of four viscosity ranges detailed
below:
•Range:Viscosity range (cP)
•Ultra-low: 0.5 - 10 cP
•Low:1 - 100 cP
•Medium:100 - 1,000 cP
•High:1,000 - 12,500 cP
The 7827 meter’s default calibration is in “free stream” conditions, where the effect of solid
boundaries is negligible on the output of the meter. The calibration may also be performed in a
“tee-piece,” in which case the part number above is succeeded by a “T”.
Note: A high-range unit cannot be ordered with a tee-piece calibration.
Hygienic units can be calibrated in a 3” hygienic bore if required.
Three fluids are used to establish the general viscosity equation's constants for each viscosity range
required. See the Calculated Parameters appendix.
The instrument-under-test is immersed into the calibration fluid which has been previously
characterized for viscosity and density with prime standards. Great attention is paid to temperature
equalization and fluid homogeneity within the tank before the calibration data is taken. This
procedure is repeated for each calibration fluid and for each viscosity calibration range required.
Once the meter has been passed through the necessary fluids, a factory calibration certificate is
produced from the measurement data.
Installation and Configuration Manual41
Calibration Check
A fourth fluid is used as an overcheck to verify the calibration for each viscosity range. Each check is
monitored by the Micro Motion Quality Assurance Department.
6.2.2Density
The 7827 meter is calibrated within the standard shroud against Transfer Standard instruments
traceable to National Standards, prior to leaving the factory. Three fluids ranging in density from 1 to
1000 kg/m
are derived from the air point and material properties.
The calibration procedure relies on units being immersed in fluids whose density is defined by
Transfer Standards. Great attention is paid to producing temperature equilibrium between the fluid,
the unit under test and the Transfer Standard. In this way, accurate calibration coefficients covering
the required density range can be produced.
All instruments are over-checked on water to verify the calculation. The check is monitored by the
Micro Motion Quality Assurance Department.
Where viscosity correction is concerned, the temperature measurement from each viscosity
calibration fluid taken is translated into density through a previous characterization of the fluid using
prime standards. This method is used to assess the density offset due to viscosity for each viscosity
calibration range not including the 1 to 100 cP range, as the viscosity effect only becomes significant
at viscosities greater than 100 cP.
3
are used to establish the general density equation constants. The temperature coefficients
Once the meter has been calibrated with the necessary fluids a factory calibration certificate is
produced from the measurement data.
6.2.3Primary standards
The fluids used in the viscosity calibration have been characterized for viscosity and density versus
temperature in between 15°C and 25°C. This is done using BS/U “U-tube” capillary viscosity meters
for kinematic viscosity measurement and pyknometers for density measurements. Both of these
methods are Primary Measurement Systems conforming to BS188 and BS733 Part 1 respectively.
The calibration of the calibration fluids is performed under closely controlled laboratory conditions.
A calibration certificate is issued. Calibrations are repeated, typically every six months, producing a
well documented history of the fluid.
6.2.4
Transfer standards
The Transfer Standard instruments used in the density calibration are selected instruments which are
calibrated by the British Calibration Service Laboratory and certified.
Transfer Standard calibration uses a number of density-certified liquids, one of which is water. The
densities of these reference liquids are obtained using the Primary Measurement System whereby
glass sinkers of defined volume are weighed in samples of the liquids.
Calibration of the Transfer Standard instruments is performed under closely controlled laboratory
conditions. A calibration certificate is issued. Calibrations are repeated, typically every six months,
producing a well-documented density standard.
42Micro Motion 7827 Digital Viscosity Meter
Calibration Check
V1' = V1 + Q2 * ( η
actual
- η
calc
)
6.3In-line calibration
6.3.1Viscosity
The 7827 meter is calibrated to operate in installations where the boundary formed by the surrounding
metalwork is at a distance away where it does not influence the viscosity reading from the meter. If
the installation is such that an error in viscosity is seen due to the proximity of the metalwork to the
tines, an in-line calibration is needed to correct for this source of error.
To perform an in-line calibration it is necessary to know the actual dynamic viscosity and temperature
of the calibrating fluid along with both time periods from the meter. The fluid dynamic viscosity at
these operating conditions may be determined by using a suitable conventional viscometer/rheometer
or by measuring the fluid's kinematic viscosity and multiplying by the fluid's actual density (in g/cc).
The procedure for calculating the new calibration coefficients V1' for the particular viscosity range
currently selected is that shown below:
•where V1' = New V1 calibration coefficient for current viscosity range and installation only
•V1 = Original V1 calibration coefficient for current viscosity range
•Q = meter quality factor value in calibration fluid and installation
•η
•η
= Actual fluid viscosity (measured from a standard) – (cP)
actual
= Calculated fluid viscosity (using original coefficients and Q below) – (cP)
calc
Note: The value of V1' is now used in the general viscosity equation in the 795x replacing the original
values of V1 on the calibration certificate for this application only and for this viscosity range only.
If the process viscosity is variable, the calibration should be tested at the maximum, minimum, and
mid-point values of the process viscosity range, to check that the V1 correction is sufficient.
6.3.2Density
The 7827 meter is calibrated to operate in installations where the boundary formed by the surrounding
metalwork is at a distance away where it does not influence the density reading from the meter. If the
installation is such that an error in density is seen due to the proximity of the metalwork to the tines,
an in-line calibration is needed to correct for this source of error.
To perform an in-line calibration it is necessary to know the actual density and temperature of the
calibrating fluid along with the time period B from the meter. The fluid density at these operating
conditions may be determined by using using one of the methods outlined below:
For stable liquids
Draw off a sample of the liquid into a suitable container, at the same time note the density and the
operating temperature. Measure the density of the sample under defined laboratory conditions using a
hydrometer or other suitable equipment.
Note: It is essential that you have a good understanding of the physical properties (temperature
coefficient, etc.) of the liquid and that tables of such data are available when using this method.
Installation and Configuration Manual43
Calibration Check
For unstable or high-pressure vapor liquids
A pressure pyknometer can be used. The pressure pyknometer and its associated pipework can be
coupled to the pipeline so that a sample of the product flows through it. When equilibrium is reached,
the meter density reading is noted as the pyknometer is isolated from the sample flow. The
pyknometer is removed for weighing to establish the product density. This density result is now
compared with the reading from the meter.
For further details on these procedures, reference should be made to:
Energy Institute:HM7. Density, sediment and water. Section 1: General
guidance on test methods (formerly PMM Part VII, S1)
1st ed 1996 ISBN 978-0-85293-154-7
Energy Institute:HM8. Density, sediment and water. Section 2: Continuous
density measurement (formerly PMM Part VII, S2)
2nd ed Sept 1997 ISBN 978-0-85293-175-2
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 vapour pressure, April 1991.
The procedure for calculating the new calibration coefficients K0' and K2' from the data derived
above is illustrated in Figure 6-1.
6.3.3Requirements for VOS correction
This correction only needs to be applied if one or more of the following conditions exist concerning
the calibration fluid used and the eventual product fluid being measured:
•The VOS of the calibration fluid is appreciably different to that of the measured fluid.
•The VOS and density of the calibration fluid are significantly displaced from the optimized
profile (see the Calculated Parameters appendix).
•The VOS of the product fluid changes significantly with temperature.
44Micro Motion 7827 Digital Viscosity Meter
Calibration Check
START
IS VOS
REQUIRED?
VOS CORRECTION
METHOD GRAPHICAL
OR ANALYTICAL
SOLUTION?
ANALYTICAL
GRAPHICAL
YES
DETERMINE DENSITY
OFFSET
dD
L
FROM
V
A
AND
D
L
(fig B.1)
CALCULATE
D'
L
=
D
L
-
dD
L
IF 0.3g/cc <
D
L
< 1.1g/cc
V
C
= 64.1 + 1.414*
D
L
IF 1.1g/cc <
D
L
< 1.6g/cc
V
C
= 2346 + 0.660*
D
L
D
t
= __________________
D
L
-
K19*(t
L
- 20)
1 +
K18*(t
L
- 20)
D'
L
=
D
L
NO
A
=
V
C
-
V
A
B
= 2900 -
D
L
+ A*24.0E+06
D'
L
= 0.5*[-B + B + 11600*
D
L
]
2
-2
-2
K0'
= -1.04 - K1*
T
A
-
K2'*T
A
2
K2'
= __________________
-1.04 -
D
t
- K1*(
T
A
-
T
L
)
T
A
-
T
L
2
2
Where:
• DL= Actual density of calibrating
liquid
• D
t
= DL corrected for meter
temperature
• t
L
= Temperature of calibrating
liquid
• dD
L
= Density offset of calibrating
liquid from VOS profile (fig. B.1)
• D’
L
= VOS corrected density of
calibrating liquid
• τ
BA
= Time period B from the meter
in air (on calibration certificate)
• τ
BL
= Time period B in the
calibrating liquid
• V
A
= Actual VOS of calibrating
liquid
• V
C
= Calibration VOS
(For details of the VOS correction
method, refer to the Calculated
Parameters appendix.)
Note: The values of K0' and K2' are now used in the general density equation in the 795x, replacing
the original values of K0 and K2 on the calibration certificate for this application only.
6.4.1Viscosity
The 7827 meter is calibrated for viscosity between 15°C and 25°C and at atmospheric pressure using
specified fluids which demonstrate Newtonian behavior.
Calibration Check
Viscosity calibration is effectively immune to temperature or pressure errors when operating with
Newtonian fluids.
As a general guide, Table 6-1 shows the accuracy of the 7827 meter:
Table 6-1Error sources on indicated viscosity
Error source7827
A. Instrument accuracy (with Newtonian fluids)±0.2 cP for 0.5-10 cP range
6.4.2Density
The 7827 meter is calibrated for density at 20°C and at atmospheric pressure using specified fluids.
When operating at other conditions it is necessary to increase the uncertainty of measurement, either
by the magnitude of the offsets if no corrections are applied, or by a fraction of the offsets if
corrections are applied.
As a general guide, Table 6-2 lists the sources and magnitudes of the offsets affecting the meter:
--------------
where D = Density (uncorrected) | FINAL TEST & |
Dt = Density (temperature corrected) | INSPECTION |
Dv = Density (temp and viscosity corrected) | |
TB = Time period B (uS ) | |
Q = Quality Factor | |
t = Temperature (°C) --------------
Ref No:- LV7827/V6.2 DATE : 30JUL08
Figure 6-2Example calibration certificate for the 7827 digital viscosity meter
The 7827 meter system has no moving parts thereby reducing the maintenance requirements to simple
visual checks for leaks, damage to the meter and interrogating the 7950 and 7951 signal converters.
The following procedure is recommended for any periodic maintenance carried out on the system and
forms the basis of any fault finding task:
1. Examine the meter, its amplifier housing and cables for any signs of damage or corrosion.
2. Make sure that the spigot connection to the amplifier housing is tight.
3. Check the meter and flanging for signs of leakage.
4. Check that there is no ingress of water/fluid into the amplifier housing.
5. Ensure that the threads on the covers of the amplifier housing are well greased (graphite
grease) and that the 'O' rings are in good condition.
The electronics housing is designed for IP 66 environmental rating which means that,
providing the caps and plugs are correctly assembled, no moisture or dust is able to penetrate
through to the electronics.
The electronics housing is rated for explosion proof to Exd IIC and Class I Division Gas
Groups C & D classification. The covers MUST be completely screwed down and, in the case
of an explosion proof enclosure application, DO NOT FAIL to tighten the locking screws
(Aluminium enclosure 2.5 mm hex A/F; Stainless steel enclosure 2.0 mm hex A/F). (For more
information on the safety certification, see the Safety Certification appendix.)
Installation and Configuration Manual49
General Maintenance
6. Check that the Signal Converter is providing adequate power to the meter and that the Signal
Converter itself is functioning properly.
Check calibrations should be carried out at specified intervals in order to highlight a malfunction or
deterioration in meter performance. If a fault or a drop in performance is discovered, further tests – as
described in "fault analysis" below – are required to identify the cause of the fault. When a fault has
been traced, actions to rectify the fault may include making good any poor connections, replacing the
amplifier board, or in extreme cases the complete meter, Signal Converter, or both.
(For details of carrying out a check calibration, refer to Chapter 6).
7.3Fault analysis
A fault may be described as falling in one of three categories:
•Readings unsteady
Normally caused by the presence of gas bubbles around the tines. Severe electrical
interference, severe pipeline vibrations, electrical and electronic faults can also cause this
effect.
•Readings outside limits
Normally caused by deposition and/or corrosion on the tines. Electrical and electronic faults
can also cause this effect.
•Readings not updating
Normally caused by memory locations within the Signal Converter being SET when they
should be FREE and by wiring open circuits between Signal Converter and meter.
Checking values in Signal Converter locations is easier than checking electrical power consumption,
which in turn is easier than physical inspection, so faults should therefore be considered in this order.
7.3.1Checking the Signal Converter
All of the 7827 meter's results are compiled from four main parameters:
•Time period A (τ
•Time period B (τ
)
A
)
B
•Temperature from the PRT
•Quality factor (Q) is obtained from τ
& τ
A
B
Hence, if instability or inaccuracy of the indicated viscosity or density exists, these parameters should
be checked first.
Error on indicated viscosity
If the indicated viscosity is in error, follow the table below and, if necessary, refer to the other tables
later in the chapter to find the cause of the fault.
50Micro Motion 7827 Digital Viscosity Meter
General Maintenance
Table 7-1Error checking for viscosity
What to check:What to look for:What to check next:
Indicated viscosityReading unsteady
• Time periods τA & τB (below).
(more than ±5 cP)
Reading out of limits• Do the calibration coefficients programmed into the Signal
Reading not updating• Is the viscosity value FREE on the Signal Converter?
• Is the viscosity signal input 0 V connection (PL2 pin2)
connected to 0V on the Signal Converter (PL1 pin 4)?
• If the readings are still unsteady, the installation is probably
the cause of the fault (see Section 7.3.3 below).
Converter match those on your factory calibration certificate?
• Does the value of Q match that inferred from the table of set
viscosities shown on your factory calibration certificate?
• Is the viscosity more than the “viscosity high limit” value? SET limit value to "1.00E+99" to find out.
• Is the viscosity less than the “low viscosity limit” value? - SET
limit value to "-1.00E+99" to find out.
• Has the fluid viscosity actually changed to the value shown?
Compare a sample measured with a known viscosity
standard with the 7827 meter.
• Product build-up on tines (see Section 7.3.3 below).
• Corrosion or erosion on the tines (see Section 7.3.3 below).
• Non-Newtonian fluid. Contact Micro Motion.
• Are both time period values FREE in the Signal Converter?
(Below)
• Is the viscosity more than the “viscosity high limit” value? SET limit value to "1.00E+99" to find out.
• Is the viscosity less than the “low viscosity limit” value? - SET
limit value to "-1.00E+99" to find out.
• Check connections between 7950/1 and 7827 meter (below).
• Meter not powered correctly: Check consumption at the
meter (below).
• Fault with 7950/1: Refer to the 7950/1 Handbook, then
contact Micro Motion if fault persists.
If the indicated density is in error, follow the table below and, if necessary, refer to the other tables
later in the chapter to find the cause of the fault.
Installation and Configuration Manual51
General Maintenance
Table 7-2Error checking for density
What to check:What to look for:What to check next:
Indicated density
(loc 014)
Reading unsteady
(more than ±1kg/m
Reading out of limits• Do the calibration coefficients for density programmed into the
Reading not updating• Is the density value FREE on the Signal Converter?
• Time period τ
3
• Is the signal input 0V connection (PL2 pin2) connected to 0V
)
on the Signal Converter (PL1 pin 4)?
• If the reading is still unsteady, the installation is probably the
cause of the fault (see Section 7.3.3 below).
Signal Converter match those on your factory calibration
certificate?
• Is the temperature input FREE and reading correct)?
• Do the calibration coefficients for temperature correction on
density programmed into the Signal Converter match those on
your factory calibration certificate?
• Do the calibration coefficients for viscosity correction on
density programmed into the Signal Converter match those on
your factory calibration certificate?
• Have you selected "VOS correction" and left the value of fluid
VOS) set to an incorrect value, e.g. 0?
• Is the indicated density greater than the “density high limit”
value? - SET limit value to "1.00E+99" to find out.
• Has the fluid density actually changed to the value shown?
Compare a sample measured with a known density standard
with the 7827 meter.
• Product build-up on tines (see Section 7.3.3 below).
• Corrosion or erosion on the tines (see Section 7.3.3 below).
• Are both time period values FREE in the Signal Converter?
(Below)
• Are the temp corrected density, viscosity corrected density and
uncorrected density values all free in the signal convereter?
• Is the line density greater than the “density high limit” value? SET limit value to "1.00E+99" to find out.
• Check connections between 7950/1 and 7827 meter (below).
• Meter not powered correctly: Check consumption at the meter
(below).
• Fault with 7950/1: Refer to the 7950/1 Handbook, then contact
Micro Motion if fault persists.
(below).
B
7.3.2Checking the power consumption
A lot of information is gained from checking the power consumption at various parts of the circuit
between Signal Converter and meter.
Table 7-3Electrical error checking
What to check:What to look for:What to check next:
Voltage at meter:
Across " + " & " - " terminals
Current at meter:
In series with " + " terminal
52Micro Motion 7827 Digital Viscosity Meter
22.8 V to 25.2 V dcCorrect voltage supplied to meter electronics.
0 V dcThere is an open circuit on the power line
between the meter and Signal Converter.
0 mAElectronics not drawing current:
Check wiring for open circuits.
25 mA to 40 mAElectronics drawing the correct amount of
current.
General Maintenance
Table 7-3Electrical error checking continued
What to check:What to look for:What to check next:
Voltage at viscosity signal input
on Signal Converter:
Across PL2, pins 1 & 2
Resistance at PRT:
Across " + SIG " & " - SIG "
terminals
> 60 mAElectronics drawing excessive current: There is
a fault with the maintaining amplifier board.
Contact Micro Motion for replacement
electronics.
5 V to 15 V dc, switching
to 0 V
High or low constant
voltage
80 Ω to 160 ΩCorrect resistance lower and upper limits for
Out of rangeThe PRT has gone open circuit:
0 ΩThe PRT wiring has short circuited:
Correct waveform being sent from the meter.
The meter is not supplying the Signal Converter
with the correct waveform. Contact Micro
Motion for replacement electronics.
meter's operating temperature range. For an
exact resistance value for the line temperature,
see the Product Data appendix.
Check associated wiring. If unrepairable,
contact Micro Motion.
Check associated wiring. If unrepairable,
contact Micro Motion.
The last check to be made is a physical check of the meter's installation and wetted parts. This means
taking the 7827 meter out of the installation and inspecting the tines and pipeline immediately
surrounding the flange. This check should serve to confirm the presence of build-up or erosion on the
tines.
Table 7-4Installation checks
What to check:What to look for:What to check next:
Presence of bubblesLeaky pipework.• Flanging correctly aligned, sealed and
Listen for "popping" inside
the line.
Pumps or agitators
nearby.
Flow rateDetermine the flow
velocity through the
pipeline.
Determine the distance
between the flange face
and the inside bore of the
pipeline.
tightened.
• Increase the pipeline pressure.
• Align the pipework correctly to prevent
vortices being shed.
• Pumps and agitators may be generating
bubbles from dissolved gases.
• Refer to the appropriate Installation chapter
for your meter to see what maximum flowrate
is allowable for the mounting configuration
you have chosen.
• Refer to the appropriate Installation chapter
for your meter to see what this distance
should be for the mounting configuration you
have chosen.
Installation and Configuration Manual53
General Maintenance
Table 7-4Installation checks continued
What to check:What to look for:What to check next:
Installation dimensionsCheck the key dimensions
Product build up on the tinesProduct which has stuck
Corrosion or erosion on the tines Scratches, pits or a
as specified in Chapter 2
for your installation.
to the tines
change in surface finish of
the tines.
• Your key dimensions should match those
detailed in the Installation chapter for your
meter for your mounting configuration.
• Remove with a suitable solvent.
• Recalibration is highly recommended.
• Where corrosion is a known problem, periodic
recalibration is recommended at time
intervals to suit the rate of corrosion of the
tine material.
54Micro Motion 7827 Digital Viscosity Meter
Appendix A
Calculated Parameters
A.1Introduction
The following information details the equations used in the Micro Motion
translate the raw data from the meter into fluid parameters and covers the following:
To derive the fluid's dynamic viscosity the frequency of oscillation at two points on the meter's
resonance curve are taken, manipulated to calculate the meter's quality factor (Q) and then calibrated
against actual fluid viscosity determined by a prime standard.
(For details of the principle of operation, see Chapter 1.)
The Quality factor from the 7827 meter is calibrated against the fluid’s dynamic viscosity in
centiPoise (cP). The order in which the calculations are applied are according to the following.
A.2.1Quality factor
The meter operates at two time periods (τ
the frequency spectrum. In doing this, one may calculate the meter's quality factor by using the
following equation:
Q = 1 / [ ( τ
/ τB )
A
Where:
•Q = Quality factor of meter (no units)
•τ
•τ
= Time period A of meter (µsec)
A
= Time period B of meter (µsec)
B
0.5
- ( τB / τA )
and τB) which correspond to the two –3 dB level points on
A
0.5
][1]
Installation and Configuration Manual55
Calculated Parameters
A.2.2General viscosity equation
The quality factor of a resonator is proportional to the inverse square root of viscosity. To calibrate
the resonator against fluid viscosity, the following quadratic expression is used:
η = V * ( V0 + V1.*X + V2*X
Where:
•η = Fluid dynamic viscosity (cP)
•V = Dynamic viscosity scaling factor (1 = cP)
•X= 1/Q
•V0, V1, V2 = meter calibration coefficients for each calibrated range
(For details of how to display alternative units, refer to the 795x Operating Manual.)
A.3Density equations
2
)[2]
2
(inverse square of the quality factor)
To determine the fluid's density, the smaller of the two time periods (τ
) is taken and used in a series
B
of equations to calibrate against actual fluid density determined by a transfer and prime standards.
The order in which the calculations are applied according to the following.
A.3.1General density equation
The time period of a resonator is proportional to the square root of density. To calibrate the resonator
against fluid density, the following quadratic expression is used:
ρ
= K0 + K1*τB + K2*τ
u
2
B
[3]
Where:
•ρ
•τ
= Fluid uncorrected density (kg/m3)
u
= Time period B of meter (µsec)
B
•K0, K1, K2 = meter calibration coefficients
The calibration takes place at 20°C and 1 bar.
A.3.2Temperature correction equation
If the meter operates at a temperature other than 20°C, a correction to the indicated density must be
made to account for the change in tine material characteristics with temperature. The following
equation is used:
If the meter is used in fluids whose viscosity is greater than 100 cP, a correction to the indicated
density must be made to account for the offset seen due to the fluid's viscosity. The following
equation is used:
56Micro Motion 7827 Digital Viscosity Meter
Calculated Parameters
ρv = ρt - [ K20 + K21*X + K22*X2][5]
where:
•ρ
v
•ρ
t
•X= 1/Q
•K20, K21, K22 = Meter calibration constants for each calibrated range
Note: Viscosity correction on indicated density is not needed where the fluid viscosity is less than
100 cP as the effect may be considered negligible.
A.3.4Pressure correction
The meter design is such that the influence of the line pressure on the indicated density measurement
is a negligible amount and can be ignored.
If the Velocity Of Sound (VOS) of the process fluid deviates substantially from the optimised
VOS/density profile shown in Figure A-1, it may be desirable to apply a correction. This may be
achieved by a simple introduction of an offset using the data from Figure A-1. Adjustment of the
value of K0 in the general density equation will achieve this. Alternatively, the following correction
equations may be used:
ρ
= ρv * [ 1 + ( 24.0E+06 / (ρv + 2900) ) * ( 1/ V
vos
2
- 1/ V
C
2
) ][6]
A
Where:
•ρ
•ρ
•V
•V
V
may be obtained direct from Figure A-1 or may be calculated as follows:
C
•V
•V
The value of V
= VOS-corrected density (kgm-3)
vos
= Viscosity-corrected density (kgm-3)
v
= Calibration VOS (m/s)
C
= Actual fluid VOS (m/s)
A
= 64.1 + 1.414 * ρv – for ρv of 300 kg/m3 to 1100kg/m
C
= 2346 - 0.660 * ρv – for ρv of 1100 kg/m3 to 1600kg/m3[8]
C
is calculated by the Signal Converter when VOS-correction is applied in the software.
C
3
[7]
Installation and Configuration Manual57
Calculated Parameters
0
500
1,000
1,500
2,000
2004006008001,0001,2001,4001,600
+1 kg/m
3
+0.5 kg/m
3
OPTIMISED
-0.5 kg/m
3
-1 kg/m
3
Density (kg./m3)
F
l
u
i
d
a
c
t
u
a
l
v
e
l
o
c
i
t
y
o
f
s
o
u
n
d
(
m
/
s
)
Figure A-1The Velocity Of Sound (VOS) / density relationship
A.3.6Density scaling
Once the indicated density has been corrected for temperature, viscosity and VOS, the result is scaled
to display density in any set of units. The following expression is used:
ρ = ρ
* K[9]
vos
Where:
•ρ= Displayed density (kg/m
•ρ
= VOS-corrected density (kg/m3)
vos
•K = Density scaling factor (1 = kg/m
A.4Kinematic viscosity equation
To derive the fluid's kinematic viscosity the dynamic viscosity and density must be known. The 7827
meter can provide both of these parameters and is therefore able to offer this as a standard output
using the following equation:
ν = U * 1000 * [ ( η / V ) / ( ρ / K ) ][10]
Where:
•ν= Fluid kinematic viscosity (in cS)
•U = Kinematic viscosity scaling factor (1 = cS)
•η= Fluid dynamic viscosity
•V = Dynamic viscosity scaling factor
•ρ= Fluid density
•K = Density scaling factor
The equation includes the dynamic viscosity and density scaling factors to ensure that the kinematic
viscosity is always calculated in centiStokes (cS). This result is then scaled by the kinematic viscosity
scaling factor (U) to scale the result to display other units of kinematic viscosity. (For details of how
to display alternative units refer to the 795x Operating Manual.)
3
)
3
)
58Micro Motion 7827 Digital Viscosity Meter
Safety Certification
Appendix B
Safety Certification
B.1Safety certification
Please contact Micro Motion if you need to have copies of the latest safety certification for the 7827
digital viscosity meter.
The above tables are derived from equations, which form the basis of the data in the Revised
Petroleum Measurement Tables (IP 200, ASTM D1250, API 2540 and ISO R91 Addendum 1).
The density temperature relationship used is:
3
Where:= Density at line temperature t°C (kg/m
= Density at base temperature 15°C (kg/m
)
3
)
= t°C –15°C (such as t – base temperature)
= Tangent thermal expansion coefficient per °C at base temperature 15°C
The tangent thermal expansion coefficient differs for each of the major groups of hydrocarbons. It is
obtained using the following relationship:
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.2New 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.
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 and Configuration Manual67
Return Policy
68Micro Motion 7827 Digital Viscosity Meter
Micro Motion USA
Worldwide Headquarters
7070 Winchester Circle
Boulder, CO 80301
T +1 303-527-5200
+1 303-522-6277
F +1 303-530-8459
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Tokyo 140-0002 Japan
T +81 3 5769-6803
F +81 3 5769-6844