Flomec EGM Series User manual

EGM Series Oval Gear Flow-meters
Operation Manual
Version 18.16

2
General Information
This manual provides the necessary information for operation and maintenance
of your Oval Gear flow-meter; for information on any integral electronics or
accessories fitted to your flow-meter please consult the relevant electronics or
accessory manual. Your Oval Gear flow-meter should only be installed and
maintained by persons familiar with local regulations, particularly those for
workplace Health and Safety.
For best results, please make yourself familiar with the contents of all relevant
product manuals prior to installation and commissioning. If further assistance is
required please consult the distributor from whom you purchased your flow-
meter.
Your flow-meter and any associated electronics are precision instruments,
to avoid unnecessary damage please treat them with care.
CAUTION

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Table of Contents
1. Introduction ...................................................................................................4
1.1 Operating Principle ..........................................................................................4
1.2 Specifications ...................................................................................................5
1.2.1 Small Capacity Models..............................................................................5
1.2.2 Medium Capacity Models.........................................................................6
1.2.3 Electrical Specifications ............................................................................7
2. Pre-Installation ..............................................................................................8
2.1 Pre-Installation Testing....................................................................................9
3. Mechanical Installation ................................................................................10
3.1 Installation Orientation .................................................................................10
3.2 Piping Construction........................................................................................11
3.3 Filtration / Straining ......................................................................................12
3.4 Pipe Connections............................................................................................12
3.5 Fuel Consumption Measurement...................................................................13
4. Electrical Installation....................................................................................14
4.1 Wiring ............................................................................................................14
4.2 Hall Effect Outputs.........................................................................................15
4.3 RTD Output (PT100).......................................................................................16
4.4 Wiring Diagrams............................................................................................17
4.4.1 Standard Pulse Output Board.................................................................17
4.4.2 Fuel Consumption Option ......................................................................17
4.4.3 Fuel Consumption Wiring with F127 Flow Computer ............................18
4.5 Meter Calibration Factor (K-Factor, Scale Factor) .........................................18
5. Commissioning.............................................................................................19
6. Maintenance ................................................................................................20
6.1 Parts Identification ........................................................................................21
6.2 Flowmeter Disassembly .................................................................................22
6.3 Flowmeter Inspection ....................................................................................22
6.4 Re-assembly of Flowmeter.............................................................................22
7. Spare Parts...................................................................................................23
7.1 Small Capacity Models...................................................................................23
7.2 Medium Capacity Models ..............................................................................24
8. Troubleshooting...........................................................................................25
8.1 Fault Finding ..................................................................................................25
8.2 Troubleshooting Guide ..................................................................................26

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1. Introduction
The Oval gear meter is a precise positive displacement flow-meter incorporating a pair of
oval geared rotors. These meters are capable of measuring the flow of a broad range of
clean liquids.
Stainless Steel flowmeters are suited to most liquid products and chemicals; including many
water based liquids, acids, bases and salt solutions, and Aluminium meters are suitable for
fuels, fuel oils & lubricating liquids.
EGM Series Oval Gear flow-meters provide a pulse signal output capable of interfacing to
most monitoring and control systems, such as a PLC or DCS. The cable output from the
flow-meter can also be wired to instruments such as totalisers, rate totalisers or batch
controllers. These instruments are available from your Flomec distributor and can be
purchased with monitoring and control output options including 4-20mA, scaled pulse,
flow-rate alarms and batch control logic (preset metering).
1.1 Operating Principle
Oval Gear flow-meters are positive displacement devices where the passage of liquid
causes two oval geared rotors to rotate within a precision measuring chamber. Each
rotation of the Oval rotors will transmit 4 identical volumes of liquid from the meter inlet to
outlet (as shown in the diagram below); providing electronic pulses via magnetic sensors to
a digital instrument.

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1.2 Specifications
1.2.1 Small Capacity Models
Model
EGM004
EGM006
EGM008
Nominal Size
4mm / 1/8”
6mm / 1/4”
8mm / 3/8”
Nominal 3cP Flow range (L/hr)
1 ~ 36
2 ~ 100
15 ~ 550
Nominal 3cP Flow range (GPH)
0.26 ~ 9.5
0.5 ~ 26.4
4 ~ 145
Accuracy ( liquids ≥ 3cP)
± 1% of reading
Additional error for
Uncalibrated Meters
± 1% of reading
Repeatability (liquids ≥ 3cP)
Typically ± 0.03%
Temperature Rating
-15oC ~ +80oC (5oF ~ +176oF)
Pressure Ratings –Bar (PSI)
Aluminium
34 (500)
34 (500)
34 (500)
Stainless Steel
55 (800)
55 (800)
34 (500)
Flow Ranges for Various Viscosity Liquids - L/hr (GPH)
1cP 1
2 ~ 24
(0.53 ~ 6.3)
5 ~ 80
(1.3 ~ 21.1)
18 ~ 440
(4.8 ~ 116.2)
7cP
0.5~36
(0.13 ~ 9.5)
1 ~ 100
(0.26 ~ 26.4)
15 ~ 550
(4.0 ~ 145.3)
200cP
0.4~36
(0.11 ~ 9.5)
0.7 ~ 100
(0.19 ~ 26.4)
6 ~ 550
(1.6 ~ 145.3)
500cP
0.25~27
(0.07 ~ 7.1)
0.5 ~ 100
(0.13 ~ 26.4)
2 ~ 550
(0.53 ~ 145.3)
1000cP 2
0.12~16
(0.03 ~ 4.2)
0.3 ~ 45
(0.08 ~ 11.9)
1.5 ~ 360
(0.40 ~ 95.1)
Nominal Output Pulse Resolution –Pulses/Litre (Pulses/USGallon)
Standard Hall Effect
2800 (10600)
1060 (4012)
720 (2725)
Fuel Consumption Option
2800 (10600)
1060 (4012)
180 (681)
Minimum Filtration
75 micron (200 mesh) 3
Notes:
1. When operating on 1cP liquids the meters may be used up to the nominal (3cP) maximum flow rate rating
for intermittent periods only.
2. For applications above 500cP the maximum flowrate must be reduced according to the table above, for
applications above 1000cP the maximum flow rate must be reduced further in order to limit the maximum
pressure drop across the meter to below 1Bar (14.5psi). Consult the manufacturer if you are unsure.
3. Filtration requirements are for soft particles only; hard particles of any size are not acceptable.

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1.2.2Medium Capacity Models
Model
EGM015
EGM020
Nominal Size
15mm / 1/2”
20mm / 3/4”
Nominal 3cP Flow range (L/min)
1 ~ 40
3 ~ 80
Nominal 3cP Flow range (GPM)
0.3 ~ 10.6
0.8 ~ 21.1
Accuracy ( liquids ≥ 3cP)
± 0.5% of reading
Additional error for
Uncalibrated Meters
± 0.5% of reading
Repeatability (liquids ≥ 3cP)
Typically ± 0.03%
Temperature Rating
-15oC ~ +80oC (5oF ~ +176oF)
Pressure Ratings –Bar (PSI)
Aluminium
20 (290)
20 (290)
Stainless Steel
20 (290)
20 (290)
Flow Ranges for Various Viscosity Liquids - L/min (GPM)
1cP 1
1.5 ~ 32
(0.40 ~ 8.45)
5 ~ 64
(1.32 ~ 16.9)
7cP
0.5 ~ 40
(0.13 ~ 10.57)
2 ~ 80
(0.53 ~ 21.1)
200cP
0.4 ~ 40
(0.11 ~ 10.57)
1.8 ~ 80
(0.48 ~ 21.1)
500cP
0.3 ~ 40
(0.08 ~ 10.57)
1.5 ~ 80
(0.40 ~ 21.1)
1000cP 2
0.2 ~ 25
(0.05 ~ 6.60)
1 ~ 50
(0.26 ~ 13.2)
Nominal Output Pulse Resolution –Pulses/Litre (Pulses/USGallon)
Standard Hall Effect
170 (644)
105 (398)
Fuel Consumption Option
42.5 (161)
26.3 (99.5)
Minimum Filtration
75 micron (200 mesh) 3
Notes:
4. When operating on 1cP liquids the meters may be used up to the nominal (3cP) maximum flow rate rating
for intermittent periods only.
5. For applications above 500cP the maximum flowrate must be reduced according to the table above, for
applications above 1000cP the maximum flow rate must be reduced further in order to limit the maximum
pressure drop across the meter to below 1Bar (14.5psi). Consult the manufacturer if you are unsure.
6. Filtration requirements are for soft particles only; hard particles of any size are not acceptable.

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1.2.3 Electrical Specifications
Standard Pulse Output
Hall Effect Output
Output Type
NPN Open Collector
Voltage Range
5 ~ 24VDC (±0.5%)
Current Draw
20mA Maximum
Switching Current
10mA Maximum
Fuel Consumption Option
Hall Effect Output
Output Type
NPN Open Collector
Voltage Range
5 ~ 24VDC
Current Draw
20mA Maximum
Switching Current
10mA Maximum
RTD Output
Sensor Type
Platinum Resistance
According to IEC 60751
Nominal
Resistance
100 Ohm
Temperature
Coefficient
3850 ppm/K
Tolerance Class
F0.3 / Class B
Maximum
Measurement
Current
0.1mA ~ 1.0mA

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2. Pre-Installation
All flow-meters are inspected and calibrated prior to shipment, and are sent out in perfect
condition. Should damage be present on receipt of the product please inspect the delivery
packaging for visible mishandling and contact the parcel service / freight forwarder. Flow-
meters are shipped with protective plugs/caps in all openings; these should be maintained
until the product is ready for installation, failure to do so will expose the precision internal
components of the flow-meter to dust and dirt and may cause damage of the flow-meter.
Prior to installing your flow-meter it is recommended that the following application
conditions are checked:
That the fluid being metered is compatible with the materials of construction of the
flow-meter: Aluminium meters are generally only suitable for fuels and oils, if you
have purchased an Aluminium meter for a water based liquid please check suitability
with your Flomec distributor prior to installation
That the system pressure and temperature are within the limits shown on the flow-
meter name-plate.
That the maximum and minimum flow rates are within the specification of the flow-
meter
That the liquid being metered is free of any particles
That the meter is not exposed to temperatures (system or ambient) that may cause
the liquid to flash (convert to a gas) within the flow-meter
If measuring a high viscosity liquid, confirm that the maximum flow-rate of the flow-
meter has been appropriately de-rated so as to limit the maximum pressure drop
across the meter to 100kPa (1bar, 14.5psi). For viscosities less than 1000cp please
see the spec table in section 1.2
Please note that all factory calibrated flow-meters are tested with Castrol
Diesel Calibration Fluid 4113 immediately prior to shipment, and while every
effort is taken to adequately drain the product prior to packaging and
shipment, some residual oil will be present. Please take the appropriate
precautions that would be taken with any mineral oil, and should an MSDS be
required this is available from the manufacturer or via an internet search.
CAUTION

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2.1 Pre-Installation Testing
Testing of a flow-meter before installation is a common source of mistakes that has the
possibility to permanently damage your flow-meter. Tests should always be carried out in
conditions that match the operation parameters that the meter was selected for; most
importantly flow rate and chemical compatibility. Testing of Aluminium meters on water is
not recommended however it is possible without damage so long as all of the water is
removed from the meter following the test. Aluminium meters tested on water should
always be dried after testing, as stagnant water will cause corrosion of Aluminium.
Any flow-meter which is individually calibrated at the factory will be factory marked with
its respective K-Factor (Pulses/Litre or Pulses/Gallon); there is typically no reason to carry
out any pre-installation accuracy testing on these meters. For those users that wish to
carry out pre-installation testing or calibration of a non-calibrated model, it is important
that the test procedure be carried out scientifically or the results of the test will be
meaningless. Particular cases that may benefit from field calibration or accuracy testing are
those with liquids of very low viscosity (<1cP).
For any field calibration of your flow-meter it is important to consider the accuracy of
your calibration procedure, and of your volume standard. Calibration of your flow-meter
using a volume standard of unknown accuracy will produce poor results; a bucket or
Intermediate Bulk Container (IBC) should never be used as a volume standard. Ideally your
volume standard must be large enough to contain at least 2 minutes of flow at the nominal
system flow rate, and the flow-meter should not be operated below its minimum flow-rate
at any point during the calibration run.
Never test an Oval Gear flow-meter on compressed air; to do so will cause
dry running and over speeding of bearings, leading to premature wear and
failure.
CAUTION

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3. Mechanical Installation
It is strongly advised that before installation of your meter, you thoroughly read and
understand the information presented in this section, as failure to install your meter
according to the guidelines below may cause permanent damage to your meter, or a
reduction in system performance and reliability. Any damage to your flow-meter as a result
of incorrect installation or start-up procedure will not be covered by the manufacturer’s
warranty.
Fluid entering the meter must remain a liquid at all times; avoid solidification or gelling of
the metered medium. If meters are to be trace heated or jacketed in any way the maximum
temperature rating of the meter must not be exceeded.
If hydraulic shock or pressure surges of any kind are possible, the system upstream of the
meter must be fitted with a surge suppressor or pressure relief valve to protect the meter
from damage. High frequency flow pulsations will create erroneous readings and in
extreme cases may damage the meter; most pulsations are removed with the installation of
a suitable pulsation dampener.
3.1 Installation Orientation
Almost all positive displacement flowmeters have a specific mounting orientation that
must be adhered to in order to limit the loads on the rotor thrust bearings. Failure to
mount your Oval Gear flow-meter in the correct orientation (as shown in the diagrams
below) will cause the weight of the rotors to bear down on the thrust bearings, and on the
floor of the measuring chamber. The short term effects of incorrect mounting orientation
will be a loss in accuracy, with long term effects ranging from reduced lifespan to complete
failure of the flowmeter. Damage caused by an incorrect mounting orientation is not
covered by warranty.
UP

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Liquid can flow in a horizontal direction, or a vertical direction, but in each case the rotor
shafts must be in a horizontal plane. The direction of flow is not important, as the output is
non-directional; for any installations where pulses from reverse flow are not desired a
check valve (or other suitable non-return valve) should be used.
3.2 Piping Construction
Pipe work design and construction is a factor that can have a significant impact on the
operational performance of your flow-meter. A correctly designed piping system will
protect the flow-meter from damage from pipe-stress, will limit external effects on system
accuracy, and will provide a system that is easy and economical to maintain.
For best results follow the following guidelines:
Avoid installing a flow-meter on the suction side of a pump; where this is unavoidable
ensure there is a large positive suction head.
It is preferred to install the flow-meter upstream of a flow control or shut-off valve, as
the back pressure provided by the valve will be beneficial to system accuracy.
Do not operate a flow-meter directly discharging to atmosphere.
Piping should be designed so that the flow-meter is full of liquid at all times, this is
achieved by designing the inlet and outlet piping for the flow-meter to be lower than
all surrounding piping.
For vertical installations the liquid should travel from bottom to top, i.e. it should rise
vertically through the flow-meter. This will ensure that the flow-meter remains full of
liquid, and will stop air entrapment in the meter.
Piping surrounding your flow-meter should be well supported, preferably at a point
close to where the piping joins to the flow-meter; long sections of unsupported piping
will cause pipe stress on the flow-meter which may effect accuracy. It is generally
acceptable to hang your meter on the piping, provided the piping is well supported,
however it is never acceptable to mount your flow-meter securely and use the meter
as the only mounting point for long lengths of piping.
If your flow-meter is installed in a section of piping that can be completely isolated
between two shutoff valves, and that section of isolated piping is at risk of thermal
expansion (e.g. is located outdoors in the sun) it will be necessary to install pressure
relief valves, or thermal expansion joints.

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The best piping designs provide a bypass line, as shown in the following diagram,
which allows isolation of the flow-meter and associated strainer from the main process
line. The benefits of installing a bypass line are that your system can be purged before
start-up, to remove any foreign particles or air slugs that would cause serious damage
to your meter. Other benefits of this piping design are that maintenance and repairs
on your flow-meter and strainer can be carried out quickly and economically without
interrupting critical processes. Smaller installations, or non-critical processes may not
see a benefit from installing a bypass line.
3.3 Filtration / Straining
All liquid products have the chance of solid particles being present, especially in any new
installations, or in installations where the liquid is open to atmosphere at any point. Solid
particles may come from dust settling on an unsealed storage tank, wear particles from
upstream mechanical devices such as pumps or mixers, or even large metal particles from
cutting or welding on new or modified installations.
It is always advisable to fit the inlet side of any Oval Gear flow-meter directly to a strainer
of appropriate pipe size and mesh size to suit the liquid being measured. The minimum
mesh size as shown in the specifications section of this manual should be adhered to where
ever possible. When metering medium or high viscosity fluids it may be necessary to use a
strainer one pipe size larger than the flow-meter nominal size, in order to limit the pressure
drop across the strainer basket and maintain strainer efficiency.
3.4 Pipe Connections
When installing a flow-meter it is important that no upstream pipe join between the
flow-meter and the strainer are sealed using PTFE sealing tape. Lose pieces of PTFE tape
are common causes of failure in new meter installations due to the tendency to wrap
around the rotating components inside the meter. It is recommended that the sealing of
pipe joins should be done with a sealing paste (such as Loctite® 565 thread sealant paste),
however care must be taken to avoid excess sealant entering the flowmeter when
screwing in fittings.
Strainer
Flowmeter
Isolation valve
Isolation valve
By-pass valve

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3.5 Fuel Consumption Measurement
When purchased with the ‘Fuel Consumption’ option the EGM Series flow meters are well
suited to the measurement of fuel consumption on injected diesel or petrol/gasoline
combustion engines. The flowmeters should be purchased and installed in pairs; with
flowmeter ‘A’ installed prior to the inlet side of the fuel rail or injection pump, and flowmeter
‘B’ installed immediately after the fuel rail or injection pump – as per the diagram below.
Electrical installation in a fuel consumption system is detailed in section 4.4.3
Before installing your flowmeters it should be confirmed that they are suitable for the
flowrate of the primary fuel pump, which will be significantly higher than the fuel consumption
rate reported in the engine datasheet. As an example, an average 500HP marine diesel engine
may have an approximate consumption of around 50L/Hr of diesel fuel but will have a fuel
system flowrate of around 300L/Hr –check your meter specifications against the higher fuel
system flowrate before installing.
Fuel consumption flowmeters should be installed according to the requirements in other
sections of this manual; the inlet side of Flowmeter ‘A’ should be fitted with a strainer or filter
of appropriate size (see specification table, section 1.2) - your existing fuel filter may be
suitable if the filtration level meets the flowmeter specification. If your existing fuel filter is
engine-mounted, it may be more practical to install the flowmeter prior to the fuel filter and fit
a y-strainer to the inlet of flowmeter ‘A’.
Due to the vibrations caused by a running engine it is recommended to avoid mounting the
flowmeters directly to the engine. To ensure complete filling of the flowmeters it is best to
mount them at a location which is physically lower than surrounding fuel lines.
Flowmeter B
Injected
Combustion
Engine
Flowmeter A
Strainer

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4. Electrical Installation
Two types of output are available on an EGM Series Oval Gear flow-meter; the standard
output is a single NPN Hall Effect sensor, providing a square wave frequency output signal
which is linearly proportional to volumetric flow.
The optional Fuel Consumption model provides a similar NPN Hall Effect sensor output
combined with a Platinum Resistance Thermometer output.The Fuel Consumption model
has a specific magnetic sensor design which is tailored to produce accurate measurements
on fuel injected combustion engines, which are typically prone to flow pulsations. In
addition to the volume measurement, the Fuel Consumption option also provides a
temperature measurement of the liquid inside the flowmeter; this allows for temperature
compensation of liquid volumes between the inlet and outlet of an engine’s fuel system.
4.1 Wiring
EGM Series flowmeters are equipped with quality shielded instrument cable; 3 twisted
pairs of stranded wire (7/0.25mm), Mylar tape screened with a stranded (7/0.25mm) drain
wire. Wire ends are provided stripped and tinned from the factory, ready to be terminated
at the input terminals of a receiving instrument or control system.
For installations which require a longer length of cable than is provided from the factory
(2 metres), an in-line connector kit and extra lengths of cable can be purchased from your
Flomec distributor. Alternatively any good quality in-line connector with a suitable number
of pins and a suitable IP rating can be used. For standard pulse output flow meters a 4 pin
connector is advised (3 wires for the sensor, 1 wire for the cable drain), and for meters
fitted with a PT100 a 7 pin connector is advised. All extended wiring should use high quality
instrument cable; twisted pair low capacitance shielded instrument cable is recommended.
The cable drain or screen should be terminated on a DC common or a specifically assigned
shield terminal at the readout instrument end; in order to protect the signal from mutual
inductive interference.
The cable should not be run in a common conduit, or parallel with, power cables or high
inductive load carrying cables, as power surges may induce erroneous noise transients onto
the transmitted pulse signal or cause damage to the electronics. Run all instrument cables
in their own separate conduit; where instrument cables must cross high power cables be
sure that the cables intersect at 90 degrees in order to limit induced interference.

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Do not install a meter in close proximity to any sources of strong magnetic fields, such as
high power electric motors or solenoids, as these may affect the magnetic sensors within
the meter. Likewise, it is recommended that instrument cables are not located close to
sources of strong magnetic or electric fields due to the risk of induced interference in the
cables.
4.2 Hall Effect Outputs
The NPN Hall Effect is a high resolution solid state 3 wire device which provides an un-
sourced, open collector, NPN transistor output. The term unsourced means that no voltage
is applied to the output from within the flow-meter. The output of the Hall Effect must be
pulled to a ‘high’ state by an external voltage between 5-24VDC, this is achieved by fitting a
pull-up resistor between the signal output (white wire) and the voltage supply (red wire).
The pull up resistor ties the open collector output to the available DC voltage level,
providing a square wave pulse output, which alternates between ground potential and the
DC voltage available at the signal wire.
The NPN Hall Effect output is a reliable output type, producing a consistent output
irrespective of supply voltage variations below the maximum voltage limit, temperature
variations, or mechanical shock. The service life of the Hall Effect output is theoretically
infinite, so long as it is protected from high energy voltage spikes. Hall Effect outputs are
protected against reverse polarity, and against low energy voltage spikes; however they are
not protected against constant over-voltage above the maximum limit of 24V (±5%).
Many secondary flow instruments are fitted with an integral pull-up resistor, but if
connecting the Hall Effect output to an electronic device that does not contain an integral
pull-up resistor, one MUST be fitted by the installer. The pull-up resistor is connected
between the signal wire (white) and the +VDC wire (red); recommended pull-up resistor
value is 10kOhm, 2.4kOhm is the minimum value.
It is NOT recommended to combine any inductive loads on the same voltage supply as your
flow-meter, as these components are commonly sources of high frequency interference
that may affect the quality of the Hall Effect output signal. Another concern to do with
inductive loads on a common voltage source is the potential for voltage spikes well in
excess of the 24VDC limit of the Hall Effect sensors.

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4.3 RTD Output (PT100)
The RTD (Resistance Temperature Detector) is a 3-wire 100 Ohm Platinum Resistance
thermometer (PT100), built into the meter cap of the flow meter. The RTD is directly
mounted to the PCB of the flowmeter, which is then encapsulated into the meter cap using
a thermally conductive epoxy potting compound, ensuring quick thermal transfer from the
process liquid to the temperature sensor.
The RTD has standardised characteristics according to IEC 60751, with a temperature
coefficient of +3850 ppm/K (between 0oC and 100oC), and is a tolerance class B (F0.3)
device.
The RTD may be used in either a 2-wire or a 3-wire system; each have their own benefits,
however for best accuracy it is recommended that a 3-wire system is used. When using the
RTD in a 3-wire system the third wire is used to calculate the average resistance of the
cable between the readout instrument and the RTD, this allows the readout instrument to
subtract the resistance of the cable from the resistance of the RTD itself –giving a much
more accurate measurement. The downsides of a 3-wire system is a small amount of extra
cost.
For installations which cannot accept the extra cost of the additional wire in the cabling
plus the more expensive receiving instrument, a 2-wire system can provide a reasonably
accurate temperature measurement when cable lengths are less than 10 metres.
To avoid self-heating of the temperature sensor, the measurement current should be kept
between 0.1mA ~ 1mA; this will limit the self-heating effect to less than 0.1oC and will
maintain the accuracy of the device. Self-heating errors are proportional to the DC power at
the RTD and are approximately equal to 0.8oC / mW.

17
4.4 Wiring Diagrams
4.4.1 Standard Pulse Output Board
*A Pull-Up Resistor must be installed between the signal and +VDC connections
on the receiving instrument –unless the instrument has an integral pull-up*
4.4.2 Fuel Consumption Option
*A Pull-Up Resistor must be installed between the signal and +VDC connections
on the receiving instrument –unless the instrument has an integral pull-up*
*For installations using 2-wire RTD/PT100 connections, use only the yellow +
green wires.

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4.4.3 Fuel Consumption Wiring with F127 Flow Computer
* Regulated DC supply should be in the range of 8-30 Volts DC. When powering
the flow computer from a vehicle charging system a DC-DC converter is
recommended to protect the system from voltage spikes.
4.5 Meter Calibration Factor (K-Factor, Scale Factor)
Each flow-meter is individually calibrated and is marked with the number of pulses per
unit volume (e.g. pulses/Litre) which is characteristic to the particular meter. Nominal
values are shown in the specification section of this manual. For meters ordered un-
calibrated the nominal values shown in the specification section should be used; additional
error should be expected for meters when using nominal K-factors on un-calibrated meters,
this information can be found in the Specification Table (section 1.2). Field calibration of an
un-calibrated meter removes this error; if you are measuring a high viscosity liquid, field
calibration may actually achieve better levels of accuracy than can be obtained from the
factory diesel calibration.

19
5. Commissioning
The most common cause of damage to Oval Gear meters is improper start-up procedure
after an installation or piping modification. New or modified piping is generally full of large
volumes of air, and possibility contains foreign matter. If your piping has been designed
carefully as outlined in this manual, it will be an easy task to prepare your system for safe
commissioning of your flow-meter.
The newly installed meter must NOT be run until the piping is completely flushed of
foreign materials. The most common foreign matter that is present in new or modified
piping is; welding slag, grinding dust, sealing tape/compound, and surface rust. If your
piping has been designed with a bypass line it will be easy to isolate your meter from the
remainder of the system in order to flush out the majority of the piping. If you have not
installed a bypass line around the meter, the best solution is to replace the meter with a
spool-piece for the duration of the flushing procedure; if this is not practical then the rotors
must be removed from the meter prior to flushing.
The other critical concern when commissioning a meter is the presence of air slugs; this is
also a concern for any systems that have been shut down for long periods of time. Do not
start up your system for the first time by opening all valves and turning on the pump, or
by quickly opening up the supply valve from a gravity feed tank; it is essential that the
system is first purged of air. Large volumes of air contained in the piping will be
compressed very quickly between the oncoming liquid and the stationary flow-meter rotors
and will spin the rotors at speeds many times that of their maximum rating which can very
often completely destroy the meter.
To safely start a meter for the first time, and avoid any failure from air slugs, the best
procedure is to eliminate the majority of the air volume in your piping system using the
bypass line described earlier. After bleeding the majority of the air through the bypass line,
the remainder of the air can be slowly passed through the meter by gently opening the flow
control valve downstream of the meter. If a bypass line has not been incorporated into your
system, and no alternative exists for bleeding air upstream of the meter, then the entire air
volume of your piping will need to be bled very slowly through the downstream valve.
Following the start-up procedure, and during the period of initial operation, it is
recommended that the inlet strainer on your meter be inspected regularly, and cleaned if
necessary, as it is possible that not all foreign material will be completely removed from
your system during the initial flushing.

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6. Maintenance
Adhering to the installation instructions is the most important requirement to ensure that
your Oval Gear meter provides the maximum level of operational performance. Oval Gear
meters are a mechanical device, and so will be subject to some wear and tear over their
operational life, except under ideal circumstances. The amount of normal wear that the
meter will experience will be very dependent on the operational conditions such as; flow
rate, temperature, cleanliness of the liquid, lubricity of the liquid, and the amount of
continuous duty required of the meter.
In order to maximise the operational availability of your meter, and reduce system
downtime, a periodic maintenance and inspection regime should be used. Frequency of
maintenance depends on the operational conditions of the meter and the criticality of the
system; it is the user’s responsibility to determine inspection frequency however the
manufacturer can provide guidance.
For any installations that require in-situ cleaning (CIP); it is important that the cleaning or
flushing procedures do not produce operating conditions that are outside of the acceptable
flow rate, pressure, or temperature ratings of the meter. Chemical compatibility of cleaning
solutions should be checked against the materials of construction of the meter.
Before undertaking meter maintenance ensure the following:
Associated alarm(s) or control output(s) are isolated so not to affect the process
Voltage supply is isolated from the meter
Liquid supply to the meter is closed off
The meter is depressurised and liquid drained from the meter / pipeline