Gilflo ILVA flowmeters - for steam, liquids and gases
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Gilflo ILVA flowmeters
for steam, liquids and gases
The Gilflo in-line variable area (ILVA) flowmeter ...
is a revolutionary development of the well established family of Gilflo flowmeters
that has been used in industrial flowmetering applications for more than 30 years.
Using the same unique operating principle but incorporating a number of significant
design changes, the Gilflo ILVA flowmeter is perfectly suited for use with most industrial
fluids including steam and gases. A comprehensive range of associated sensors and
electronic instrumentation is available to compliment the Gilflo ILVA flowmeter
range and make it one of the most adaptable flowmeters available.
Why install flowmeters?
The main justifications for installing flowmeters in any industrial plant are:
n Product quality: By providing management information, they enable a plant to be operated
at peak efficiency thus ensuring product quality is maintained in the most cost effective way.
n Direct cost control: They can be used to cost raw materials or energy sources
(such as compressed air) directly.
How the Gilflo ILVA flowmeter works
In common with other differential pressure flowmeters such as
orifice plates and venturi meters, the Gilflo ILVA flowmeter primary
element uses the theorem for the conservation of energy in fluid
flow through a pipe.
It operates on the well established spring loaded variable area
(SLVA) principle where the area of an annular orifice is
continuously varied by a moving cone. A centrally positioned cone
is free to move axially against the resistance of a precision
compression spring. This produces a variable differential pressure
across the annular orifice which is sensed by a transmitter Dp
connected to integral tappings on the flowmeter body. The
pressure difference can then be used to derive an instantaneous
rate of flow based on Bernoulli’s Theorem.
The unique design of the Gilflo ILVA flowmeter greatly expands the capabilities of the differential pressure
flow measurement. The key to the unique performance of the Gilflo ILVA flowmeter lies in the design of the
orifice and cone to minimise upstream velocity profile effects and at the same time provide an exceptionally
high turndown flowmeter based on practically achievable line velocities.
Installation benefits D Gilflo ILVA
The correct installation of any type of flowmeter is of prime
importance if the manufacturers claims for accuracy and
repeatability are to be achieved in practice. All types of flowmeter
require a certain number of straight, uninterrupted lengths of meter
size pipework upstream and downstream of the point of installation. 6D 3D
In real life, there are often space constraints that severely restrict where and how a flowmeter can be installed. It
is therefore very important to look carefully at where the flowmeter is to be fitted as early as possible. The unique
wafer design of the Gilflo ILVA flowmeter means that its installed length is much shorter than almost any other
flowmeter. A Gilflo ILVA flowmeter can often be fitted into lines which were never designed to accept flowmeters.
Gilflo ILVA flowmeter 6 diameters
up to
Turbine 20 diameters
up to
Vortex 30 diameters
up to
Orifice plate
30 diameters
0 10 20 30
2 Number of upstream diameters of straight pipe
The importance of turndown
DN150 Gilflo ILVA flowmeter 5 bar g saturated steam
Vortex meter
Benefit of large turndown at low flows
Gilflo ILVA flowmeter
0.6 1 2 2.8 3
Minimum velocity m/s
To ensure that the flow information gathered is accurate Turndown ratios with flow velocities limited to 35 m / s
whatever the process conditions or demand, it is essential
that a flowmeter is capable of meeting its specification over Gilflo ILVA flowmeter 100:1
the full operating range from low standing or weekend loads,
right up to the maximum demand of the process. As actual
Turbine typically 10:1
demands are often unknown or may vary widely, a flowmeter
should have the largest turndown possible based on
practical flow conditions. Great care should be taken that Vortex up to 15:1 depending on operating conditions
claims for turndown are based on realistic flow velocities.
For instance, steam systems should be sized on a maximum Orifice 4:1
flow velocity of about 35 m / s ... higher velocities will
possibly cause erosion and noise problems in the system. 0 20 40 60 80 100
1 000 2 000 This graph shows a typical
Cumulative error kg
Flowrate kg / h
Actual flowrate demand curve for a distributed
Cumulative error 1 700
steam system with a high
750 1 500 start-up load and variable
demand through the day. An
orifice plate meter with a
500 1 000
4:1 turndown is sized on the
peak load of 1 000 kg / h. Any
250 500 flowrates below 250 kg / h are
Threshold at Orifice plate 'lost' or, at best recorded with
4:1 turndown a significant error. In this case
0 0 1 700 kg have been 'lost'.
0 1 2 3 4 5 6 7 8
The Gilflo ILVA flowmeter, with
Hours elapsed
its 100:1 turndown eliminates
Flowrate below minimum of 250 kg / h (i.e. 1 000 kg / h ÷ 4) this type or error.
Density
compensation 1 000 10
3 500
It is rare for the pressure in Actual flowrate
800 8 3 000
a steam system to remain
Cumulative error kg
Actual system pressure
2 500
Pressure bar g
absolutely constant. Unless
Flowrate kg/ h
this variation is taken into 600 6
2 000
account, flow measurement
errors will occur. The automatic 400 4 1 500
density compensation options
1 000
completely eliminate these 200 2
errors and allow accurate 500
metering whatever the steam Cumulative error
0 0 0
pressure. This is shown in the 0 1 2 3 4 5 6 7 8
adjacent diagram. Hours elapsed
In the example above, a simple non-compensated flowmeter is set for 6 bar g. The actual pressure in the system varies through the
day and unless this is allowed for, by the end of the day, very significant errors can arise. This is typical of many steam systems.
3Gilflo ILVA flowmeters ...
proven technology in a new package.
Thirty years experience and over 10 000 installations worldwide has firmly
established the technology that gives Gilflo flowmeters their unequalled
turndown and ultra compact installation. Now the Gilflo ILVA
flowmeters uses this wealth of experience in a wafer
design to give even lower cost of ownership.
Designed and supported by Spirax Sarco’s
worldwide supported, the Gilflo ILVA
flowmeter is the logical choice.
Range availability
n Sizes DN50 (2")
to DN200 (8")
n All stainless steel
316L body construction
n Pressure rating to match
flange specifications
n Temperatures up to 450°C
Applications
n Cost metering for Flow
energy management direction
n Custody transfer
n Process and
control applications
n Boiler load control
Commonly
metered fluids
n Saturated steam
n Superheated steam
n Condensate
n Natural gas
n Nitrogen
n Carbon dioxide
n Compressed air
n Ethylene
n Fuel oil
4User benefits
• Suitable for most
industrial fluids.
• Excellent turndown,
up to 100:1.
• High pipeline unit accuracy,
±1% of reading.
• Ultra compact installation,
requires only six pipe
diameters upstream and
All stainless steel three downstream.
construction.
• Wafer design for easy
installation.
Alignment webs for easy
installation. • No expensive line size
changes required to achieve
low flow performance.
Precision cone.
• Intrinsically safe for use in
hazardous areas.
• Reliability proven over
Wafer design fits between 30 years experience.
customer flanges.
• Designed and manufactured
by Spirax Sarco -
a ISO 9001 : 2000
Over-range stop prevents approved company.
damage from surges or
excessive flows.
Precision heavy duty
nickel cobalt alloy
spring operates up to
450°C without creep.
Pressure tappings built
into the flowmeter body
for easy installation.
Gilflo calibration rig, Spirax Sarco, Cheltenham, England
5Gilflo ILVA flowmeters ...
system configurations and associated equipment
EL2230 temperature transmitter Gilflo ILVA n M240G (steam) and M250G (gas) flow computers
provide complete information on flow, pressure
and temperature.
n Full density compensation.
n Linearisation of Gilflo signal.
F50C isolation
valves n Wall or panel mounting.
EL2600 n Bright, easy to read display.
pressure M610
transmitter differential n Alarm facilities for fluid flow, pressure and
pressure temperature.
transmitter
n 4 independent timers.
n Analogue, pulse and EIA232C outputs available
M200 series flow computer as standard.
Gilflo ILVA n M640 steam mass flow transmitter provides
density compensated 4 - 20 mA output.
n Linearisation of Gilflo signal.
n Ideal for applications where density
compensation is essential.
F50C isolation
valves n Suitable for use up to 74 bar g saturated steam.
n HART® 5.2 in-built.
M640
Steam mass n Optional local display.
flow transmitter
n Intrinsically safe pipeline unit
and mass flow transmitter.
M750 display unit
Gilflo ILVA n M750 display unit provides local display of
total flow and rate of flow.
n Suitable for steam and
most industrial fluids and gases.
F50C isolation n Ideal for applications where
valves
fluid density is constant.
M610 n User configurable.
differential pressure
transmitter n Linearisation of Gilflo signal.
n Retransmission options of rate and / or
total flow available.
n Bright, easy to read display.
M750 display unit
n Panel mounting as standard.
Note:
The illustrations above are schematic only.
Refer to Installation and Maintenance Instructions for further details.
6Calibration of Gilflo ILVA flowmeters
All Gilflo ILVA flowmeters are calibrated on a high accuracy flow facility at Spirax Sarco’s manufacturing plant
in Cheltenham, England. Designed and built by Spirax Sarco engineers in conjunction with UK National
Engineering Laboratories, it ensures that every flowmeter meets the highest possible standard of accuracy.
Some basic features of the flow facility are:
n Facility size capability: DN50 to DN300.
n Reference methods: gravimetric and transfer standard electromagnetic meters.
n Flow capacity: up to 19 000 litres/min water.
n Pipework: all 316L stainless steel with upstream and downstream pipework straight runs in excess of recommended lengths.
n Flowmeter location: clamping arrangements ensure flowmeters are concentric to pipework to ensure accurate calibration.
n Fully automatic data collection: archiving of all flow data electronically for future reference / recalibration.
n Calibration documentation: full calibration documentation is available with every flowmeter.
Sizing and selection of a Gilflo ILVA flowmeter
It is important to select the correct size of Gilflo ILVA flowmeter for a particular application. First principles can be
used as follows, determine the equivalent water flowrate (litres/min) based on the maximum anticipated actual flow,
then select the Gilflo ILVA best suited to the application using the tables below. Alternatively consult Spirax Sarco.
Equivalent water flowrate QE
Mass flow units Volumetric units Where:
QE = Equivalent water flowrate (litres/min)
qm qm = Mass flowrate (kg/min)
Liquids QE = QE = QLÖ SG QL = Maximum liquid flowrate (litres/min)
Ö SG
QS = Maximum gas flowrate at standard conditions (litres/min)
QF = Maximum gas flowrate at actual flow conditions (litres/min)
Gases and SG = Specific gravity
steam QE = qm 1 000 QE = QF DF DS = Density of gas at standard conditions (kg /m3)
actual flow Ö DF Ö 1 000 DF = Density of gas at actual flow conditions (kg /m3)
conditions PS = Standard pressure = 1.013 bar a
= 1.033 kg / cm2 a
Gases qm = 14.7 psi a
QE = QE = QS DS x PS x TF PF = Actual flow pressure in same absolute units as PS
standard DS PF TS
x x Ö 1 000 PF TS TS = Standard temperature (K) = °C + 273
conditions Ö1 000 PS TF TF = Actual flow temperature (K) = °C + 273
Using the value of QE as determined above, select the correct Gilflo flowmeter from the table below:
Table of QE
Maximum QE Maximum DP Example:
Flowmeter type Determine which Gilflo pipeline unit is required to measure the
litres / minute Wg
flow of compressed air when:
DN50 149 200 1: Estimated maximum rate of flow = 500 s m³/h at 7 bar g and 20°C
DN80 585 200 Note: Standard conditions = 1.013 bar a, 0°C giving a standard
DN100 1 800 200 density of 1.29 kg / m³ DS P T
DN150 2 900 200 2: Calculate QE from QE = QS x S x F
Ö 1000 PF TS
DN200 5 700 200
QE = (500 x 16.667) x 1.29 1.013 293
x x
From the table, it can be seen that a DN50 Gilflo ILVA flowmeter would Ö 1000 8.013 273
be suitable for this application. Note: 1 m³ / h = 16.667 litres/ min. QE = 110 litres / min.
Sizing the Gilflo ILVA flowmeter for saturated steam - capacities kg / h
Steam pressure bar g 1 3 5 7 10 12 15 20 25 30 40
Maximum flow 300 416 503 577 671 727 804 918 1 020 1 113 1 283
DN50
Minimum flow 3 4 5 6 7 7 8 9 10 11 13
Maximum flow 1 179 1 632 1 976 2 264 2 635 2 855 3 156 3 603 4 003 4 371 5 039
DN80
Minimum flow 12 16 20 23 26 29 32 36 40 44 50
Maximum flow 3 629 5 023 6 080 6 967 8 108 8 784 9 709 11 085 12 317 13 449 15 505
DN100
Minimum flow 36 50 61 70 81 88 97 111 123 134 155
Maximum flow 5 847 8 092 9 795 11 224 13 062 14 152 15 643 17 859 19 843 21 667 24 980
DN150
Minimum flow 58 81 98 112 131 142 156 179 198 217 250
Maximum flow 11 492 15 905 19 252 22 061 25 674 27 816 30 746 35 101 39 002 45 587 49 098
DN200
Minimum flow 115 159 193 221 257 278 307 351 390 426 491
Note: Maximum flowrates are calculated at a differential pressure across the Gilflo ILVA pipeline unit of 498 mbar (200" H20).
Minimum measurable flowrate is 1% of maximum.
7Gilflo spring design
The design and manufacture of the spring in the Gilflo ILVA flowmeter is fundamental to its accuracy and long term performance.
n Made from 'aerospace' alloy Inconel X750 which is widely used in jet engine turbine components due to its exceptional high
temperature performance.
n During manufacture, all springs are age hardened at 650°C for 4 hours.
n All springs are 'hot set' at 460°C after manufacture to eliminate any possibility of relaxation at high temperatures.
n Design stress levels range from 11% to 30% UTS ... most springs are designed to stress levels of around 60%.
n In service, all Gilflo ILVA flowmeters incorporate over-range stops to prevent over stressing the spring in overload conditions.
n Many thousands of installations have proved the integrity of the design and manufacture of the spring.
Specification
Operating principle Spring loaded variable area with differential pressure output proportional to rate of flow.
Limiting conditions To ANSI 600 (carbon steel) pressure / temperature envelope.
Sizes available DN50, DN80, DN100, DN150 and DN200
EN 1092 PN16, PN25, PN40
BS 10 Table H
Flange specifications ANSI B 16.5 Class 150, 300, 600
JIS 20
KS 20
Materials of construction Body and internals: Stainless steel 316L
Spring: Inconel X750
Installation Normally horizontal. For vertical (flow downwards) applications, consult Spirax Sarco.
When used in conjunction with an M200 series flow computer or M750 display unit or M640 steam
Accuracy mass flow transmitter, pipeline unit accuracy is better than ± 1% of actual flow from 5% to 100% of
maximum rated flow. For flows from 1% to 5% of maximum rated flow, the pipeline unit accuracy
will be better than ± 0.1% FSD.
Repeatability Better than 0.25%.
Unrecovered pressure drop Less than 200 inches water gauge (498 millibar) at maximum flowrate.
Dimensions / Weights (approximate in mm and kg) E
Size A B C D E Weight Note: Pressure tappings
are threaded ¼" NPT.
DN50 35.0 63 130 103 17.5 2.0 (2 off located at 180°)
DN80 45.0 78 160 138 22.5 3.9
DN100 60.5 103 208 162 37.5 8.3
DN150 75.0 134 300 218 37.5 14.2
DN200 85.0 161 360 273 42.5 23.6
D
In addition to the ILVA range, Spirax Sarco can supply
Gilflo flowmeters for special requirements in sizes from DN50 to
DN400. These are of flanged, pressure vessel type construction
and can be manufactured to meet most international standards
construction and inspection. Please consult Spirax Sarco for
details.
A
B
Some of the products may not be available in certain markets. C
Spirax-Sarco Limited, Charlton House,
Cheltenham, Gloucestershire, GL53 8ER UK.
Tel: +44 (0)1242 521361 Fax: +44 (0)1242 573342
E-mail: Enquiries@SpiraxSarco.com
Internet: www.SpiraxSarco.com
© Copyright 2003 Spirax Sarco is a registered trademark of Spirax-Sarco Limited
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