ROTARY PISTON GAS METER
IRM INFINITY
ROTARY PISTON GAS METER IRM
M-IRM-12
NATIONAL
ACCREDITATION
OF CERTIFICATION
BODIES
2
GENERAL
The Instromet IRM Infinity rotary piston gas meter is a positive displacement type meter which, by means of a counter,
registers the quantity of gas in units of volume at the prevailing measurement pressure and temperature (operating m3).
The Instromet rotary meter fully complies with the requirements of many international and national standards regar-
ding design and accuracy and is approved to EEC and Dutch specifications by the Nederlands Meetinstituut (NMI). Instro-
met BV is certified in accordance with ISO 9001.
THE IRM INFINITY ROTARY PISTON GAS METER
Stress-free and low-noise replaceable meas-
urement module embedded in flexible seals.
Temperature sensor points
Oil filling
(under index)
Hinged type plate
Oil drain
Low frequency
connections
Oil sight gauge
Pressure Point
Pressure Point
OPERATION
The Instromet IRM Infinity meter is a high accuracy positive displacement meter
which is insensitive to changes in the relative density of the gas to be measured.
Measurement takes place by means of two figure eight rotors (synchronized by
gears) which rotate in a chamber of known volume. Four times per revolution, a
fixed unit of volume is displaced (see hatched
areaindrawing). Therevolutionsof
the
rotors are transmitted to the counter by means of amagnetic coupling. The
design, combined with the precision-finishing of both the rotors and the measu-
ring chamber, ensures a
continuous seal without
actual contact between
these components. This
minimizes the possibility of
gas passing through the
chamber without being
measured.
Main-measurement chamber and rotors
The Instromet IRM Infinity meter is
suitable for the measurement of all
non-corrosive gases, such as natural
gas, propane, butane, air, nitrogen,
dry hydrogen, ethylene, etc. The IRM
Infinity meter can be used for meas-
urement where a high accuracy is
requiredoverawideoperating range
APPLICATIONS
3
CONSTRUCTION AND RANGE
The range or turn down of the Instromet Infinity meter
is far in excess of any other type or design of rotary
meter due to the following features: Instromet uses a
modular type design, which permits the use of a
separate measurement module inserted in the pressure
housing. The measurement module is pressure
balanced and in thermal equilibrium with
the gas. Neither the pressure nor the temperature
of either the gas or the ambient atmosphere
causes any mechanical stress that could affect meter
performance. External forces transferred by the piping
on to the meter body are not transferred to the
measurement module. These features permit
precision machining of the measurement parts,
guaranteeing an extremely low-flow capability with
repeatable high pressure measurement and atmospheric
calibration curves. The pressure balanced design ensures that there are no dimensional changes in the measurement ele-
ment itself and therefore no internal passage of unmeasured gas. By using this modular design, replacement of the
measurement module (pre-calibrated) can be carried out in less than 10 minutes while the meter body remains installed.
This simplifies maintenance.
RESONANCE
OR OSCILLATION
All rotary type meters are subject to
resonance or oscillation at certain
flow points. This oscillation is caused
by a variable discharge of the flow
chamber and may occur at specific
flow rates or revolutions of the
meter.
The unique design of the Instromet
IRM infinity meter, whereby the
space around the flow module func-
tions as a dampener, makes the
meter substantially less prone to
oscillation. This, together with the
wide operating range, make the IRM
an ideal meter for low and high pres-
sure transfer provers.
REPLACEMENT OF
INDUSTRIAL DIAPHRAGM
METERS BY INSTROMET
ROTARY METERS
Because of its exceptional measure-
ment range, Instromet rotary gas
meters are frequently installed to
replace large industrial diaphragm
meters. Not only do they meet all
range requirements but they also
take up less space and thus reduce
installation costs.
NOISE AND
NOISE TRANSFER
The Instromet IRM Infinity measure-
ment module is embedded in flexible
seals in the meter body. Therefore a
large part of the noise created by the
rotors and gas displacement is not
transferred to the meter body and
connecting piping system.
This results in a meter which is
quieter than any other rotary meter.
INCREASING RANGE IN
METERING
By using an Instromet IRM Infinity
meter in combination with a range
extender in a regulating station, the
meter size can be reduced depending
on the available inlet pressure.
Piping, valves and fittings can be
reduced and ranges of over 1:1000
can be achieved. The range extender
provides effective restriction of the
flow rate, eliminating the risk of
overspeeding.
LUBRICATION SYSTEM
Another example of the user-friend-
liness of the IRM rotary meter is the
integration of the lubricating system.
Whereas existing rotary meter
designs require oil changes to be per-
formed at each side of the meter
(variety of drainage/filling points),
the Instromet IRM rotary meter
features a single drainage and filling
plug. The ideally chosen position of
the drainage and filling point ena-
bles the meter to be used in both the
vertical and horizontal flow direc-
tions. All meters with a compact
index or universal index have a lubri-
cation fill and sight glass on the
front.
OPTIONAL FLOW
DIRECTION
The IRM Infinity rotary meter with a
universal index can be installed for
either left, right, top or bottom flow
entry, without changes to the meter
or calibration curve, thus reducing
inventory requirements.
On request both calibration curves
can be provided.
Type IRM-A FLANGED WITH MULTI-
INDEX
Pressure rating : PN 16
Housing material : Aluminium
Max. oper. pressure : 16 Bar
Flanged Connection: PN 16
(Din 2633)
ANSI 125/150
Measurement
range : G16 - G250
(25 to 400m3/h)
Counter mechanism: Multi index
AUTOMATIC INTERNAL
BY-PASS OPTION
Instromet Rotary meters offer an
extremely large range and therefore
are widely used in applications and
installations where gas consumption
may vary from litres per hour to
many cubic metres per hour. All
rotary meters of all manufacturers
may malfunction and block the gas
flow due to external causes, such as
FOD (Foreign Object Damage) or by
installation or application errors. To
guarantee the gas flow, Instromet
offers, as an option, a built-in auto-
matic by-pass which opens at the
occurrence of such a blockage or at a
specified maximum pressure differen-
tial. This option is particularly recom-
mended when an uninterrupted gas
supply is essential (hospitals, factories
etc). The opening of the by-pass valve
can be recorded and signalled by a
pressure differential switch, incorpo-
rating a contact for recording or
memory function.
4
MATERIALS
Magnetic coupling : Ferroxdure
Meter housing : Aluminium / Ductile / Steel
Meter housing cover : Aluminium / Ductile / Steel
Rotor housing : Aluminium, Hard anodized
Rotors : Aluminium, Hard anodized
End caps of rotor housing : Aluminium, Hard anodized
Rotor shafts : Stainless steel
Counter mechanism head : Aluminium
COATINGS
Meter housing : Synthetic paint, yellow, RAL1004
Meter housing cover : Synthetic paint, yellow, RAL1004
Counter mechanism head : Synthetic paint, white, RAL9001
Flange connection : DIN 2633 ND10/ND16 - ANSI 125 / 150 / 300 / 600
Diameters : 11/2”, 2”, 3” and 4” (40, 50, 80 and 100 mm)
Seals : VITON/NBR
Measuring range : See table
Accuracy : Per approval specifications - generally ± 2% Qmin
to 0.2 Qmax and < 0,5% - 0.2 Qmax to Qmax
Reproducibility : Better than 0.1%
Gas Temperature Range : -20° to +60°
Max. oper. pressure : Aluminium: 16 bar / Ductile: 16 bar
For low and medium pressure applications Instromet uses either extruded alumini-
um bodies or ductile iron. The aluminium is manufactured to DIN 1748. The ductile
iron used, meets a number of standards and is specifically approved for higher
temperatures. Instromet has also developed carbon steel body versions of the
rotary meter for high pressure applications to 100 bar. Specifications and other
information about this unique meter are available on request.
TECHNICAL SPECIFICATIONS
Special High pressure IRM with inte-
grated by-pass and pressure diffe-
rential gauge.
Universal index*
- Counter mechanism with LF
impulse transmitter
(either flow direction)
Compact index *
- Counter mechanism with LF
impulse transmitter
Multi index*
- Counter mechanism with LF or HF
impulse transmitter
5
TYPICAL CALIBRATION CURVE
MEASUREMENT RANGES / PULSE DATA
The above HF pulse data are approximate values.
** Optional: the LF pulse values can be multiplied by 2, 5 or 10
LOW
Q-MAX. RANGE FREQUENCY HF PULSER
TYPE/UNIT RATED CAPACITY ERROR STARTRATE STOPRATE PULSES m3
RATING m3/h < 10%
at ±1% at ±2% ** 1 pulse/m3Pulse Frequency
per m3/Hz
G 10 16 1:50 1:100 0.04 (1:400) 0,02 (1:650) 0,014 (1:1500) 10
G 16 25 1:80 1:125 0.05 (1:500) 0,03 (1:830) 0,015 (1:1670) 10 8554.68 59
G 25 40 1:100 1:130 0,07 (1:570) 0,060 (1:670) 0,040 (1:1000) 10 5344.75 59
G 40 65 1:120 1:150 0,100 (1:650) 0,060 (1:1080) 0,050 (1:1620) 10 3332.56 60
G 65 100 1:130 1:170 0,150 (1:670) 0,075 (1:1330) 0,050 (1:2000) 10 2141.00 59
G 100 160 1:150 1:250 0,150 (1:1070) 0,075 (1:2130) 0,050 (1:3200) 1 1689.50 75
G 160 250 1:200 1:280 0,200 (1:1250) 0,100 (1:2500) 0,060 (1:4170) 1 802.73 56
G 250 400 1:200 1:300 0,200 (1:2000) 0,200 (1:4000) 0,060 (1:6670) 1 505.74 56
COUNTER MECHANISM MODELS
PRESSURE LOSS
The calibration curve for the G25 IRM Infinity.
Flow rate in %
* HF Impulse transmitter optional
6
DIMENSIONS AND WEIGHTS
IRM-A G16 .... G100
Compact / universal index
C /U= Compact Index / Universal Index
M = Multi Index
N = Number of bolts
W = Weight (Kg)
Dimensions in mm
IRM-A G16 .... G100
Multi index
7
INSTALLATION AND
OPERATING INSTRUCTIONS
1. The gas should be clean and dry.
It is recommended that a 5 µ dust
filter be placed upstream the
meter.
2. Check the flow direction.
3. The oil reservoir may only be fil-
led after installation of the
meter. The meter is supplied with
a container of the recommended
oil.
4. Fill the oil reservoir until the oil
level reaches the middle of the
sight glass (meter must be
depressurized).
5. The meter must not be exposed
to vibration.
6. Start-up should be performed
with care, i.e. pressurize the sys-
tem gradually, The flow rate
should never exceed the maxi-
mum meter flow rate.
7 IRM meters are suitable for out-
door installation provided they
are protected against direct cli-
matic effects.
8 The temperature of the gas
should remain within the range
of -20°C to +60°C. The ambient
temperature should preferably
not vary from these values by
more than 5°C upwards or down-
wards.
9. When installing a gauge and/or
pressure recorder for custody
transfer, the location of the pres-
sure reference point Pr should be
carefully noted.
IMPULSE TRANSMITTERS
LF: All IRM Infinity meters are fitted with two low-frequency impulse trans-
mitters in the counter mechanism.
HF: Additionally, a sensor can be fitted on the rotor shaft, which provides a
stable high-frequency signal.
MAINTENANCE
The Instromet IRM rotary meter requires an oil change once every 5 to 10 years,
depending on the service conditions. Checks of the oil level should be per-
formed using the sight glass on the meter. An accuracy indication can be ob-
tained with a simple differential pressure measurement technique.
IRM meters which are fitted with the universal index or the compact index have
the oil level gauge and filler cap on the same end as the index, thus permitting
back-to-wall installation. Those meters with the multi index have the gauge
and filler cap on the opposite end.
HOW TO ORDER
To supply the best meter for your application, please provide us with the follow-
ing information:
1. Capacity in reference volume units and reference conditions.
2. Operating pressure: minimum and maximum
3. Service temperature: minimum and maximum
4. Ambient temperature: minimum and maximum
5. Type of gas
6. DIN or ANSI flanges, or other type of connection
7. Counter mechanism model (compact, multi, universal)
8. Meter type
9. Preferred flow direction.
10. Accessories: Electronic Volume Corrector, LF/HF impulse transmitter, etc.
OTHER OPTIONS
The measured volume can be cor-
rected for temperature alone or for
temperature and pressure by means
of an Instromet electronic volume
corrector, which is pulse driven from
the rotary meter. One or two ther-
mal wells for fitting of temperature
probes can be provided. For high
resolution can be equipped with a
high-frequency output signal in addi-
tion to the standard low frequency
output pulse from the index. G-25 IRM Infinity with Instromet volume corrector
pr
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