SERVING THE GAS INDUSTRY WORLDWIDE
Technical Product Information
ROTARY RO OTARY DISP DISPLACEMENT PLA ACE EMENTT M METER ETER RMG 132-A
RMG Messtechnik GmbH
ROTARY DISPLACEMENT METER RMG 132-A Application, method of operation, testing, maintenance
Testing / Gas meter calibration
• RMG 132-A rotary displacement meter for volumetric gas measurement in gas distribution stations and in domestic, administrative and industrial buildings. • Suitable for use with all non-corrosive gaseous media, such as natural gas, propane, butane, nitrogen, air, etc. • For vertical or horizontal installation in both flow directions. • No inlet or outlet pipes are required for operation. • Can also be used in the case of intermittent gas withdrawal.
The rotary displacement meters correspond to DVGW, PTB and EC regulations and other international and national regulations of various countries. In our staterecognized testing laboratory for gas measuring devices, each rotary displacement meter is tested in operational condition and checked for compliance with the error range. It is then provided with an oﬃcial seal which identifies it as being approved for custody transfer metering.
Method of operation
The quality details resulting from the strength and leak tests are documented in accordance with national and international standards.
The rotary displacement meter is a gas meter which measures the volume of gas and operates on the displacement principle. It records the gas volume at actual line conditions (i.e. volume at measurement conditions) which has flowed through the gas meter. A downstream volume corrector can be used to convert this volume into the volume at base conditions. The rotary displacement meter consists of the actual measuring element and a totalizer to display the volume at measurement conditions. When the gas decreases, there is a pressure drop between the meter inlet and outlet which produces a torque at the two rotary pistons. As soon as this torque exceeds the holding torque of the rotary pistons, the pistons start to rotate. The rotation of the pistons is forcecontrolled by precision gears located outside of the measuring chamber. In the further course of the rotation of the pistons, the two sections of the measuring chamber of the rotary displacement meter are periodically filled and evacuated. There is a non-contact seal between the two measuring chamber sections which is achieved by minimum gaps between the rotary pistons themselves and between the rotary pistons and the casing. The rotational movement of the pistons is transferred through a magnetic coupling to the pressureless compartment of the totalizer where the rotations are added and then displayed on a digital index as volume (m3, ft3). The totalizer is installed rotatably and can be adjusted to the relevant position for installation and direction of flow of the gas meter. LF and HF pulsers can be fitted in the totalizer. They generate an electric volume pulse which is further processed by appropriate supplementary equipment. The rotary displacement meter starts to operate at a pressure drop of less than 0.1 mbar and a flow rate of less than < 1/1000 Qmax.
Installation and maintenance The rotary displacement meter is to be installed in the pipeline with minimum stress using appropriate seals and screws according to standards. No base is required for the gas meter. During installation, the rotary displacement meter is to be aligned using a spirit level, so that the piston axes are in a horizontal position.This ensures uniform lubrication of the gear parts in the front and rear covers. For troublefree operation of the gas meter, only filter-purified gases with a solids grain size of less than 50 μm are permissible. It is recommended that a filter or at least a start-up screen be installed. The gas meter is supplied without oil. As soon as the unpressurized gas meter has been installed in the pipeline, the cover compartments are to be filled with oil.This has to be done gradually in order to avoid filling beyond the sight-glass area. When commissioning the gas meter, pressure shocks are to be avoided. The process should be performed slowly. Maintenance of the gas meter is limited to an oil-level check which is to be performed approximately once a year. For this purpose, the rotary pistons must be at rest. If the oil level falls below the centre mark of the sight glass, oil has to be topped up. We would recommend using the oil types Shell Tellus oil 10 or BP Energol HLP 10 or a comparable oil with a kinematic viscosity of 10 mm2/s at 40°C. The totalizer is completely maintenance-free. The gas meter can also be used in outdoor installations if an appropriate protection against the weather is provided. For special information about installation and maintenance, see the Operating and Maintenance Instructions 132.20.
ROTARY DISPLACEMENT METER RMG 132-A Capacity data CAPACITY DATA Qmin Size
Measuring range 1:65
3 G 100
Error of measurement %
NOTE: Standard - measuring range 1:50
* Approx. values; see the pulser plate for the precise pulse value.
+2 +1 0 -1 G
Flow rate m3/h
Average error curve (Qt - as a function of the measuring range)
Pressure loss mbar
G Flow rate m3/h
Average pressure loss curve
(Average pressure loss in mbar at Qmax)
ROTARY DISPLACEMENT METER RMG 132-A Dimensions and weights, taps DIMENSIONS AND WEIGHTS Size
G 40 G 65
Flanges with threaded holes DIN 2501
ANSI B 16.5
PN16 8x M16 PN25
NOTE: The overall lengths greyed out have rings on both sides.
1 - Totalizer,
2 - Measuring element,
3 - Pressure tap,
4 - Temperature tap,
5 - Pulser connection,
6 - Oil-level gauge
The temperature taps are required for installing thermowells for resistance thermometers. They are located on the inlet and outlet flanges of the gas meter. Note: Standard – without thermowells; threaded holes sealed with screw plugs.
Pressure taps are required to determine the pressure at measurement conditions when a volume corrector is connected or for diﬀerential pressure measurement via the gas meter. The gas meter has one pressure tap on each of the inlet and outlet flanges.
ROTARY DISPLACEMENT METER RMG 132-A Technical data RMG 132-A Material
G 40 – G 65 – G 100 – G160
PN 16, ANSI 150
Installation position / Direction of flow
Horizontal or vertical / universal
No inlet or outlet section required
Operating temperature range
-40°C to +60°C
Adapted to DIN EN 12480 - PTB approval up to 1 :160
- EC approval
- other international approvals Degree of protection
Steel, hardened and ground
Type of connection
Flanges with threaded holes DIN 2501
ANSI B 16.5 RF
PN 16 – DIN 2501
ANSI150 – ANSI B 16.5 RF
1: 50 (standard) up to 1 : 160 (option) < 2% at Qmin
< 1% at Qmax (factory-provided: 0.5%)
See table on page 3
For a short time up to 1.25 Qmax
Rate of pressure variations
< 0.5 bar/s
Pressure and temperature taps are located in the inlet and outlet of the meter casing.
1x LF(reed), further LF or HF (NAMUR) pulsers as option
On the front (standard), on both sides as option - Double totalizer as standard - 8-digit index in m3 (standard) or ft3 (option)
- Optical start-up display - Can be universally adapted to the direction of flow; a representative of the weights and measures oﬃce need not be present on this occasion.
TEMPERATURE TAPS Rotary displacement meter
Thread M14 x1.5
1x inlet 1x outlet
Seal of threaded hole
Screw fitting with sealing cone for pipes with dia. Ø6
Screw plug 1/4 NPT
Al / PN16 G 1/2 *
G 1/2 *
* on request
Installation variants for thermowells
ROTARY DISPLACEMENT METER RMG 132-A Flow variants
The position for installation or direction of flow can subsequently be changed by simply turning the totalizer or the totalizer cap. For further details, see the Operating and Maintenance Instructions 132.20.
The totalizer can optionally be fitted with one or more pulse transmitters. Signals are picked up through a lateral plug.
Types LF - reed switch, polarity-independent - operating voltage U = 5-24 V DC - switching current, max. I = 10 mA
- NAMUR slot-type initiator, polarity to be observed - operating voltage U = 8 V DC - current input approx. 3 mA
- without pulse transmitter - 1 x LF (standard) - 1 x LF, 1 x HF - 1 x LF, 2 x HF - 2 x LF - 2 x LF, 1 x HF
ROTARY DISPLACEMENT METER RMG 132-A Device designation, accessories
Ordering information (example) Device designation:
G40; G65; G100; G160
DN 50 (2˝ ) DN 80 (3˝ ) DN 100 (4˝)
Pressure rating/ Flanged ends
Overall length E
1:20; 1:50; 1:65; 1:80; 1:100; 1:160
State in which supplied Position for installation / Direction of flow
SU - perpendicurlarly downwards (standard, if not indicated otherwise) WR - horizontally to the right SO - perpendicurlarly upwards WL - horizontally to the left
1x LF, 1x LF 1x HF, 1x LF 2x HF, 2x LF, 2x LF, 1x HF
0; 1; 2* * Type of installation: 1x inlet, 1x outlet 2x inlet
Accessories • Thermowell - Integral thread M14x1.5 G 1/2 – on request Connection of the temperature sensor G1/4 - Integral thread 3/4 NPT Connection of temperature sensor on request
• Start-up screen (mesh size 0.4 mm) • Volume corrector • Fastening bracket for Volume corrector • Three-way check valve
State in which supplied - Position for installation / Direction of flow
Pressure rating / Flanged ends
RMG 132-A - Al - G65 - DN50 - PN16 - 171 - 1:80 - SU - 2x NF - 2x (inlet)
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Mercury Instruments LLC 3940 Virginia Avenue Cincinnati, Ohio 45227 Phone +1 513 272-1111 Fax +1 513 272-0211
We reserve the right for technical changes
Rotary Displacement Meter RMG 132-A