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Technical Description



PNEUMATIC GAS PREHEATER RMG 901 Application, Characteristics, Technical Data

Application • For control gas-preheating, for example, in order to prevent the formation of ice and hydrate • Suitable for small output capacities • Gas for vortex tube (Ranque-Hilsch effect) and control gas-preheating are separate circuits. This allows the usage of two different gases • Fully independent due to the fact that no external energy is needed for heating


Characteristics • Simple design • Easy to integrate into already existing gas pressure regulating stations • Easy pipe-installation • Vortex tube without any moving internal parts • Entire circuitry is integrated into the safety system according to DVGW worksheet G 491 • For proper functioning, a supercritical pressure ratio is necessary for the vortex tube inflow • No need for external energy • No energy costs

ATTENTION! The assured function of control-gas-heating by the pneumatic gas preheater RMG 901 with control valve can only be guaranteed in combination with indirect working gas pressure regulators of the RMG delivery program. TECHNICAL DATA Max. per. operating pressure PS

Thermal output

KG-values of the components based on natural gas

100 bar For an optimum thermal output, a supercritical pressure ratio pd / pu ≤ 0,5 is necessary (see diagram on page 3)! Control valve

≈ 22,5 m3/h

RMG 901

≈ 4,0 m3/h

with ρn = 0,83 kg/m3

(Pressure drop to the control gas of the regulator negligible)

Max. temperature of housing at room temperature

approx. 60 °C

Max. flow

Qn = 30 m3/h

Control gas outlet temperature

> 15 °C

Gas connections



hot surface

Screw connections without brazing acc. to DIN 2353 External pipe diameter 10 and 12 mm approx. 3 kg CE-sign not necessary

CE-sign acc. to PED

SEP design (sound engineering practice) acc. to article 3 paragraph 3 of the Pressure Equipmant Directiv (PED)

PNEUMATIC GAS PREHEATER RMG 901 Design and Operation

The vortex tube preheater features two circuits: the primary circuit for heat generation by the vortex tube effect and the secondary circuit for the regulation gas flow to be heated. The upstream control valve is designed to automatically block the gas flow of the primary circuit to the vortex tube gas preheater if there is no gas discharge. Then the gas pressure regulating station goes into the reseat pressure pf mode. If there is no gas discharge in stations, it is possible to omit the control valve, under consideration of the maximum possible gas flow through the RMG 901. In this case, if it is necessary to block the gas flow, this is only carried out manually using the ball valve. This takes place via the pressure differential measurement membrane which is exerted to loading pressure and outlet pressure in the control valve. If there is no gas discharge, the differential pressure is also zero; the control valve closes automatically via the spring tension. Here, the reseat pressure still corresponds to the value specified by the pilot of the gas pressure regulator. For testing purposes or for general deactivation of the RMG 901 preheating, a ball valve is located upstream. When the station is put into operation, the preheater heats up after a short time through the vortex tube effect, and thus the control gas towards the regulator. After the preheater, the hot gas and cold gas flow is merged together again and funneled in the outlet line after the gas pressure regulator. No external energy is needed for preheating whatsoever.

Application area of RMG 901 against the pressure ratio pd / pu

RMG 901 limited application 100 90

Inlet pressure pu in bar


RMG 901 applicable

70 60 50 40 30 20

RMG 901 inapplicable

10 0









Outlet pressure pd in bar







PNEUMATIC GAS PREHEATER RMG 901 Design and Operation

RMG 408 with RMG 901 and pilot RMG 610

Control valve


Outlet pressure measuring line

Loading pressure line

Measuring line

Pilot RMG 610

Bleed line Loading pressure line

Ball valve

RMG 901 Inlet pressure line

Filter RMG 905

Inlet pressure Outlet pressure Loading pressure Load limiting pressure Atmosphere

Actuator RMG 408

PNEUMATIC GAS PREHEATER RMG 901 Design and Operation

RMG 502 with RMG 901 and pilot RMG 630

Control valve Ball valve

RMG 901 Start-up valve Throttling valve Filter RMG 905 Pilot RMG 630 Inlet pressure line Load limiting stage

Loading pressure line Measuring line Control stage Bleed line

Actuator RMG 502


PNEUMATIC GAS PREHEATER RMG 901 Design and Operation

History of the vortex tube The process of splitting gas into two separate flows of hot and cold gases, through the use of a tangential tube inflow, was invented by French physicist G. J. Ranque in 1931. On the inner flow vortex, temperatures of up to -50 °C occurred (cold gas flow). On the outer vortex ring flow, a temperature increase of up to +100 °C was determined (hot gas flow). The German physicist R. Hilsch carried out the first systematic investigations of this effect from 1945 to 1948.


Today, this effect is referred to as the “Ranque-Hilsch vortex tube effect” in recognition of the contributions of both physicists. Even today, fundamental physical questions regarding the function of a vortex tube are still open, despite all efforts. Currently vortex tubes are still largely designed empirically with experimental values. A vortex tube can be optimized both for the hot gas flow as well as for the cold gas flow. When using the Ranque-Hilsch vortex tube for preheating control gases (for example, in the case of pneumatic regulators) and small gas quantities, no external energy is needed whatsoever. This also means there are no energy costs!

PNEUMATIC GAS PREHEATER RMG 901 Dimensions and Connections



Ă˜ 60



7 75








all dimensions in mm






RMG is your competent partner along the entire chain ranging from the exploration to the supply of final consumers. Our reliable products and systems offer to you full control within the range of regulating and measuring technology.

Furthermore we plan and build plants according to your requirements and offer to you reliable and modern solutions also in station automation. Ask us - we look forward to your challenges.


GERMANY RMG REGEL + MESSTECHNIK GMBH Osterholzstraße 45 34123 Kassel, Germany Phone +49 (0)561. 5007-0 Fax +49 (0)561. 5007-107

WÄGA WÄRME-GASTECHNIK GMBH Osterholzstraße 45 34123 Kassel, Germany Phone +49 (0)561. 5007-0 Fax +49 (0)561. 5007-207

RMG MESSTECHNIK GMBH Otto-Hahn-Straße 5 35510 Butzbach, Germany Phone +49 (0)6033. 897-0 Fax +49 (0)6033. 897-130 Works Ebersberg: - Software development Anzinger Straße 5 85560 Ebersberg, Germany Phone +49 (0)8092. 20 97-0 Fax +49 (0)8092. 20 97-10

RMG-GASELAN REGEL + MESSTECHNIK GMBH Julius-Pintsch-Ring 3 15517 Fürstenwalde, Germany Phone +49 (0)3361. 356-60 Fax +49 (0)3361. 356-836



BRYAN DONKIN RMG GAS CONTROLS LTD. Enterprise Drive, Holmewood Chesterfield S42 5UZ, England Phone +44. 12 46 501-501 Fax +44. 12 46 501-500

BRYAN DONKIN RMG CANADA LTD. 50 Clarke Street South, Woodstock Ontario N4S 7Y5, Canada Phone +1. 519 53 98 531 Fax +1. 519 53 73 339

POLAND GAZOMET SP. Z O.O. ul. Sarnowska 2 63-900 Rawicz, Poland Phone +48. 65 546 24 01 Fax +48. 65 546 24 08

We reserve the right for technical changes

Edition 03/2007

Pneumatic gas preheater RMG 901

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