Elster RABO Rotary Gas Meter DN32 to DN150

Compact rotary gas meter with a wide measuring range and no inlet section

The Elster RABO is a positive-displacement rotary gas meter from the Honeywell Elster range for nominal sizes DN32 to DN150 (1.25 in to 6 in) and meter sizes G16 to G400. Two impellers shaped like a figure eight turn in one housing, are coupled by synchronizing gears and push a defined gas volume from inlet to outlet with every rotation, without touching each other. Their revolutions reach the mechanical index through a reducing gear and a magnetic coupler.

Because the principle measures operating volume directly, the reading does not depend on the inlet flow profile, so the RABO suits compact metering systems that have no straight inlet section. Honeywell lists measuring ranges of up to 1:200, approval for custody transfer, and suitability for natural gas, filtered non-corrosive gases and 100% hydrogen in custody-transfer and non-custody-transfer use. RABO combines features of earlier Elster-Instromet rotary meters and adds a maintenance-free version that runs without oil lubrication.

Technical specifications

Sizes and housing options

Each G size is offered in more than one nominal diameter: G16 to G65 in DN32, DN40 and DN50, G100 in DN50 and DN80, G160 and G250 in DN80 and DN100, and G400 in DN100 and DN150. The datasheet gives Qmin for ratios between 1:200 and 1:20 by meter size, for the oil-lubricated and the maintenance-free version separately, so the usable range depends on which version is ordered.

In the aluminium housing dimension A is 171 mm up to G100 and 241 mm from G160, and dimension F grows from 286 mm to 510 mm on the G400. Dimensions A to F, flange bolt circles and weights are printed for aluminium and spheroidal cast iron, including the shorter EBL 150 variant.

Index, pulse outputs and corrector mounting

The standard S1 index head is IP67, carries an 8-digit mechanical counter and can be rotated by 350 degrees without breaking seals, so the same meter serves horizontal and vertical pipework. Low-frequency pulsers plug on without opening the index and can be retrofitted later. An electronic volume conversion device can be mounted on the meter; the datasheet notes that height C changes when thermowells, pressure taps, the HF pulser or a corrector such as the EK280 are fitted.

Documents and quotation

State the gas and its filtration, flow range, operating pressure, nominal size, housing material, oil-lubricated or maintenance-free version, index and pulse configuration, hazardous-area zone and any hydrogen share. The datasheet prints a maximum operating pressure of 20 bar under technical data while the sample type plate shows 16 bar and the flanges are PN16 or Class 150, so confirm the permitted pressure of the exact version with the manufacturer. The datasheet edition is July 2025.

The attached Honeywell datasheet covers the RABO measuring ranges, pulse values, pressure loss, index options and dimensions. Seven Star LLC, an independent supplier in Muscat, quotes the meter against the configuration above. Related items are listed under Flowmeters, and for flow conversion see the Elster gas-net F1 flow computer.