AMETEK Ranarex Portable Gas Gravitometer for Specific Gravity

The AMETEK Ranarex Gas Gravitometer is a portable mechanical instrument that reads the specific gravity of a gas stream directly on a dual-scale dial. It has no glass cells or electronic sensing parts: the measurement comes from comparing the torque produced by the sample gas with the torque produced by reference air, so the reading responds instantly and does not rely on a chemical reaction or on gas diffusion.

Seven Star LLC supplies the Ranarex from Muscat for natural gas, refinery and fuel gas duties where a simple, bench- or wall-mounted specific gravity check is needed.

How the Ranarex measures specific gravity

The chassis forms two cylindrical, gas-tight measuring chambers, each with its own inlet and outlet. In each chamber an impeller and an impulse wheel with axial vanes are fitted. An electric motor and drive belt turn both impellers at the same speed and in the same direction, drawing the gas sample into the upper chamber and reference air into the lower chamber. The spinning gas and air strike the vanes of the impulse wheels and create torques proportional to the density of the gas and of the air. Two external measuring wheels carry a flexible tape wrapped in the crossed direction, so the two torques act as opposing forces. The measuring system divides the gas torque by the air torque, which is the density of the gas divided by the density of the air, that is, the specific gravity.

AMETEK states a track record of more than 60 years and an estimated 30,000 installations. Jeweled pivots and permanently lubricated ball bearings keep wear low, and the design eliminates span drift so calibration stays permanent. The portable version needs no elaborate setup: it can stand on the floor or a bench, hang from a wall, and run from a standard AC supply or from a 12 V vehicle battery through a DC-AC inverter.

• Meets ASTM D1070
• Instantaneous response with no reaction or diffusion time
• Installation needs only piping or tubing and electrical power
• Silica gel ambient air reference dryer and built-in sample flowmeter

Technical specifications

Applications and what to confirm before ordering

AMETEK lists natural gas custody transfer, pipelines and blending, natural gas liquids and LPG separation, refining recycle gases and catalytic reformers, combustion analysis, fuel gas systems, hydrogen in ammonia manufacturing, coke oven, water and producer gases, petroleum off-gases and sewage treatment. Key markets are natural gas, refining, chemical and petrochemical, and steel and heat treating.

Confirm the supply voltage and frequency (115 VAC 60 Hz or 230 VAC 50 Hz), the expected specific gravity of the sample against the two dial ranges, sample pressure against the 20 psig limit, and that the gas is compatible with the wetted mechanical parts, particularly for wet or corrosive streams. Send the sample composition when requesting a quotation.

Documents and quotation

To request a quotation for the Ranarex gravitometer, send Seven Star LLC the full model or order code, quantity, and any nameplate data from an existing unit that is being replaced or matched. Our Muscat team checks the request against the manufacturer document, which can be downloaded from this page, and replies with a formal quotation. Prices, stock and lead times are confirmed per inquiry.

Related reading on this site: the gas analyzer systems category, and AMETEK 930 sulfur pit H2S analyzer.