Most of the aircraft are powered by aviation gasoline, or “avgas.” The main challenge in handling avgas is keeping it clean, with any impurities capable of damaging sensitive airplane engines. Therefore, the hydrant-based fuel-pumping systems that are common at most airports, large or small, require the use of fuelfilter strainers and separators.

As these strainers and separators fill up with impurities, the differential pressure across them will get higher. This can cause variations in the fueling system’s pumping pressure, which can typically range from 60 to 125 psi (4.14 to 8.62 bar).

Thanks to their unique self-adjusting vane design, which does not require a lubricating fluid, positive displacement (PD) sliding vane pumps will not be affected by changes in differential pressure while being able to maintain the proper flow rate.

Blackmer has developed the perfect solution with its GNX Series Sliding Vane Pump. The GNX model – which is part of the Blackmer Iron Line of PD sliding vane pumps – is the market’s only alignment-free, reduced-speed PD pump.

The GNX pumps, which are suitable for both mobile and stationary applications, have the features of the Blackmer legacy GX Series pump, but take performance to the next level via the incorporation of a commercial-grade, single-stage gearbox. This gearbox is positioned between the pump and motor and held in place by a permanent dowelled connection that creates a structural link between the high-speed and low-speed sides of the pumping system.

The result is a pump that will not need to be realigned either at installation or after a maintenance procedure. GNX pumps are available in 2-, 2.5-, 3- and 4-inch sizes and have 90-degree porting orientation (180 degrees for the GNXH model). A composite baseplate provides unmatched surface flatness, which reduces installation costs and operational vibration.


Other Blackmer models that will perform well in avgas applications include the X, MLX and HXL Series pumps. These high-capacity pump models are capable of producing high flow rates, which make them a better choice for aircraft with larger fuel tanks. Additionally, BV Series Bypass Valves can be used to further mitigate differential-pressure concerns. They feature a chamber that fills with liquid when the valve opens. This hydraulic “cushion” prevents the valve from slamming shut, which minimizes chatter, cavitation and valve-seat wear.


Metrans Makina is the only authorized Blackmer distributor and service provider in Turkey.

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