Bi-directional spinner Flowmeter


This QL series probe measures impeller rotation caused by fluid flow in the borehole. It uses a magnetically coupled pick-up which drives a low friction, high resolution encoder located inside the lower pressure housing. The encoder produces 256 pulses per shaft rotation. It has quadrature  sensing electronics that instantaneously detect flow direction changes.

The QL40 SFM is a bottom sub, and can be combined with other logging tools in the QL (Quick Link) product line or operated as a stand alone tool. Weight bars with centralizers are recommended to improve log response and repeatability in large boreholes or low flow environments.

Temperature – Pressure

0-70°C (32-158°F)
200 bar (2900 psi)

Diameter – Length

40 mm (1.6”) excluding cage
0,9 m (35,4”)


3.2 kg (7 lbs)


60mm diameter pitch impeller / 75 mm diameter cage.

75mm diameter pitch impeller / 100mm diameter cage.

Spinner speed in cps up and down.


Manufactured by Geotomographie GmbH

Technical Details

Generated wave types: SV
Signal frequencies: Up to 500 Hz (depending on geology and borehole distance)
Operational depth: Up to 100 m
Source length: 1015 mm
Source weight: 6 kg
Cable weight per metre: 377 g
Borehole diameter: 75-100 mm (or larger if spacers are used)
Clamping system: Infatable bladder
Depth indicator: Cable marking every 2 m
Connector: To impulse generator IPG800 or IPG5000
Storage: On drum
Switch box: Switch between two vertical shot directions

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