3 Arm Caliper


The QL40-CAL sub records a single continuous borehole diameter log by means of three mechanically coupled arms in contact with the borehole wall. The 3 arm caliper measurement is a useful first log to determine the borehole condition before running other probes.

The QL40-CAL sub can be combined with other logging tools of the QL (Quick Link) product line or can be operated as a standalone tool. It is compatible with Matrix and Scout logger acquisition systems.

The QL40 CAL is supplied with two sets of arms. The standard arms are suitable for a borehole diameter ranging from 57 mm to 406 mm. The extension arms are suitable for borehole diameters up to 736mm. The caliper arms can be unscrewed from their short pivot arms and may be replaced with ones of different length. The hardened arm wear tips can be unscrewed and are easily replaced.

Temperature – Pressure

0-70°C (32-158°F)
200 bar (2900 psi)

Diameter – Length

40 mm (1.6”) – 1.87 m (73”)


8.7 kg


Calibrated measurement of borehole diameter in inches, centimeters or millimeters

Easy exchangeable short and long caliper arms and wear tips


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

If you have a question OR REQUIRE A QUOTE, CONTACT us and one of our professional team members will assist you