CPT Sounding Tubes (36 mm)

This thread is called STANDARD, since it has been used by the CPT industry since the 1950-ies. Originally designed by Delft Geotechnics it has been adopted by all manufacturers of CPT equipment. Its advantage is that it is the world standard. It does not feature the advantages of its modern counterparts.

• Effective length: 1,000 mm
• Outer diameter: 36 mm
• Inner diameter: 16 mm
• Weight: 6.5 kg
• Required number of turns to lock / unlock: 7

By half of the 1990-ies CPT has become more-and-more a highly productive industry. Operators make up to 14 tests of 25 meter per 8-hour shift. Strain-injuries in wrists and elbows are becoming a real issue and the industry asks for a newly designed thread. This resulted in the Quick-Lock thread (also called Speed-Lock thread).

The main advantages are the number of turns required to lock / unlock (only 2.5 turns), the improved strength of the thread (over 40% stronger than the STANDARD thread) and the relative ease to clean it.

• Effective length: 1,000 mm
• Outer diameter: 36 mm
• Inner diameter: 16 mm
• Weight: 6.5 kg
• Required number of turns to lock / unlock: 2.5

Originally designed in the 1970-ies by A.P. van den Berg as a modern version of the standard tapered thread (see earlier). The mayor advantage was, that the relatively sharp thread was replaced by a much more easier to clean rope thread. The dimensions of the male and female thread are more in balance, making it somewhat stronger than the standard thread.

• Effective length: 1,000 mm
• Outer diameter: 36 mm
• Inner diameter: 16 mm
• Weight: 6.5 kg
• Required number of turns to lock / unlock: 6.5

Designed in the 1990-ies by A.P. van den Berg with the same design requirements as the earlier mentioned QLK double-entry rope thread. This thread was not designed from scratch, but based on the existing AR tapered rope thread.

The main improvement of the 2R thread over the AR thread is the number of turns required to lock / unlock (3.5 turns). It was not stronger than the AR thread and not as easy to clean as the QLK thread.

• Effective length: 1,000 mm
• Outer diameter: 36 mm
• Inner diameter: 16 mm
• Weight: 6.5 kg
• Required number of turns to lock / unlock: 3.5