Cracks, take the right measures
Choosing your gauge
How to choose your Saugnac gauge?
Below is a simplified guide to help you choose your gauge. We remain, of course, available to guide and advise you. What type of phenomenon do you wish to observe?2. A crack in a closed angle (90° angle)
5. An incline: for example, a wall that tips or tilts, a balcony that tips
6. Subsidence or deflection: for example, a beam that sags, a wall that “bellies out”
8. A complex movement along the 3 axes of space
9. None of the above: contact us to present your problem. We will certainly be able to offer you a solution.
| 1. A crack in a vertical surface (wall, external wall, bridge abutment, tower, etc.) or in a horizontal surface (floor, ceiling, arch, etc.) |
What does the crack look like?
1.1 The crack width is relatively constant along its length (crack with parallel lips) with no visible misalignment of one crack lip relative to the other 1.1 (when passing your hand over the crack, there is no noticeable “step” between the two lips)
1.2 The crack’s width is irregular along its length. This is the typical case of vertical cracks that are very often wider towards the top than at the bottom (e.g. pool cue crack). There is no misalignment of one crack lip relative to the other (no level difference between the two lips)
1.3 The crack’s width is irregular along its length and the lips are misaligned. (When you pass your hand over the crack, a difference in the level of the crack’s two lips can be felt). This reflects probable movement in all 3 dimensions.
| 1.1. The crack width is relatively constant along its length (crack with parallel lips). |
1.1.1. The crack is outdoors or in a wet room:
G1+ gauge: this is the most economical gauge and the easiest to read thanks to its unprecedented and patented direct decimal readout system (“digital” reading). This gauge has a precision of 1/20 mm: the G1+ can detect a movement of 0.05 mm
G1 gauge: this is the standard gauge used to simply measure changes along a single axis within a single plane, to within 1/10th of a mm
G1.2 gauge: same technical characteristics as the G1 gauge, but transparent for greater discretion.
If you want to save observation time with a more precise gauge
G1.5 gauge: this gauge is used to rapidly detect single axis crack movements with 1/50th precision, i.e. 0.02 mm. With the notable exception of problems related to soil movements (which generally require observation over a period of at least one year), this increased precision frequently allows the observation time to be reduced
If the gauge is to be read remotely (gauge difficult to reach on a bridge, tower, silo, etc.)
G4 gauge: this gauge allows you to measure single-axis and single-plane changes in cracks at distances of up to 50m, with a precision of 1/10th of a mm. Readings are made with binoculars.
1.1.2. The crack is located indoors, inside a dry room:
G1.1 gauge: same technical characteristics as the G1, but for indoor use only.
1.1.3. The crack is several centimetres wide, or requires anchor points relatively far apart
G1.3 gauge: this gauge is used to measure the movements of cracks up to 17 centimetres wide, with a precision of 1/10th of a mm
| 1.2. The crack’s width is irregular along its length. This is the typical case of vertical cracks that are very often wider towards the top than at the bottom (e.g. pool cue crack) |
This gauge has two verniers: a translation vernier to measure movement along the X axis and a rotation vernier to measure movement along the Y axis perpendicular to X (the readings from the 2 verniers can be entered into an Excel file by simple request. This file can then be used to accurately calculate the Y vertical movements according to the position of X)
| 1.3. The crack’s width is irregular along its length and the lips are misaligned |
Combining a G6 gauge and a G3 gauge will make it possible to track the movements of a crack on the X, Y (thanks to the G6 gauge) and Z (thanks to the G3 gauge) axes. These 2 gauges can be used both outdoors and indoors.
In the case of more complex movements, the 3 Dim Gauge with its 3 verniers (1 linear and 2 circular) can be used to observe any type of movement along the 3 axes of space.
| 2. A crack in a closed angle (90° angle) |
The crack in the angle has a relatively constant width (parallel lip crack)
2.1. The crack is outdoors or in a wet room :
G1+, G1 and G1.2 gauges, all supplied with folding strips, can easily be positioned in a 90° closed angle.
2.2. The crack is located indoors, inside a dry room:
G1.1 gauges supplied with folding strips can be very simply positioned in a closed angle at 90°
| 5. An incline: for example, a wall that tips or tilts, a balcony that tips |
G5 gauge: this gauge is used to measure changes in an incline or a deformation
This pendulum-based gauge is used to monitor the tilting of a building, wall or balcony with an accuracy of 0.02865°.
| 6. Subsidence or deflection: for example, a beam that sags, a wall that “bellies out” |
G130 gauge: this gauge is used to measure changes in deflection, tilting or point deformation
In some configurations (tipping retaining wall), it is sometimes possible to use the G130 gauge. We can determine the most appropriate solution with you.
This type of system requires a study adapted to your problem with a tailor-made solution proposal for each case.
| 7. A gap of 2 points several metres apart, including the off-load thrust of structures such as church walls. |
The G20 gauge can be used, for example, to check whether the distance between two parallel walls 10 m apart and measuring 20 m in height remains constant, with an accuracy of 1/10 mm. This is typically the case with the off-load thrust of church walls.