Photo of Model 3900.

Embedment Strain Gages

Model 3900

The Model 3900 Embedment Strain Gage is designed for the measurement of dynamic strains in concrete structures, earth fills and soils. Special high-temperature versions are also available for use in asphalt. It comprises a full bridge strain gaged proving ring coupled, between two flanges, with a spring and shaft. When the flanges move relative to one another, the tension in the spring changes and hence the strain in the proving ring. A PVC tube serves as a protective housing and holds the gage at the desired initial tension.

Specifications
Standard Range 5000 µε
Resolution 0.125 mV/V nominal
Accuracy ±0.25% F.S.
Nonlinearity <0.5% F.S.
Temperature Range −20°C to +80°C
Active Gage Length¹ 203 mm

¹Other lengths available on request.

Photo of Model 4000.

Arc Weldable Strain Gages

Model 4000

The Model 4000 Strain Gage is designed primarily for arc welding to steel structures such as tunnel linings, excavation bracing, piles and bridges. The gage has a 150 mm gage length (longer or shorter versions are also available) a 3000 µε range and a 1 µε sensitivity. The gage can be adapted for bonding to concrete or for bolting to steel surfaces by modification of the end blocks.

Specifications
Standard Range 3000 µε
Resolution 1.0 µε
Accuracy¹ ±0.5% F.S.
Nonlinearity <0.5% F.S.
Temperature Range −20°C to +80°C
Active Gage Length² 150 mm

¹Accuracy of ±0.1% F.S. available with optional, individual calibration.

²Other lengths available on request.

Photo of Model FP4000.

Fiber Optic Strain Gages

Model FP4000

The Model FP4000 Fiber Optic Strain Gages are designed for use in environments where it may be difficult to use conventional types of strain gages because of space considerations, high levels of electrical interference or where intrinsic safety is an issue. Measurements of dynamic events are also possible with these gages and the requisite dataloggers. The strain gages have a very low coefficient of thermal expansion and can be used to measure both mechanical and thermo-mechanical strains in a variety of different materials.

Specifications FP4000-1.0 FP4000-2.5 FP4000-5.0

Standard Ranges

−1000

to +1000 µε

−2500

to +2500 µε

−5000

to +5000 µε
Resolution 0.15 µε 0.30 µε 0.50 µε
Gage Factor Accuracy¹ ±3% F.S. ±3% F.S. ±10% F.S.

Temperature Sensitivity

0.85 to

1.22 µε/°C

0.85 to

1.22 µε/°C

0.85 to

1.22 µε/°C

Transverse

Strain Sensitivity

transverse

strain insensitive

transverse

strain insensitive

transverse

strain insensitive

Temperature

Operating Range²

−40°C

to +250°C

−40°C

to +250°C

−40°C

to +250°C
L × W × H

100×25×1 mm

100×25×1 mm

100×25×1 mm

¹The accuracy of the OSP sensors is determined by sample testing of controlled batches at the factory. The manufacturing technique results in the spans shown above and is confirmed by actual strain tests performed on samples from batch lots.

²Other ranges available on request.

Photo of Model 4100 and 4150.

Spot Weldable Strain Gages

Model 4100, 4150

The Model 4100/4150 Strain Gage has a 51 mm gage length (3000 µε range, 1 µε sensitivity) and is designed to measure strains in steel structures (4100) and on reinforcement bars (4150) where space may be limited. The gage is installed quickly and easily by means of a capacitive discharge spot welder or, for short-term use, with special epoxy adhesives; the latter method of attachment permits the use of this gage on concrete.

Specifications 4100 4150
Standard Range 3000 µε 3000 µε
Resolution 0.4 µε 0.4 µε
Accuracy¹ ±0.5% F.S. ±0.5% F.S.
Nonlinearity <0.5% F.S. <0.5% F.S.
Temperature Range −20°C to +80°C −20°C to +80°C
Active Gage Length 51 mm 51 mm

¹Accuracy of ±0.1% F.S. available with optional, individual calibration.

Photo of Model 4151.

Miniature (Surface Mount) and Extended Range Strain Gages

Model 4151

The Model 4151 is a modification of the 4150 strain gage in which the spot-weldable tabs have been replaced by pins welded to the end blocks and designed to be grouted into two short holes drilled into the material under test. Special versions of the Model 4151 are available with extended ranges. These gages are particularly useful for measurements in high strain regimes such as on plastic pipes or piles and on fiberglass structural members and rebars. A unique design allows these gages to be manufactured without increasing their overall length, making them particularly suitable where space and or access is limited.

Specifications 4151 4151-1 4151-2
Range (Nominal) 3000 µε 5,000 µε¹ 10,000 µε¹
Resolution 0.4 µε 1.0 µε 2.0 µε
Accuracy² ±0.5% F.S. ±0.5% F.S. ±0.5% F.S.
Linearity <0.5% F.S. <0.5% F.S. <0.5% F.S.
Temperature Range −20°C to +80°C −20°C to +80°C −20°C to +80°C
Active Gage Length 51 mm 51 mm 51 mm

¹Depends on the readout; figures above pertain to the GK-401 Readout.

²Accuracy of ±0.1% F.S. available with optional, individual calibration.

Photo of Model 4200, 4210 and 4202.

Concrete Embedment Strain Gages

Model 4200, 4202, 4210

These Strain Gages are designed for direct embedment in concrete. The 4200 (standard model) has a 153 mm gage length and 1 με sensitivity and is commonly used for strain measurements in foundations, piles, bridges, dams, tunnel linings, etc. The 4210 has a 250 mm gage length making it particularly suitable for use in large aggregate concrete. The 4202 is designed for laboratory use and/or where there are space limitations. Low modulus versions, for measuring concrete curing strains, are also available (please contact Geokon, Inc. for details).

Specifications 4200 4202 4210
Standard Range 3000 µε 3000 µε 3000 µε
Resolution 1.0 µε 0.4 µε 0.4 µε
Accuracy¹ ±0.5% F.S. ±0.5% F.S. ±0.5% F.S.
Nonlinearity <0.5% F.S. <0.5% F.S. <0.5% F.S.
Temperature Range −20°C to +80°C −20°C to +80°C −20°C to +80°C
Active Gage Length 153 mm 51 mm 250 mm²

¹Accuracy of ±0.1% F.S. available with optional, individual calibration.

²Other lengths available on request.

Photo of Model 4200HT.

High Temperature Embedment Strain Gages

Model 4200HT

The Model 4200HT High Temperature Embedment Strain Gage is similar to the standard Model 4200 but is constructed using components that can be used at temperatures up to 200°C. It is particularly useful for measurements in autoclaved spun concrete piles.

Specifications
Standard Range 3000 µε
Resolution 1.0 µε
Accuracy¹ ±0.5% F.S.
Nonlinearity <0.5% F.S.
Temperature Range −20°C to +200°C
Active Gage Length 144 mm

¹Accuracy of ±0.1% F.S. available with optional, individual calibration.

Photo of Model 4911 and 4911A.

Rebar Strainmeters

Model 4911, 4911A

The Model 4911 Rebar Strainmeter is designed for measuring strains in foundations, slurry walls, precast piles, caissons, bridge abutments, tunnel liners, etc. The standard Model 4911 (#4 rebar), known as the “Sister Bar”, is installed alongside structural rebar. Larger models (4911A) are available for welding directly into structural rebar. Where short-term dynamic measurements are to be made, bonded resistance (Model 3911/3911A) strain gages can be substituted, or added.

Specifications 4911 4911A
Standard Range 2500 µε 2500 µε
Resolution 0.4 µε 0.4 µε
Accuracy ±0.25% F.S. ±0.25% F.S.
Nonlinearity <0.5% F.S. <0.5% F.S.
Temperature Range −20°C to +80°C −20°C to +80°C
Rebar Sizes 4 (Sister Bar) 6, 7, 8, 9, 10, 11, 12
Active Gage Length 1384 mm 1105 mm

Photo of Model FP4911.

Fiber Optic Rebar Strainmeters

Model FP4911

The Model FP4911 Fiber Optic Rebar Strainmeter is designed for measuring strains in foundations, slurry walls, precast piles, caissons, bridge abutments, tunnel liners, etc. The standard Model FP4911 (#4 rebar), known as the “Sister Bar,” is installed alongside structural rebar. The Fibre Optic element employed in this sensor makes it particularly suitable where dynamic measurements are to be made and/or on projects where other fiber optic sensors are deployed.

Specifications
Standard Range −1000 to +1000 µε
Resolution 0.15 µε
Accuracy ±0.25% F.S.
Nonlinearity <0.5% F.S.
Temperature Sensitivity 0.85 to 1.22 µε/°C
Temp. Operating Range¹ −40°C to +250°C
Rebar Size 4 (Sister Bar)
Active Gage Length 1384 mm

¹Other ranges available on request.

Products

Please Note: Geokon maintains an ongoing policy of design review and reserves the right to amend products and specifications without notice.