Photo of Model 4800.

Earth Pressure Cells

Model 4800

The Model 4800 Earth Pressure Cells are designed to measure total pressure in earth fills and embankments. All cells consist of two circular stainless steel plates welded together around their periphery and spaced apart by a narrow cavity filled with de-aired oil. Changing earth pressure squeezes the two plates together causing a corresponding increase of fluid pressure inside the cell. The vibrating wire pressure transducer converts this pressure into an electrical signal which is transmitted as a frequency via cable to the readout location.*

Specifications
Standard Ranges 70, 170, 350, 700 kPa; 1, 2, 3, 5, 7.5, 20 MPa
Over Range 150% F.S. (maximum)
Resolution 0.025% F.S.
Accuracy¹ ±0.1% F.S.
Temperature Range −20°C to +80°C
Height × Diameter² 6 × 230 mm

¹Calibrated accuracy of the pressure sensor.

²Other sizes available on request.

Photo of Model 4810.

“Fat Back” Pressure Cells

Model 4810

The Model 4810 “Fat Back” Pressure Cell is intended to measure contact earth pressures on the surface of concrete or steel structures. The cell has an extra thick backplate to minimize any point loading effects. ‘Ears’ on the cell assist in holding the cell to concrete forms or to retaining walls during installation.*

Specifications
Standard Ranges¹ 350, 700 kPa; 1, 2, 3, 5 MPa
Over Range 150% F.S. (maximum)
Resolution 0.025% F.S.
Accuracy² ±0.1% F.S.
Temperature Range −20°C to +80°C
Height × Diameter¹ 12 × 230 mm

¹Other ranges and sizes available on request.

²Calibrated accuracy of the pressure sensor.

Photo of Model 4820.

Photo of Model 4820 Jackout Pressure Cell Hydraulic Jack Assembly.

Jackout Pressure Cells

Model 4820

The Model 4820 Jackout Pressure Cells are used to measure earth pressures on slurry walls. They are designed to fit inside a plate which is pressed against the side of a slurry wall excavation using a hydraulic jack arrangement. This method of installation ensures that the jack out cell is located with its sensitive face in contact with the adjacent soil. (Photo at left shows the Jackout Pressure Cell separately, as removed from the assembly. Photo at lower left shows Jackout Pressure Cell Hydraulic Jack Assembly (with VW Piezometer installed).*

Specifications
Standard Ranges 350, 700 kPa; 1, 2, 3, 5 MPa
Over Range 150% F.S. (maximum)
Resolution 0.025% F.S.
Accuracy ±0.1% F.S.
Temperature Range −20°C to +80°C
Height × Diameter¹ 12 × 150 mm

¹Other sizes available on request.

Photo of Model 4830.

Push-In Pressure Cells

Model 4830

The Model 4830 Push-In Pressure Cell is designed to be pushed in place for the measurement of total pressures in soils and earth fills. Where effective stress is required, the cell is fitted with an integral piezometer. A thread is provided on the end of the cell to allow for installation using lengths of pipe or drill rods.*

Specifications
Standard Ranges 70, 170, 350, 700 kPa; 1, 2, 3, 5 MPa
Over Range 150% F.S. (maximum)
Resolution 0.025% F.S.
Accuracy ±0.1% F.S.
Temperature Range −20°C to +80°C
Length × Diameter¹ 600 × 50 mm

¹Other sizes available on request.

Photo of Model 4850.

Concrete Stress Cells (NATM Style)

Model 4850

The Model 4850 NATM Style Concrete Stress Cells are designed for the measurement of tangential (4850-1) and radial (4850-2) stresses in shotcrete tunnel linings. The cells consist of two rectangular steel plates welded together around the periphery with a de-aired fluid occupying the space between the plates. A short tube connects the cell to a vibrating wire pressure transducer. For environmental protection, no mercury is used in these cells. A prestressing tube is provided for expanding the cell after the concrete has cured. Cells of this type are also used for measurements of stress in mass concrete.

Specifications 4850-1 4850-2
Standard Ranges¹ 7.5, 20, 35 MPa 2, 3, 5 MPa
Over Range 150% F.S. 150% F.S.
Resolution 0.025% F.S. 0.025% F.S.
Accuracy ±0.1% F.S. ±0.1% F.S.
Temperature Range −20°C to +80°C −20°C to +80°C
L × W × H² 200 × 100 × 6 mm 250 × 150 × 6 mm

¹Other pressure ranges available on request.

²Other sizes available on request.

Photo of Model 4900.

Load Cells

Model 4900

The Model 4900 Vibrating Wire Load Cell consists of a cylinder of high-strength, heat treated steel with 3, 4 or 6 vibrating wire strain gages located around the circumference of the cell. Loads applied to the cell are measured by the vibrating wire strain gages. The effects of uneven and eccentric loading are minimized by averaging the output of all 3, 4 or 6 individual readings.

Specifications
Rated Capacities¹ 1 to 10,000 KN
Over Range 150% F.S.
Approximate Resolution 0.025% F.S.
Accuracy ±0.25% F.S. to ±0.5% F.S.
Temperature Range −20°C to +80°C
Internal Diameters¹ solid, 25, 50, 75, 100, 125, 150, 200, 250 mm

¹Other capacities and diameters available on request. Calibrations that exceed Geokon’s NIST traceable capacity of approximately 4500 kN are subcontracted to an accredited testing laboratory.

Photo of Model 3000.

Load Cells

Model 3000

The Model 3000 Load Cell is made from an annulus of high-strength steel or aluminum on which several electrical resistance strain gages are located. The load cell is designed primarily for use on tiebacks and rockbolts although they may be used during pile load tests and for monitoring loads in crosslot struts and tunnel supports, etc. In most cases, the load cells are used in conjunction with a hydraulic jack and bearing plates.

Specifications
Rated Capacities¹ 100, 150, 200, 300, 500, 600, 1000, 1500, 2000 kips
Over Range 200% F.S. for aluminum; 300% - 400% for steel
Linearity 0.5% F.S.
Accuracy 0.5% F.S.; 0.1% with polynomial expression
Input Resistance 350 or 700 ohms
Temperature Range −20°C to +80°C
Internal Diameters¹ solid, 25, 50, 75, 100, 125, 150, 200, 250 mm

¹Other capacities and diameters available on request. Calibrations that exceed Geokon’s NIST traceable capacity of approximately 4500 kN are subcontracted to an accredited testing laboratory.

Photo of Model 4910.

Instrumented Rockbolts

Model 4910

The Model 4910 Instrumented Rockbolt comprises a vibrating wire strain gage located inside a short length of standard threaded rockbolt or rebar. This short length is then connected via a coupling to a longer length of the same bolt material. The instrumented rockbolt is installed in the same manner as conventional rockbolts , making sure that the strain gage remains located within the loaded part of the rockbolt.

Specifications
Standard Range

2500 µε, equivalent to around 27,215 kg in a

25 mm Ø bolt
Resolution 0.5 µε, equivalent to around 5 kg in a 25 mm Ø bolt
Accuracy ±0.25% F.S.
Linearity ±0.5% F.S.
Output 1400-3000 Hz
Temperature Range −20 to +80°C
Bolt Sizes 25 mm, #8 rebar, and larger
Length 300 mm (standard)

Photo of Model 4915.

Tension Load Cells

Model 4915

The Model 4915 Load Cell consists of a vibrating wire transducer, housed inside a thick-walled stainless steel cylinder, designed to provide a highly stable and sensitive means of monitoring tensile loads in in-line weighing systems, such as weighing type rain gages, process weighing systems and batching plants.

Specifications
Rated Capacity¹ 15 kg
Over Range 150% F.S.
Resolution 0.025% F.S.
Accuracy ±0.1% F.S.
Temperature Range −20°C to +80°C
Length × Diameter 94 × 19 mm (transducer)

¹Other capacities available on request.

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