Strain Gauges & Thermometers

ARC WELDABLE AND EMBEDMENT STRAIN GAUGES

Geozone Geoservices_Geotechnical instrumentation_Arc weldable & embedment strain gaugesVibrating wire strain gauges are used to monitor strain in steel or in reinforced concrete and mass concrete structures. Arc-weldable vibrating wire strain-gauges are designed for arc welding to steel structures such as tunnel linings, piles and bridges. The gauge is supplied with end mounting blocks. Embedment vibrating wire strain-gauges are directly embedded in concrete for strain measurements of piles, foundations, dams, tunnels linings, etc. Vibrating wire strain-gauges are particularly durable and thermally-aged to minimize long-term drift and changes in calibration. Thermistor is incorporated in the coil housing. The standard gauge length is 150mm with a nominal range of 3000 µε.

Technical Specifications

0VK4000VS00 ARC-WELDABLE GAUGE
0VK4200VC00 EMBEDMENT GAUGE
0VK4200VN00 NO-STRESS EMBEDMENT GAUGE
Active gauge length 150mm
Measuring range 3000 µε (nominal)
Sensitivity 1 µε
Total accuracy < 2% FS
Stability 0.1% FS/ year
Frequency datum 800 Hz typical
Coil resistance 150 Ω
Temp. operating range -20°C +60°C
Accessories
0VK42VC3D00 Mounting block for rosette 3-D assembling (X-Y-Z directions)
0VK400JIG00 Mounting jig for weldable strain-gauges
0VK400MB200 Pair of arc-weldable surface mounting blocks

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SPOT WELDABLE STRAIN GAUGES

Geozone Geoservices_Geotechnical instrumentation_Spot weldable strain gaugesSpot weldable strain gauges are designed to measure strains in steel structures. They can be installed quickly and easily in the field using the portable spot welder only. Installation can be also made by epoxy bonding the gauge onto the structure. The spot weldable strain gauge has a removable coil unit, which also incorporates the built-in thermistor for temperature measures. If the gauge location is not accessible the coil unit is attached permanently on the gauge. The spot weldable strain gauge is a small size gauge with 50.4mm active gauge length. The wire tension can be set to place the range mostly in compression or mostly in tension by means of leaf springs.

Technical Specifications
VW SPOT WELDABLE STRAIN GAUGE
(Product code 0VK4100VS00)

Range 3000 µε (nominal)
Sensitivity 1.0 µε
Resolution 40 µε
Thermal coeff. of expansion 11.3×10-6/°C
Temperature range -20°C +80°C
Active gauge length 50.4 mm
Overall length 63.5 mm nominal
Accessories
0VK410PSW00 Portable spot welder
0VK410KIT00 Leaf spring installation kit

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VIBRATING WIRE REBAR AND SHOTCRETE STRAIN GAUGES

Geozone Geoservices_Geotechnical instrumentation_Vibrating Wire Rebar & shotcrete strain gaugesRebar strain-meters are designed for direct embedment in concrete. They are used for measuring strain in foundations, concrete walls, piles and bridge abutments. Rebar incorporates the vibrating wire strain gauge element with plucking coil. A thermistor is included in each strain meter as a standard feature and permits measurement of temperature at the rebar strain meter location. Vibrating wire rebar strain meters are available in different units in order to match the sizes of the concrete reinforcing bars. They are intended to be welded at their ends into the rebar system and so the rebar size is chosen to match the existing reinforcing bar.

Technical Specifications

0VKBAR01800 VW REBAR 18 MM NOMINAL OD
0VKBAR02200 VW REBAR 22 MM NOMINAL OD
0VKBAR02600 VW REBAR 26 MM NOMINAL OD
0VKBAR03000 VW REBAR 30 MM NOMINAL O
Range 2500 µε (nominal)
Sensitivity 1.0 µε
Accuracy < 2% FS
Stability 0.1% FS/yr
Nominal gauge factor 3.38 x 10-4 µε /f2
Typical electric output 1900 ± 200 Hz
Coil Resistance 152 to 158 Ω
Temperature range -20°C +70°C
Bar length 400 mm

SHOTCRETE STRAIN GAUGES
(Product code 0VK4000SM00)
Shotcrete vibrating wire strain gauges are designed for tunnel monitoring where shotcrete is used for concrete lining; in fact this method requires a higher working range than common vibrating wire strain gauges.

Range 10000 µε (nominal)
Sensitivity 1.0 µε
Resolution 40 µε
Thermal coeff. of expansion 11.3×10-6/°C
Temperature range -20°C +80°C
Gauge length 200 mm

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RESISTIVE STRAIN GAUGES

Geozone Geoservices_Geotechnical instrumentation_Resistive strain gaugesThe resistive strain gauge incorporates four high output electrical strain gauges in full bridge configuration bonded to a steel bar. This arrangement allows compensation for both temperature and bending effects. Resistive strain gauges offer a valid alternative to the vibrating wire type when continuous measurements are required. They have a standard length of 400 mm and are available in two models: for embedment in concrete or welded onto steel surfaces. Measurements are carried out by Torricelli readout or Leonardo portable datalogger. Automatic monitoring can be obtained by ADK-100 data acquisition system.

Technical Specifications

0L3400VS000 STRAIN-GAUGE BAR, mV/V O/P
0L3400VSC00 STRAIN-GAUGE BAR, V O/P
0L3400AS000 STRAIN-GAUGE BAR, 4-20 mA O/P
Nominal load 1000 Kg
Bar section 8×8 mm
Bar length 400 mm
Measuring range ±1500 µε (nominal)
Sensitivity 0.0015 mV/ µε
Total accuracy < 1% FS
Zero temp. drift <0.05% FS
Signal output 2 mV/ at FS
4-20 mA (current loop)
Temp. operating range -20°C +70°C
CABLES AND ACCESSORIES
0WE10600000 Electric cable 6 wires (24 AWG) for strain gauges mV/V or V output
0WE102KEO00 Electric cable 2 wires (20 AWG) for strain gauges 4-20mA output
0L3400MB200 Pair of welding blocks for resistance strain gauges

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EMBEDMENT THERMOMETERS

Geozone Geoservices_Geotechnical instrumentation_Embedment thermometersTemperature is a very important parameter in order to evaluate the influence of thermal effects on the measurements and the structure which is being monitored. Sisgeo uses two types of practical devices to monitor temperature: thermistors and RTDs (Resistance Thermal Detectors). RTDs provide highest accuracy in comparison with thermistors and thermocouples. The RTD is precision trimmed in manufacture using a platinum device of 100 ohms at 0°C which guarantees long-term stability. Both RTDs and thermistors are housed in a shock resistant stainless steel body for application in air, water and for direct embedment in concrete.

Technical Specifications
RTD THERMOMETER
(Product code 0T111PT1000)

Type of sensor PT100
platinum resistance 100 Ω at 0°C
Measuring range -50°C +150°C
Resolution 0.1°C
Accuracy 0.2°C
Diameter 22 mm
Length 100mm
Material stainless steel
THERMISTOR
(Product code 0T3800GKA00)
Type of sensor NTC thermistor (YSI 44005)
Measuring range -50°C +150°C
Resolution 0.1°C
Accuracy 0.5°C
Diameter 12 mm
Length 55 mm
Material stainless steel

C6003 RTD INDICATOR
(Product code 0C600300000)

Temperature readings on 0T111PT1000 thermometers can be taken using a small digital multimeter to measure the resistance of the thermoresistance and then convert it to temperature via a conversion chart which shows the relationship between temperature (C°) and resistance (K Ω).

Type of measure RTD
Display 3.5 large size LCD
Accuracy ±digit
Internal battery rechargeable 5×1.2 V–1Ah Ni-Cd
Enviromental -5°C + 50°C dustproof case

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PORTABLE THERMAL PROBES

Geozone Geoservices_Geotechnical instrumentation_Portable thermal probesThe portable thermal probes are designed for both water temperature and water level measurements in wells, boreholes and standpipe piezometers. It consists of a dipping probe mounted on a millimetre tape. Tape is wrapped on a rugged portable reel, which contains electronic and battery pack. The dipping probe mounts a microchip-based integrated circuit (IC) for temperature measures that produces an output proportional to absolute temperature. Temperature values are directly displayed in °C on a 3.5 LCD mounted on the face-plate of the reel where are also located the front panel controls.

Technical Specifications

Temperature transducer IC 590
Cable lengths 30, 50, 100, 150m
Temperature range -50°C +150°C
Resolution 0.1°C
Accuracy ± 0.5°C
Probe diameter 10 mm
Digital display 3.5 LCD
Batteries (2) 9V DC disposal
Operating time about 20 hours

SPARE SET FOR C112T
(Product code 0C112TKITR0)
Spare set for portable water-thermal probe includes probe, weights, epoxy resin and consumable.

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IC 590