Temperature Sensors

Applications

Temperature sensors are used to monitor the heat of hydration in mass concrete structures. They can also be used to monitor migration of ground water or seepage.

Sensor Type

  • Vibrating wire temperature sensors offer high accuracy and are convenient when other types of VW sensors are used.
  • Resistance temperature sensors (RTDs or Thermistors) are a less precise, but economical alternative to the vibrating wire sensor.
Temperature Sensors

Operation

The VW temperature sensor consists of a stainless steel body, a wire held in tension within the body, an electromagnetic coil, and a signal cable. The body of the sensor expands and contracts with changes in temperature, increasing or decreasing the tension of the wire inside the body. When a readout is connected to the sensor, it sends an electric pulse to the coil, which plucks the wire and causes it to vibrate at its natural frequency. A second coil picks up the vibration and returns a frequency to the readout. The frequency reading is converted to units of temperature by applying calibration factors.

The resistance temperature sensor consists of a stainless steel body, an RTD or thermistor inside the body, and a signal cable. The resistance of the RTD or thermistor varies with temperature. Resistance temperature sensors can be read with standard VW readouts, which have built-in conversion factors to convert the resistance reading to units of temperature.

Advantages

  • High Accuracy: The VW temperature sensor has an accuracy better than ± 0.3°C. Resistance temperature sensors offer an accuracy of ± 0.5°C.
  • VW Compatible: The VW temperature sensor is especially convenient when there are other VW sensors at the site.
  • Manual or Automatic Readings: Both types of temperature sensors can be read manually using the VW Data Recorder or automatically using a data logger. Data logger connections for resistance sensors are different from those for VW sensors.
  • Reliable Signal Transmission: The strong VW signal can be transmitted reliably over long distances with a proper shield cable.

For more information

Please download PDF datasheets and manuals. They can be viewed and printed with Adobe Reader.

Datasheet for both VW and Resistance Temperature Sensors

Manual for the VW Temperature Sensor

Manual for the Resistance Temperature Sensor

Temperature Sensors Specifications

VW TEMPERATURE SENSOR
VW Temperature Sensor52631510
Sensor TypePluck type vibrating wire sensor with built-in thermistor or RTD and transient protection device
Range-20 to 80°C (100° Span). Other ranges available on special order
Resolution0.025% FS
Calibration Accuracy±0.5% FS
Response Time2.5 minutes for 60% of full thermal equilibrium
Full Thermal Equilibrium15 minutes
Dimensions19 x 115 mm (0.75 x 4.5")
MaterialsBrass body
Weight145 g (0.32 lb.)
SIGNAL CABLE FOR VW SENSOR
Signal Cable50613524Shielded cable with four copper conductors and cable jacket rated to 80°C. Specify cable length required for each sensor
RTD AND THERMISTOR SENSORS
RTD Temperature Sensor92600056
Thermistor Temperature Sensor92600057These economical temperature sensors employ resistance temperature devices rather than vibrating wire transducers. When read by standard VW readouts, they return a reading in degrees C. Otherwise, they return a voltage reading that can be converted to units of temperature by applying calibration factors.
Sensor TypeRTD (2 k ohm) or Thermistor (3 k ohm)
Range-20 to 80°C. Other ranges available
Resolution0.2°C with VW Data Recorder
Accuracy±0.5°C FS
Dimensions9.5 x 101 mm (0.375 x 4")
MaterialsBrass body
Weight50g (0.11 lb.)
Signal CableSame as VW temperature sensor
Readout and Data LoggersVW Data Recorder and most types of data loggers
SIGNAL CABLE
Signal Cable50613524Shielded cable with four copper conductors and cable jacket rated to 80°C. Specify the cable length required for each sensor. Can be used with VW, RTD, or Thermistors
High-Temperature Signal Cable52602320For use only with RTDs or thermistors. Shielded cable with two copper conductors and thermal rubber jacket rated to 115°C
READOUTS
VW Data Recorder52613500VW Data Recorder reads VW sensors and returns a reading in volts. It also reads RTDs and Thermistors and returns a reading in degrees C
Jumper to Terminal Box52613557
TERMINAL BOXES
Terminal Box for 6 sensors57711606Provides terminals for signal cable from 6, 12, or 24 sensors. Sensors are selected by rotary switch. Small 6-sensor box is 240 x 190 x 120 mm (9.5 x 7.5 x 4.75"). Larger 12 and 24-sensor box measures 290 x 345 x 135 mm (11.5 x 13.5 x 5.25")
Terminal Box for 12 Sensors57711600
Terminal Box for 24 Sensors97711624