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.
Operation
The VW temperature sensor consists of a stainless steel body, a wire held in tension within the body, an electromagnetic coil, and 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 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 temperaure sensor 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 properly 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 Sensor | 52631510 |
| Sensor Type | Pluck 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 |
| Resolution | 0.025% FS |
| Calibration Accuracy | ±0.5% FS |
| Response Time | 2.5 minutes for 60% of full thermal equilibrium |
| Full Thermal Equilibrium | 15 minutes |
| Dimensions | 19 x 115 mm (0.75 x 4.5") |
| Materials | Brass body |
| Weight | 145 g (0.32 lb.) |
| SIGNAL CABLE FOR VW SENSOR | ||
|---|---|---|
| Signal Cable | 50613524 | Shielded 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 Sensor | 92600056 | |
| Thermistor Temperature Sensor | 92600057 | These 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 Type | RTD (2 k ohm) or Thermistor (3 k ohm) | |
| Range | -20 to 80°C. Other ranges available | |
| Resolution | 0.2°C with VW Data Recorder | |
| Accuracy | ±0.5°C FS | |
| Dimensions | 9.5 x 101 mm (0.375 x 4") | |
| Materials | Brass body | |
| Weight | 50g (0.11 lb.) | |
| Signal Cable | Same as VW temperature sensor | |
| Readout and Data Loggers | VW Data Recorder and most types of data loggers | |
| SIGNAL CABLE | ||
|---|---|---|
| Signal Cable | 50613524 | Shielded cable with four copper conductors and cable jacket rated to 80°C. Specify cable length required for each sensor. Can be used with VW, RTD, or Thermistors |
| High-Temperature Signal Cable | 52602320 | For use only with RTDs or thermistors. Shielded cable with two copper conductors and thermal rubber jacket rated to 115°C |
| READOUTS | ||
|---|---|---|
| VW Data Recorder | 52613500 | VW 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 Box | 52613557 | |
| TERMINAL BOXES | ||
|---|---|---|
| Terminal Box for 6 sensors | 57711606 | Provides 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 Sensors | 57711600 | |
| Terminal Box for 24 Sensors | 97711624 | |
