Temperature Sensor & Probe: Types, How It Works, & Applications

We all use temperature sensors in our daily lives, be it in the form of a thermometer, domestic water heater or refrigerator. Temperature sensors are a simple device that measures the degree of hotness or coolness and converts it into a readable unit. But, have you ever wondered how the temperature of the soil, boreholes, huge concrete dams or buildings is measured? Well, this also requires a few specialised temperature sensors.

Here we are going to tell you what is a temperature sensor, how does it work, where is it used, and what are its different types.

What Are Temperature Sensors?

Simply put, anything that measures hotness or coolness and gives the measurable output is known as a temperature sensor. For instance, a thermometer measures the degree of hotness with the help of the readable expansion or contraction in mercury.

And, a thermocouple converts the temperature into a voltage which is easily read by a Voltmeter. A thermostat, thermistor, and a thermocouple, all of these are temperature sensors.

The geotechnical field requires temperature sensors to measure the temperature change caused due to the seasonal variation or structural shift in large concrete constructions, deep boreholes, dams, soil, etc.

What Are The Different Temperature Sensors?

Model ETT-10V Vibrating Wire Temperature Sensor

The Encardio-rite model ETT-10V vibrating wire temperature meter is used for the measurement of internal temperature in concrete structures or water. It has a resolution of better than 0.1°C and works similar to that of Thermocouple Temperature Sensors

How Does Model ETT-10V Vibrating Wire Temperature Sensor Works?

The vibrating wire temperature meter is designed on the principle that dissimilar metals have a different linear coefficient of expansion with temperature variation. It basically consists of a magnetic, high tensile strength stretched wire, the two ends of which are fixed to any dissimilar metal in a manner that any change in temperature directly affects the tension in the wire and, thus, its natural frequency of vibration.

The dissimilar metal, in the case of the Encardio-rite temperature meter, is aluminium. As the temperature signal is converted into frequency, the same read-out unit as is used for other vibrating wire sensors can also be used for monitoring temperature also.

The change in temperature is sensed by the specially built Encardio-rite vibrating wire sensor and is converted to an electrical signal which is transmitted as a frequency to the read-out unit.

The frequency, which is proportional to the temperature and in turn to the tension ‘σ’ in the wire, can be determined as follows:

f = 1/2 [σg/ρ] / 2l Hz

Where:

σ = tension of the wire

g = acceleration due to gravity

ρ = density of the wire

l = length of wire

Model ETT-10TH Resistance Thermistor Probe

The Encardio-rite model ETT-10TH resistance temperature probe is a low mass waterproof temperature probe for measurement of temperature between –20 to 80°C. Due to its low thermal mass, it has a fast response time.

Model ETT-10TH resistance temperature probe is specially designed for the measurement of surface temperatures of steel & measurement of the surface temperature of concrete structures. ETT-10TH can be embedded in concrete for measurement of bulk temperature inside the concrete and can even work submerged underwater.

ETT-10TH resistance temperature probes are fully interchangeable. The temperature readings will not differ by more than 1°C over the specified working temperature range. This allows a single indicator to be used with any ETT-10TH probe without recalibration.

Encardio-rite’s model EDI-51V vibrating wire indicator when used with ETT-10TH directly shows the probe temperature in degree Celsius.

How Does Model ETT-10TH Resistance Thermistor Probe Works?

ETT-10TH temperature probe consists of a resistance-temperature curve matched thermistor epoxy encapsulated in copper tubing for faster thermal response and environmental protection. The tube is flattened at the tip so that it can be fixed to any reasonably flat metal or concrete surface for measurement of surface temperature.

The flat tip of the probe can be fixed to most surfaces with the help of easily available two-part epoxy adhesives. If desired, the probe can also be bolted down to the surface of the structure.

The temperature probe is provided with a four-core cable used as a standard in all Encardio-rite vibrating wire strain gauges. The pair of white and green coloured wires are used for the thermistor which is the same as for other Encardio-rite vibrating wire sensors with an integral thermistor temperature sensor.

The pair of red and black wires are left unused. The use of a uniform colour scheme across different sensors makes it easier to make error-free connections to a junction box or data logger terminal panels.

Model ETT-10PT RTD Temperature Probe

The ETT-10PT RTD (Resistance Temperature Detector) temperature probe consists…[Continue Reading]