Temperature sensors are used to evaluate the amount of heat or the coldness. The coldness or the heat energy that is generated by any system or the object. It shows the difference in the heat or the cold levels if there is any change in the temperature. The output is produced in analog or digital output. Different types of sensors are available with different features. Basically there are two different physical types of temperature sensors.
Contact Temperature Sensor Types
This type of sensor should be contacted physically with the object which should be sensed. The changes in the temperature will be shown in the monitor. It is widely used to find liquids, solids and gases.
Non-contact Temperature Sensor Types
This temperature sensor use radiation and convection to find the changes in the temperature. It is used to find the gases and the liquids that emit energy that is radiant. The radiant energy is detected when it is transmitted in infra-red radiation.
The contact and non-contact temperature sensors are classified as:
• Electro mechanical
This is a electro mechanical type temperature sensor which is a contact type. It contains nickel, aluminum and copper. These metals form a bi-metallic strip through bonding. The bimetallic strip is also used as mechanical or electrical switch. It is widely used in the furnace and the boilers and in radiators of vehicle to find the heat levels.
The Bi-metallic Thermostat
In this thermostat two different metals are fixed against each other back to back. If it is cold, then current will pass as the contacts of the metals are closed whereas if it is hot then one of metal of the tow metals will raise more and the bimetallic strip that is bonded will bend upwards to prevent the current flowing in.
Thermostat temperature sensor
In regard with the bimetallic strips, there are two different but main types and it is differentiated depended on the movement as per the changes in the temperature. The ON/OFF type is otherwise called as snap-action types which produces instant ON or OFF action as per the temperature point. The action will be produced on the electrical contacts. The creep action type of thermostats is also called as slower types. The position of the strip is changed gradually according to the changes in the temperature.
The snap action or ON/OFF type thermostats are mostly used in homes to control the temperature points of irons, ovens, immersion hot water tanks, iron and also in domestic heating system.
The creeper type thermostats are usually bimetallic spiral or coil which will unwind as per the temperature changes. This type of thermostat is quite extra sensitive to the changes in temperature. The snap action and creeper type of thermostat are cheaper comparatively.
This is one of the temperature sensor which consists of special type of resistor. When there is change in the temperature, the physical resistance of the resistor will change. It is usually made up of ceramic materials like manganese, oxides of nickel, cobalt coated glass and other materials.