Jun 03, 2021 Thermostat
A thermostat is a device to detect temperature changes for the purpose of maintaining the temperature of an enclosed area essentially constant. In a system including relays, valves, switches, etc., the thermostat generates signals, usually electrical, when the temperature exceeds or falls below the desired value. It usually is used to control the flow of fuel to a burner, or electric current to a heating or cooling unit, or of a heated or cooled gas or liquid into the area it serves. The thermostat is also an element in some types of fire-detection warning systems. Thermostat work by using the fact that most things get bigger when they heat up and smaller when they cool down. Mechanical thermostats use this idea to switch an electric circuit on and off. The two most common types use bimetallic strips and gas-filler bellows.
A traditional thermostat has two pieces of different metals bolted together to form what's called a bimetallic strip (or bimetal strip). The strip works as a bridge in an electrical circuit connected to your heating system. Normally the "bridge is down", the strip carries electricity through the circuit, and the heating is on. When the strip gets hot, one of the metals expands more than the other so the whole strip bends very slightly. Eventually, it bends so much that it breaks open the circuit. The "bridge is up", the electricity instantly switches off, the heating cuts out, and the room starts to cool.
As the room cools, the strip cools too and bends back to its original shape. Sooner or later, it snaps back into the circuit and makes the electricity flow again, so the heating switches back on. By adjusting the temperature dial, you change the temperature at which the circuit switches on and off. Because it takes some time for the metal strip to expand and contract, the heating isn't constantly switching on and off every few seconds, which would be pointless
An alternative design of a thermostat senses temperature changes more quickly using a pair of metal discs with a gas-filled bellows in between. The discs have a large surface area so they react quickly to heat and they're corrugated to make them springy and flexible. When the room warms up, the gas in the bellows expands and forces the discs apart. The inner disc pushes against a microswitch in the middle of the thermostat turning the electric circuit off. As the room cools, the gas in the bellows contracts and the metal discs are forced back together. The inner disc moves away from the microswitch, switching on the electric circuit and turning the heating on again. A Wax thermostat is the most common example that uses the change in the state of a substance from liquid to gas to work. They use a little plug of wax inside a sealed chamber. As the temperature changes, the wax melts (changes state from solid to liquid), expands greatly and pushes a rod out of the chamber that switches something on or off. Wax thermostats tend to be more reliable and longer-lasting in the extreme conditions inside a vehicle engine.
Thermostat is available through Quick Time Engineering Inc.
Quick Time Engineering Inc is an international company with offices and distribution networks in the USA, Hong Kong, Europe and Malaysia.
In its 20 years of operation since 1998, Quick Time Engineering Inc had emerged from a local engineering company with a single staff that provided solutions in factory automation to become nowadays a company that serves the Oil & Gas industries, EPC contractors, System Integrators and other industrial automation and process control companies worldwide. Customers from over 50 countries worldwide trust us with their need for process control instruments and industrial automation products.
For more information about Quick Time Engineering Inc, visit www.quicktimeonline.com or email enquiry@quicktimeonline.com
