What is the function of bimetallic thermometer?
This thermometer measures the temperature with the help of a metal probe & a sensor to the end. Thus, this is all about an overview of the bimetallic thermometer. The measurement of temperature is essential in the process of industries like manufacturing, monitoring, safety, health, etc.
How does a bimetallic thermometer work?
How Bimetallic Thermometers work
- View our bimetallic thermometer selection here!
- Table of Contents
- Construction and design. The coefficient of thermal expansion of different metals is different for the same temperature. ...
- Types of bimetallic thermometer. ...
- Selection criteria. ...
- Bimetallic thermometer calibration. ...
- Applications. ...
What does the bimetallic strip do in a thermostat?
Bimetallic strips 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. Eventually, it bends so much that it breaks open the circuit.
How does a bimetallic strip work in a thermostat?
- Bimetallic strips
- How a bimetallic thermostat switches on and off
- Gas-filled bellows
what is a bimetallic stemmed thermometer?
Bimetallic stemmed thermometer is an instrument that uses two different metals to measure temperature. Combine two metals with different coefficients of linear expansion and fix one end. When the temperature changes, the two metals thermally expand differently. Drive the pointer to deflect to indicate the temperature.
What is the most accurate method for calibrating bimetallic thermometers?
1. Fill the container with ice cubes, and then top up with cold distilled water to form a watery slurry.
Bimetallic stemmed thermometer Applications
The bimetal thermometer is an on-site detection instrument for measuring low and medium temperatures. It can directly measure the temperature of liquid, steam and gas medium in the range of -80℃~500℃ in various production processes.
What is the temperature range of a bimetallic stemmed thermometer?
Sino-Inst, Manufacturer for Bimetallic stemmed thermometers, like Digital Thermometer/Transmitter, Digital Thermometer/Transmitter, explosion-proof thermocouple, etc.
What is the working principle of bimetallic thermometer?
The working principle of this thermometer mainly depends on two basic temperature properties of the metal like the following. Once the temperature changes, then there will be a change in the physical dimension of the metals. Whenever the temperature rises, the metal strip turns in the direction ...
What are the two types of bimetallic thermometers?
Types of Bimetallic Thermometer. These thermometers are classified into two types like the spiral strip and helical type. These two thermometers are used to keep the thermometer size in a manageable limit.
How is a helical bimetal thermometer connected?
The helical bimetal is connected at one end in a measuring tube. A metal rod that can be turned in the direction of the helical coil, is connected to another end. A pointer in this thermometer can be connected to the higher side of the metal rod.
What happens when a thermometer is heated?
Whenever the measuring tube is heated up, then the helical bimetal winds up to turn the metal rod. The equivalent temperature will be read off over the calibrated scale. In these thermometers, switch contacts can also be used to close an electrical circuit once the temperature is increased or decreased.
Why is knowing the surroundings of a thermometer important?
Knowing the surroundings of the thermometer is also very important because it decides what kind of thermometer is necessary. The different types of errors that occur while measuring the temperature are convection, conduction, radiation, noise, response time, issues in grounding.
What is thermometer?
Definition: A thermometer which uses two different metal strips for converting the displacement of temperature into mechanical. The metals used in the thermometer are steel, copper & brass. These strips are connected and they will enlarge at different rates once they heated.
Why is a thermometer important?
So temperature detecting device like thermometer plays a key role in the industries due to the reasons like flexible, reliable and economical. The thermometer is one kind of mechanical device, used to measure the temperature rise in different applications using different principles. Measuring the temperature in industries is very important as they ...
What is a bimetallic thermometer?
Bimetallic thermometers are used in residential devices like air conditioners, ovens, and industrial devices like heaters, hot wires, refineries, etc. They are a simple, durable, and cost-efficient way of temperature measurement.
How does a spiral thermometer work?
A spiral-shaped strip is used to measure the temperature in a bimetallic spiral strip thermometer, as seen in Figure 4. As the temperature rises, the two metal strips expand differently. This creates a bending effect and the strip coils in such a way that the metal with a higher thermal coefficient forms the outer side of the arc. As the temperature decreases, the metal with a lower thermal coefficient forms the inner layer of the arc. The pointer and dial attached to the spiral read this deformation which indicates the media’s temperature.
How does a helical strip work?
As the temperature increases, the helical strip senses the temperature change. The strip metal with a higher coefficient of thermal expansion expands and winds up along the stem, rotating the shaft. This rotation causes the pointer to move its position in the dial which indicates the media’s temperature.
Why are spiral strip thermometers used?
Spiral strip thermometers are used in thermostats for their sensitivity to low-temperature variations.
What is the coefficient of thermal expansion of different metals?
The coefficient of thermal expansion of different metals is different for the same temperature. The main component of the bimetallic thermometer is the bimetallic strip. The bimetallic strip consists of two thin strips of different metals, each having different coefficients of thermal expansion. Thermal expansion is the property ...
What is a thermowell?
Thermowells: A thermowell is a cylindrical tube fitting which protects the temperature sensors installed in industrial applications. It acts as a barrier to protect the expensive thermometer from any potential damage from the process fluid.
Can a thermowell be removed?
With a thermowell installed, thermometers can be easily removed and replaced without stopping the process. As the thermowell protects the thermometer, it lasts longer reducing maintenance and replacement costs. Type of thermometer: The bimetallic thermometer can have a helix strip or spiral strip.
HELIX BIMETALLIC THERMOMETER
Fig. 2 Shows Helix bimetallic thermometer, in which, a bimetallic strip is wound in the form of helix. One end of helix is fastened to the casing of bulb and another end is connected to pointer. When the bimetallic helix is heated, difference in thermal expansion of metals causes it to unwound.
SPIRAL BIMETALLIC THERMOMETER
Fig. 3 shows a spiral bimetallic thermometer instrument. Here, the spiral bimetallic (strip) element is attached to the pointer mounted in housing with a scale. When the spiral bimetal is heated, it bends in the direction of metal having ow thermal coefficient of expansion, and rotates in clockwise direction.
Disadvantages of Bimetallic Thermometers
Bimetallic thermometers do not have ability to measure temperatures, which are rapidly changing. Therefore, they are not recommended to use for measurements of fast-changing temperatures.
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What is the purpose of a bimetallic thermometer?
It is used to measure the temperature of the room and to determine the temperature in the refrigerator. #2. Helical Type Bimetallic Thermometer: Helical Type Bimetallic Thermometer is widely used in industries. In some cases, it is necessary to separate the pointer from the bimetallic coil.
What is the working principle of a bimetallic thermometer?
Working Principle of Bimetallic Thermometer: The working principle of a bimetallic thermometer depends on two basic properties of temperature. The metal has the property of thermal expansion, i.e., the temperature-related metal expands and contracts. Not every metal has the same temperature coefficient.
What is a thermometer that rotates in the direction of a helical coil?
A metal rod that can be rotated in the direction of a helical coil is attached to the other end. In this thermometer, a pointer is attached to the top of the metal rod. The helical bimetal wind rotates to rotate the metal rod when the measuring tube is heated. The exact temperature will be read on a calibrated scale.
What is thermometer?
Definition: A thermometer is a device that uses two different metal strips to convert temperature displacement into mechanical. The metals used in the thermometer are steel, copper, and brass. These strips are connected to each other and expand at different rates once heated.
Why is it important to observe the space around a thermometer?
When installing a thermometer it is important to observe the space around it as it determines what type of thermometer we need to use. The various errors that occur when measuring temperature are issues of potential, conduction, radiation, noise, response time, grounding.
Why are thermometers used?
Because they are universal and affordable in price, they are widely used in industry and business. A thermometer is a mechanical device used to measure temperature rise in different applications using a different principle.
Do you separate a thermometer from a bimetallic coil?
In some cases, it is necessary to separate the pointer from the bimetallic coil. It is necessary to keep the temperature measuring sensor in the pipe and the temperature can be displayed on the outside of the pipe. The bimetallic thermometer is made of a bimetal strip and wrapped in a helical coil.
What is a bi-metallic thermometer?
The bi-metallic stemmed thermometer is the most common type of foodservice thermometer. It measures temperature through a metal stem with a sensor in the lower end. The sensing area is from the tip to a half-inch past the dimple. The temperature is read on the dial face. Click to see full answer.
What temperature does a bimetallic thermometer measure?
Thermometer that uses the difference in expansion of two metals (usually iron and brass) to measure temperatures between 30°C or 86°F and 300°C or 375F°; it is used especially in industry.
How to tell if a food thermometer is accurate?
How do I know if my food thermometer is accurate? Insert the thermometer stem at least an inch deep in the ice water without letting the stem touch the glass. Wait for the thermometer to register; this usually takes a minute or less. The thermometer is accurate if it registers 32° F or 0° C.
How often should you calibrate a bimetallic stemmed thermometer?
How often do you calibrate a bimetallic stemmed thermometer? If a thermometer is ever dropped, you should go ahead and calibrate it. If a thermometer is going from a wide variety of temperatures (from freezing temperatures to boiling temperatures), it should also be calibrated more frequently.
What temperature should a thermometer be calibrated to?
A thermometer must be used to monitor food safety temperatures. A metal-stem thermometer with a range of 0°- 220°F is a common choice for food service work- ers. In order to ensure accurate readings, thermometers must be calibrated bi- weekly or monthly, or when dropped or jolted.
How to get a thermometer to read 32 degrees?
Method 1: Ice Water. Fill a glass with ice cubes, then top off with cold water. Stir the water and let sit for 3 minutes. Stir again, then insert your thermometer into the glass, making sure not to touch the sides. The temperature should read 32°F (0°C).
How is a bimetallic strip made?
The bimetallic strip is constructed by bonding together the two thin strips of different metals. Thereby, the length of metals changes at different rates. When the temperature increases, the strip bends towards the metal which has a low-temperature coefficient.
