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The double metal thermometer is a kind of field testing instrument for measuring low and medium temperature. Can be directly measured in various production process of -80 C C -+500 C range of liquid vapor and gas medium temperature. Industrial bimetal thermometer main element is a with two or more metal sheet stack pressure in together to form a multilayer metal sheet, the use of two different kinds of metal in the change of the temperature of expansion degree of different working principle. The composition of the double metal sheet which is based on the loop winding. At one end of the heating expansion, led to the rotation of the pointer, the working instrument will show the temperature value of the thermal electric potential.
WSS series double metal thermometer is a kind of low temperature measurement of field testing instrument. The double metal thermometer can directly measure the temperature of liquid, vapor and gas medium in the range of -80.
Principle structure
Bimetallic thermometer is around a screw shaped thermal dual metal sheet as a temperature sensing device, and put it in a protective sleeve, one end fixed, is a fixed end and at the other end of the connection in a small shaft, a free end. A pointer in the free end of the shaft. When the temperature is changed, the free end of the temperature sensing device rotates and drives the pointer on the fine shaft to produce the angle change, and the corresponding temperature is indicated on the scale plate.
Selection notice
classification
According to the connection direction of the dual metal thermometer and the protection tube, the double metal thermometer can be divided into four types, including axial type, radial type, 135 degree direction type and universal type.
Axial type double metal thermometer: the pointer plate and the vertical connection of the protection tube.
Radial type double metal thermometer: the pointer plate and the protective tube parallel connection.
135 degree to type double metal thermometer: the pointer plate and the protection tube into 135 degrees connection.
The universal type double metal thermometer: pointer disc and the protective tube is connected with the angle adjustable.
Fixed form
In order to adapt to the need of actual production, double metal thermometer has different forms of fixed installation: movable external screwed pipe joint, movable inner threaded pipe joint, screw thread joint, a clamping sleeve threaded joint, flange joint and a fixing flange card.
Model name
W S S sign - protection form
No ordinary type
Installation of fixed W- protection type
0- anti corrosion type of F- non fixing device
Structure form 1- movable external screw thread
0- axial type 2- movable inner screw thread
1- radial 3- fixed screw thread
2-135 degree to type 4- fixed screw thread
3- universal 5- card sleeve screw thread
Nominal diameter flange 6- card case
The diameter of 60 3-
The diameter of 100 4-
The diameter of 125 5-
The temperature sensing element is a double metal
Metal expansion
Temperature instrument
characteristic
The double metal thermometer has the advantages of fast response, small size, good linearity and stability. Some foreign products have high temperature working performance.
The thermoelectric power of a bimetallic thermometer is only related to the thermoelectric properties of the thermoelectric materials and the temperature difference between the two ends. The same kind of homogeneous conductor or semiconductor is used to form a loop, and it will not generate the thermal electric potential.
Thermocouple two contact temperature T0, T, if T=T0, thermocouple thermoelectric potential is zero. The law of intermediate temperature lays the foundation for the development of thermocouple dividing table.
Relationship between for many years, scientists have tried to study can function even with piecewise function to express the thermocouple hot end measuring temperature with a thermocouple loop of the thermopower, ultimately did not succeed.
If two conductor, a B respectively and the third conductor compositions thermoelectric has a wide temperature range, long-term use of stable physical and chemical properties of high conductivity, small temperature coefficient of resistance; thermopower] configuration has higher sensitivity, thermo electromotive force and temperature is linear between, easy to copy, process is simple, the price is cheap. But the misuse of compensation bridge supporting nickel chromium nickel silicon, the balance compensation of the bridge 0 degrees C. When the cold end temperature is 30 degrees C, the thermometer indicates temperature 900 degrees C, the actual temperature of the heating furnace? To use the law of standard electrode to determine the element with the change of the temperature.
General double metal thermometer used in low temperature, thermocouple used in high temperature. If the temperature exceeds 500 degrees so the resistance of the double metal thermometer will be very large, may affect the measurement results and may even appear not to be out of measurement results.
