Difference between bimetal thermometer and platinum resistance thermometer
The main component of an industrial bimetal thermometer is a multilayer metal sheet composed of two or more metal sheets laminated together. In order to improve the temperature measurement sensitivity, the metal sheet is usually made into a spiral shape. When the temperature of the multi-layer metal sheet changes, the amount of expansion or contraction of each layer of metal varies, so that the spiral coil is rolled up or loosened. Because one end of the spiral coil is fixed and the other end is connected to a pointer that can rotate freely, when the bimetallic piece experiences a temperature change, the pointer can indicate the temperature on a circular indexing scale. The temperature range of this instrument is 200 ~ 650 ℃, and the allowable error is about 1% of the two strokes of the scale. This thermometer is similar to a rod-shaped glass liquid thermometer in use, but can be used under conditions that require higher mechanical strength. WSS series bimetal thermometer is a kind of on-site detection instrument suitable for measuring medium and low temperature. It can be used to directly measure the temperature of gas, liquid and steam. The thermometer is waterproof, corrosion-resistant, vibration-resistant, intuitive and easy to design. Reading, mercury-free, rugged and so on. It can replace other geotechnical temperature measuring instruments and is widely used in petroleum and chemical industry, machinery, shipbuilding, power generation, textile, printing and dyeing industries and scientific research departments.
Bimetal thermometers are manufactured using the principle that different metal sheets pressed together will cause bending due to the different expansion coefficients of the two metals. The greater the temperature change, the more severe the bending. Converting it into a pointer value is a thermometer.
温度计是利用金属铂随温度升高电阻变大的原理制造的，然后经过电子电路转换成可读的值，比双金属温度计有更高的精度。 Platinum thermal resistance thermometers are manufactured using the principle that metal platinum becomes more resistant as temperature increases, and then converted into readable values by electronic circuits, which has higher accuracy than bimetal thermometers.
的精度等级：B级分度号：Pt100 （0℃时的电阻值） Platinum thermal resistance accuracy grade: B grade division number: Pt100 (resistance value at 0 ° C)
R = 100 ± 0.12Ω (B grade)
Allowable deviation: △ t (0C)
± (0.30 ＋ 0.005 | t |) (B grade)
Input: Thermal resistance: Pt100
的输入电阻信号成线性，与热电阻被测量温度成线性； Output: 4 ～ 20mA DC signal is linear with the input resistance signal of platinum thermal resistance within the range, and linear with the temperature of the thermal resistance being measured;
Note: The input and output of the isolated temperature transmitter are isolated, and the isolation voltage is 0.5KV.
Basic error: calculation formula Δ = Δ1 + Δ2
Δ1 Tolerance deviation of thermal resistance
Δ2 Transmitter basic error ± 0.5% FS
Transmission method: Two-wire transmitter Working power supply: minimum voltage 12V, maximum 35V, rated working voltage 24V
Load: The limit load resistance is calculated as follows:
RL (max) = 50 * (Vmin-12)
(That is, at 24V, the load resistance can be selected in the range of 0 to 600Ω, and the rated load is 250Ω)
a) Ambient temperature: －250C ～ 800C (not more than 70 ℃ in dangerous places)
b) Relative humidity: 5% to 95%
c) Mechanical vibration: f≤55Hz, amplitude <0.5mm
d) The surrounding air does not contain any medium that causes the transmitter to corrode