In order to meet the needs of actual production, bimetallic thermometers have different installation and fixation forms: movable external threaded pipe
Joints, movable inner threaded pipe joints, fixed threaded joints, socket threaded joints, socket flange joints and fixed flanges.
The characteristics of
Bimetallic thermometers have the advantages of fast response, small volume, good linearity and stability
The product also has high temperature performance.
1. The thermoelectric potential of bimetallic thermometers is only related to the thermoelectric properties of the material of the thermal electrode and the temperature difference between the two ends.
2. No thermoelectric potential will be generated by using the same homogeneous conductor or semiconductor to form a circuit.
3. Temperature T,T0, if T=T0, thermoelectric potential of thermocouple is zero.
The law of intermediate temperature is formulated for heat
The electric couple scale laid the foundation.
For many years, scientists have tried to figure out whether a thermocouple's heat can be expressed in terms of functional relations, even piecewise functions
The relationship between the temperature at the end (the measuring end) and the thermoelectric potential produced by the thermocouple circuit, and the final work failed.
5. If two kinds of conductors A, B and the third one respectively constitute thermoelectricity with A wide range of temperature measurement, physical chemistry will be used for A long time
6. High conductivity and low resistance temperature coefficient;
The configured thermoelectric potential is highly sensitive, and the thermoelectric potential is linear to the temperature, which is easy
In replication, the process is simple and cheap.
7. However, the compensation bridge with nickel-chromium-nickel silicon was wrongly used, and its balance point of compensation bridge was 0ºC. When the cold end temperature is
30 & ordm; C, the thermometer indicates temperature 900º C, what is the actual temperature of the furnace? With standard electrodes. Laws to determine the elements that change with temperature.
Bimetallic thermometers are commonly used at low temperatures and thermocouples at high temperatures. If the temperature is over 500 degrees it's double. The resistance of metal thermometers can be very large, which may affect the measurement results and even fail to come out to happen
Generally, bimetallic thermometers are of the following types:
outdoor and heavy
The bimetal thermometer is a field instrument suitable for measuring medium and low temperature. It can be used to measure liquid and gas directly
The temperature of the body.
Main technical parameters: (1) precision grade: 1.5
(2) time constant: J<40S
(3) pressure resistance of protective tube: 6.3mpa
electric contact type
Bimetal thermometer is a kind of field instrument suitable for measuring medium and low temperature. It can be used to measure liquid and gas directly
Main technical parameters (1) precision grade: 1.5
(2) time constant: J<40S
(3) pressure resistance of protective tube: 6.3mpa
(4) contact capacity: rated power: 10VA (non-inductive);
Maximum voltage: ac 220V,
Maximum working current: 1A(non-inductive), connection point is upper and lower limit and normally open.
(5) operating temperature of the head: -25~55 degrees Celsius
Shock - resistant electrical contact bimetal thermometer is a low - and medium-temperature field measurement instrument.
You can measure it directly
In the process of various production - 80 ¡æ ~ + 500 ¡æ within the scope of the liquid, steam and gas medium and severe environment places
And it has a temperature that vibrates.
The shock - resistant electrical contact bimetal thermometer is filled with shock - resistant oil from the inside of the instrument, which can effectively overcome the mechanical vibration
The hands shook.
It is waterproof, corrosion-proof, shock-proof, intuitive, easy to read and mercury-free in design principle and structure
It is widely used in petroleum, chemical industry, machinery, ship, power generation, textile, printing and dyeing
Industry and research.
Main features :(1) on-site display temperature, intuitive and convenient, safe and reliable, long service life;
(2) various structural forms, which can meet different requirements, are free of mercury damage, easy to read, strong and shock-resistant;
(3) the protective pipe material is 1Cr18Ni9Ti stainless steel and molybdenum dititanium, with strong pressure and corrosion resistance;
(4) core-pulling thermometer can not be stopped for short time maintenance or replacement.
Shock - resistant electrical contact bimetallic thermometers are based on a circular bent bimetallic sheet.
One end expands with heat
When the pointer is driven to rotate, the working instrument shows the required temperature value and prevents environmental vibration at the bimetal temperature
The meter is filled with silicone oil or the display part of the bimetal thermometer is separated from the measurement part to achieve the effect of shock resistance.
The shock-resistant bimetallic thermometers are also divided into one-body bimetallic thermometers with shock-resistant contacts and separate shock-resistant contacts
Two types of thermometers.
Main technical parameters: (1) implementation standard: JB/ t8803-1998 gb3836-83
(2) nominal diameter of scale plate: 60, 100, 150
(3) precision grade :(1.0), 1.5
(4) thermal response time: less than or equal to 40S
(5) protection grade: IP55
(6) Angle adjustment error: Angle adjustment error shall not exceed 1.0% of its range
(7) return: the return should not be greater than the absolute value of the basic error limit
(8) repeatability: the repeatability limit should not exceed 1/2 of the absolute value of the basic error limit
Main technical parameters: (1) nominal diameter of scale plate: 100;
(2) precision grade: 1.0, 1.5
(3) connection size: m20x1.5, npt1/2
(4) thermal response time: less than or equal to 40s
(5) protection grade: IP55
Integrated bimetallic thermometer
Integrated bimetallic thermometers are thermometers that transmit heat resistance or thermocouple signals far to function with bimetallic thermometers
Combined with the ground indicating function, it can meet both the demand of field temperature measurement and long-distance transmission
Metal thermometer can be directly measured in the process of various production - 40 ~ + 600 ¡æ within the scope of liquid, vapour and gas
Temperature measurement of body media and solid surfaces.
1. It has the characteristics of small temperature probe, high sensitivity, linear scale and long life.
2. It has a long distance transmission of resistance signal (PT100), shock resistance, corrosion resistance and high power switch signals
Kinds of functions.
3. The structure is the same as that of similar products in the international market and can replace the import.
1, - 40 ~ 600 ¡æ temperature range
2, - 10 ~ 55 ¡æ ambient temperature
3. Relative humidity is less than or equal to 95%
4. Accuracy class 1.5
5. The time constant is less than or equal to 60 seconds
6. Probe pressure resistance is less than or equal to 6Mpa
7. The diameter of the probe is 2008-10mm, and the movable external thread is M27*2
8. Thermal resistance PT100 (single-way, double-way output) or 4-20ma current output
9. Protection grade: IP55
The thermal sleeve type bimetal thermometer can be fitted with various kinds of installation sleeves to meet the requirements of different pressure levels.
You can direct
By measuring various production process - 80 - + 500 ¡æ range of liquid, steam and gas medium, as well as a solid surface
Widely used in petroleum, chemical, metallurgy, textile, food and other industries
For the installation of bimetallic thermometers, attention should be paid to the accuracy of temperature measurement, safety and easy maintenance, and no shadow
The operation and production operation of the ringing equipment shall meet the above requirements when selecting the installation location and insertion depth of the thermal resistance
Note the following points:
(1) in order to allow sufficient heat exchange between the measuring end of thermal resistance and the medium under test, the location of measuring point should be reasonably selected.
Avoid installing thermal resistors near dead ends of valves, elbows, pipes and equipment.
(2) thermal resistance with protective sleeve has heat transfer and heat dissipation loss, in order to reduce measurement error, thermocouple and thermal resistance
There should be enough insertion depth:
for heat resistance temperature center fluid, usually should be measuring end is inserted into the pipe center
(vertical or tilt mounting).
If the pipe diameter of the measured fluid is 200 mm, the thermal resistance is inserted deep
100 mm should be selected;
for high temperature and high pressure and high velocity of temperature measurement (such as main steam temperature), in order to reduce cases of fluid
The resistance of the protective sleeve and the protection sleeve can be broken under the action of fluid
The depth of the shallow-inserted thermal resistance protection sleeve inserted into the main steam pipe shall not be less than 75mm.
The standard insertion depth of the sleeve thermal resistance is 100mm.
if is need to measure the temperature of flue gas, although the flue is 4 m in diameter, thermal resistor insertion depth of 1 m
when measuring the original insertion depth of more than 1 m, shall be installed vertically, as far as possible or add racks and cases tube
Service and maintenance:
1. WSS series bimetallic thermometers should avoid collision protection tube as much as possible during storage, installation, use and transportation.
Do not bend or deform the protective pipe.
It is strictly prohibited to twist the meter case when installing.
2, instrument should be in - 30 ¡æ ~ 80 ¡æ environment temperature in normal work.
3. The temperature at which the instrument often works should be between 1/2 and 3/4 of the scale range.
4. The length of the bimetal thermometer protection tube immersed in the measured medium must be greater than that of the temperature sensing element, and generally the immersion length
More than 100 mm, 0 to 50 ¡æ range in more than 150 mm in length, so as to ensure the accuracy of measurement
5. All kinds of bimetallic thermometers should not be used to measure the temperature of the medium in the open container, and electrified contact thermometers should not be used to work
It is used in the control circuit in the case of large vibration.
6. During the storage, installation and transportation of bimetal thermometers, collision protection pipes shall be avoided and the protective pipes shall not be bent
Change the shape and use the watch as a wrench.
7. The thermometer shall be inspected regularly in normal use.
Generally every six months is advisable.
Working under strong vibration is not allowed to affect the reliability of contact points