The bimetal thermometer is a commonly used thermometer that directly measures the temperature of liquid vapor and gaseous media in the range of -80 °C to +500 °C in various production processes. Users need to have a certain application knowledge in the process of using bimetal thermometers. Today we will introduce the installation points and maintenance methods of bimetal thermometers in detail, and hope to help everyone. Installation points of bimetal thermometer
(1) In order to ensure sufficient heat exchange between the measuring end of the thermal resistance and the measured medium, the position of the measuring point should be reasonably selected to avoid installing thermal resistance near the dead angle of the valve, elbow and pipeline and equipment.
(2) Thermal resistance with protective sleeve has heat transfer and heat loss. In order to reduce measurement error, thermocouple and thermal resistance should have sufficient insertion depth:
a. For the thermal resistance of the fluid temperature in the center of the pipe, the measuring end should normally be inserted into the center of the pipe (vertical or inclined installation). If the diameter of the pipe of the fluid to be tested is 200 mm, the insertion depth of the RTD should be 100 mm;
b. For temperature measurement of high temperature and high pressure and high speed fluid (such as main steam temperature), in order to reduce the resistance of the protective sleeve to the fluid and prevent the protective sleeve from breaking under the action of the fluid, the protective tube may be inserted in a shallow insertion manner or a hot sleeve type. Thermal resistance. The shallow insertion type thermal resistance protection sleeve has a depth of not less than 75 mm inserted into the main steam pipe; the standard insertion depth of the hot sleeve type thermal resistance is 100 mm;
c. If it is necessary to measure the temperature of the flue gas in the flue, even though the flue diameter is 4 m, the thermal resistance insertion depth is 1 m;
d. When measuring the insertion depth of the original more than 1m, it should be installed as perpendicular as possible, or add the support frame and protective sleeve. Maintenance method for bimetal thermometer
1. During the storage, installation, use and transportation of the bimetal thermometer, the collision protection tube should be avoided as much as possible. Do not bend or deform the protection tube. Do not twist the instrument case during installation.
2. The meter should work normally in the ambient temperature of -30 °C ~ 80 °C.
3. The temperature at which the meter works frequently is preferably 1/2 to 3/4 of the scale range.
4. The length of the bimetal thermometer protection tube immersed in the measured medium must be greater than the length of the temperature sensing element. Generally, the immersion length is greater than 100mm, and the immersion length of the 0-50°C range is greater than 150mm to ensure the accuracy of measurement. Bimetal thermometers should not be used in control loops where working vibrations are high.
6. During the storage, installation and transportation of the bimetal thermometer, avoid collision protection tube. Do not bend the protection tube and use the watch as a wrench.
7. The thermometer should be inspected regularly during normal use. Generally every six months is appropriate. The electric contact bimetal thermometer does not allow to work under strong vibrations, so as not to affect the reliability of the contacts.