Thermistor (thermocouple)

Thermistor (thermocouple)It is a new generation product developed in the Windows environment using the language of the Windows environment. The system is centered around a high-end microcomputer, equipped with a high-precision imported digital multimeter, as well as a measurement and control system consisting of a low potential scanning switch, power regulator, and other components. The operator can easily operate the entire process with a mouse under the Chinese Win95/Win98/WinMe operating system, and the microcomputer system displays the temperature control curve, temperature, and calibration time parameters of the calibration furnace (or oil tank, etc.) in real time.

The system processes data according to the national metrological verification regulations and can print various record forms and verification certificates. It can also retain original records for future reference. The system has achieved full automation of the thermocouple and thermistor calibration process, including automatic temperature control, automatic calibration, automatic data processing, and automatic printing of calibration results. Greatly reducing the labor intensity of operators and improving the quality of calibration work. This device also provides authentication programs and data file management programs for the system, providing convenience for operators to archive, retrieve, and query the authentication and verification results of the system.

The combination of thermal sleeve protection and thermocouple (thermistor) separation is adopted. When in use, users can weld the thermal sleeve protection to the equipment or pipeline, and then install the thermocouple (thermistor) for use. The advantage is that it improves the working pressure and service life of the protective tube, and is convenient for the maintenance and replacement of the thermocouple (thermistor). The thermal sleeve protection tube produced by our factory adopts the technology of integral and deep blind hole processing, and the end of the protective tube does not need to be welded, thereby improving the strength and service life of the thermal sleeve protection tube.

Thermistor (thermocouple)Correct selection of thermocouple thermistor protective sleeve:

1) Selection of Manufacturing Process for Thermocouple Thermistor Sleeve:

There are two processes for making thermocouple thermal resistance sleeves: one is steel pipe welding, and the other is integral drilling.

The welded steel pipe is formed by sealing one end of the steel pipe, and the casing generally has a thin wall and a large inner hole, so the compressive strength is not high, usually only up to 6.4 MPa. If the casing is installed on the pipeline, even if the operating pressure is low, the casing will still break and be damaged under the vibration of impact force due to the high fluid flow velocity. For example, if the casing at the outlet of the circulating water pump is not selected properly, it is prone to damage and even accidents. At the same time, due to the large inner holes of the steel pipes, there are more thermal conductivity intervals inside the casing, resulting in slow measurement response speed. The overall drilling method is formed by drilling solid rod materials, with small inner holes in the casing that closely match the measuring element. Therefore, it has a fast response speed and good anti vibration effect. And it has high compressive strength, reaching over 30MPa. Based on the advantages and disadvantages of the above two processes, it is recommended to use integral drilling casing for the casing process. At present, domestic drilling technology adopts the single end deep blind hole integral drilling process, with a diameter of only Φ 6.5mm for the inner hole of the casing, achieving a perfect fit with the standard Φ 6mm measuring element.

2) Selection of thermocouple thermal resistance sleeve form:

At the same length, conical casing has a higher natural frequency than straight casing, therefore it has stronger resistance to fluid impact and vibration. And because the diameter of the front end of the conical sleeve is thinner than that of the straight sleeve, it ensures a faster reaction speed. Based on the above two points, it is recommended to use a conical casing for the casing form, and the difference in diameter between the large and small ends should not be less than 6mm.

3) Selection of diameter for thermocouple thermal resistance sleeve:

According to the different pressure levels, the diameter of the casing should also be selected reasonably. For example, the diameter of the casing used in medium and low pressure situations can be selected as the diameter of the large and small ends of Φ 25/19mm, and the diameter of the casing used in high pressure situations can be selected as the diameter of the large and small ends of Φ 32/21mm, etc.

4) Selection of installation method for thermocouple thermal resistance sleeve:

There are three installation methods for thermocouple thermal resistance sleeves: flange, thread, and welding.

The welding type is generally determined according to the on-site needs. For both flange and threaded installation methods, it is recommended to use flange installation for the following reasons:

For situations with high pressure levels, threaded installation is not suitable and can only be installed with flanges.

For corrosive environments, threaded installation is prone to corrosion and cannot be disassembled, so flange installation must be chosen.

When used on equipment, flange installation is generally selected.

For situations where the temperature is higher than 230 ℃, threads are prone to high-temperature gap deformation, so flange installation should be selected.

Based on the above points, it is recommended to use flange installation between threads and flanges.