A Method to Reduce the Measurement Error of S - type Thermocouple
S-type thermocouple is a high-precision instrument, but due to the complexity of the operation site environment, and improper operation and other factors, will lead to S-type thermocouple measurement results are biased, we need to find a solution in time to avoid impact Production carried out. Here we introduce to reduce the S-type thermocouple measurement error method, hoping to help everyone to use.
(1) in the mechanical strength of the allowable conditions, as far as possible the choice of small thermal conductivity and diameter of the fine thermal electrode material, the diameter of the hot electrode is usually selected 0.2-0.5 mm.
(2) installation, the child does not destroy the measured surface temperature field and the measured object geometry.
(3) S-type thermocouple measurement side should be measured with the table and a good thermal contact, contact method to the ember good connection (referring to the measured surface to allow welding). Solder joints are not allowed to slag and porous sponge-like, solder joints to be small, at the same time to ensure adequate strength. In order to enhance the S-type thermocouple measurement of the welding strength, the thermal electrode welded part can be slightly flattened.
(4) laying S-type thermocouple, as far as possible to eliminate the interference of convection. For example, in the measured surface of the flow of gas off, in the case of conditions permit, S-type thermocouple is best used buried method. But should pay attention to the size of the slot to be as small as possible after the laying of the surface of the body should be lighting, the measured surface flush, if the measured surface both the flow of gas, and does not allow slotted buried, the laying of thermocouple, Can be installed wing-shaped protective cover or square protective cover (pictured), to reduce the interference of convection.
(5) S-type thermocouple measurement side as close as possible to the measured surface. For the spherical measuring end, the measuring end can be flattened. When the measured thermal conductivity of the object is very small, you can use a good thermal conductivity of the collector.
(6) isothermal laying can effectively reduce the thermal error. The thermal electrode behind the measuring end shall be laid at least 50 times the length of the hot electrode diameter along the surface to be measured. The thermal electrode along the test table should be thin and the thermal conductivity of the material is better to enhance the thermal conductivity between the measured surface and the thermal electrode.
After the hot electrode leads to the measured surface, the thermal electrode insulation layer requires thicker, adiabatic, to reduce the thermal electrode to the airflow heat. If the S-type thermocouple measurement loop resistance is too large, you can take the method of coarse and hot electrode lap, select the thickness of the two thermal electrode lap, pay attention to the thermoelectric properties as consistent.
(7) in the case of change and for instantaneous measurement, the choice of S-type thermocouple dynamic response is better.
(8) thermal electrode material should have good thermoelectric properties, stability and uniformity. Before the production of thermal electrode materials should be tested to ensure that the thermal electrode material performance is good and reliable.
