SU401897A1 - FURNACE FOR CHECKING THERMAL SENSORS - Google Patents

Description

one

The invention relates to a measurement technique and can be applied in all parts of the national economy, where temperature sensors are used and calibrated to measure temperatures.

A well-known furnace for calibration of temperature sensors, comprising a stationary metal unit installed in a vertical position with blind chambers arranged concentrically with respect to the axis of the block and serving to accommodate a temperature sensor, a partitioned heater and a set of interchangeable bushings.

The proposed furnace differs from that known in that the block with chambers for accommodating thermal sensors is made in the form of separate sections installed at equal distances from the axis of the block as well as from each other. This reduces the inertia of the furnace and its weight.

FIG. 1 shows the proposed furnace; in fig. 2 - interchangeable bushings.

The furnace consists of a vertically arranged partitioned metal block 1, each section is provided with a blank chamber 2 with a conical bottom plate. Chambers 2 serve to install in them potable and exemplary thermal sensors. When calibrating temperature sensors having different immersion depths, a set of interchangeable sleeves 3 is installed in chambers 2 with a corresponding depth of the internal cavity. The inner cavity of the sleeve 3 performs the function of chambers 2. Inside the block 1 a metal core 4 is mounted. It has the shape of rolls, between the flange 1 and which the sections of the heating element 5 are concentrically arranged to create a uniform temperature field in the installation zone of the block 1. The sections of the heater are interconnected in series in two parallel groups n have trn output ends 6 connected to the thermostat via a special switch (not shown) to enable parallel and sequential switching, depending on the set temperature. To control the temperature in the zone of heating elements 5 n automatic stabilization of temperature in chambers 2 a thermocouple 7 is installed in this zone, the cold ends 8 of which are connected to the thermostat. For reflected heat rays on the upper and lower disks of the block 1, a metal screen 9 is installed.

To ensure the alignment of the axes of the core 4n block I with the axis of the furnace, pin 10 is installed in the bottom part of the housing.

To provide vertical thermocouples located in chambers 2 (or in interchangeable

bushings 3) the furnace is equipped with a removable centering device 11.

The furnace in the radial direction is thermally insulated by quartz cylinders 12 concentrically located about the furnace axis, and in height - by heat insulating plates 13 and 14, with the top plate 13 made detachable to facilitate dismantling and mounting of the core 4 when changing heaters.

When calibrating, for example, thermocouples, they are installed (simultaneously with the model one), one in each chamber 2. The cold ends of the thermocouples and the model thermocouples are connected by a compensation wire to the measuring device (not shown in the drawing) through a multipoint switch. Each thermocouple is assigned a sequence number. The temperature limiter on the thermostat establishes a predetermined temperature in the zone of the chambers, taking into account the constant temperature difference between the heating elements 5 and the chamber 2 of the unit 1, which is determined after the manufacture of the furnace. The temperature on the heating elements is automatically maintained by the thermostat, which ensures the stabilization of the set temperature in chambers 2 during the entire calibration period. The moment of reaching the set temperature and its stabilization in chambers 2

is determined by a measuring instrument connected to an exemplary thermocouple installed in one of chambers 2. At the end of the calibration of this set of thermocouples, the following kits are installed in chambers 2. When calibrating temperatures at different temperature conditions, the regimes are changed by shifting the thermostat limiter.

When calibrating temperature sensors with different depths of immersion in chambers 2, a set of bushings 3 is installed with the corresponding depth of the internal cavity.

Subject invention

A furnace for calibration of thermal sensors, containing a metal block stationary installed in a vertical position with deaf chambers arranged concentrically with respect to the axis of the block and serving to accommodate thermal sensors, a sectioned heater and a set of interchangeable sleeves,

characterized in that, in order to reduce the inertia of the furnace and its weight, the metal block with chambers for accommodating thermal sensors is made in the form of separate sections installed at equal distances

from the axis of the block, as well as from each other.

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