JP2014211386A - Thermostatic chamber for chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermostatic chamber provided for chromatograph in which no or little overshoot is generated.SOLUTION: A thermostatic chamber 200 is provided with a temperature controller 60 that comprises: a temperature converter 61 that is connected to a temperature sensor 50 and outputs a value indicating air temperature in a housing 10; a temperature control circuit 62 in which the air temperature in the housing output by the temperature converter is regarded as a controlled variable, a target temperature of air in the housing is regarded as a setting value, the amount of heat generated by a heater 30 is regarded as a manipulated variable, and control is performed based on P control, PI control, or PID control; a control parameter setting circuit 63 that instructs the temperature control circuit with a proportional gain and/or an integral gain on the basis of the target temperature of air in the housing and the air temperature in the housing output by the temperature converter; and a power-supply circuit 64 that supplies power to the heater on the basis of the amount of heat generated by the heater that is output from the temperature control circuit.

Description

  The present invention relates to a thermostatic chamber for controlling the temperature of a mobile phase supply unit, a sample introduction unit, a separation column, a detection unit and the like provided in a chromatograph. In particular, the present invention relates to a thermostatic chamber provided in a chromatograph capable of analyzing in a wide temperature range from a temperature of about room temperature plus 10 ° C. to a temperature of about room temperature plus 200 ° C.

  Among the chromatographs, the liquid chromatograph includes a mobile phase (eluent) supply means, a sample introduction means, a separation column, a detection means, a waste liquid container, and a flow path connecting them. When the sample is introduced upstream of the separation column by the sample introduction means in order to analyze the components contained in the sample, the sample is introduced into the separation column by the eluent supplied from the eluent supply means. The liquid chromatograph uses the fact that the time to pass through the separation column differs for each component in the sample, and the detection means for separating the component contained in the sample and providing the component eluted from the separation column downstream of the separation column After detection, discard the eluate in a waste container. Note that the eluate can be collected in a plurality of containers without being discarded in a waste liquid container, or discarded in a waste outlet.

  In the analysis by liquid chromatography, the temperature of the sample introduction means and separation column can be increased for the purpose of improving the component separation ability in the sample by the separation column and improving the solubility of the component in the sample. Done. In addition, since the eluent supply stability by the eluent supply means, the peak retention time by the separation column, the signal baseline by the detection means, and the like depend on the temperature, the temperature is adjusted as necessary. Therefore, the eluent supply means, the sample introduction means, the separation column, and the detection means are stored individually or in a plurality of means in a constant temperature bath and held at a constant temperature (heated as necessary).

  A constant temperature bath that maintains at least one of the mobile phase supply means, sample introduction means, separation column (separation means), and detection means provided in the chromatograph is usually one of the above means. A housing for housing, a heater for heating the air in the housing, and a fan for circulating the air in the housing; and circulating the air heated by the heater through the fan The temperature inside the casing is kept constant. In the case where no cooling means is provided in the thermostatic bath, temperature control is usually possible if the target temperature of the case air is set 10 ° C. or more higher than the air temperature outside the case. In the case of a synthetic polymer that is not easily dissolved in a solvent such as engineering plastics, the chromatographic measurement target may be heated to 200 ° C. or higher. In that case, wrap the case with a thick heat insulating material to improve the heat insulating performance. Strengthen.

  In the above-described thermostatic chamber, the air temperature in the housing is measured (control amount), and the heating value of the heater is controlled so that the air temperature becomes a predetermined temperature (set value) (when an electric heater is used as the heater) Controls the power supplied to the heater. As a method of controlling the amount of heat generated when an electric heater is used as the heater, normally, P control (proportional control) for supplying the electric heater with electric power (proportional term) proportional to the difference between the set value and the control amount, or a set value PI control that supplies electric heaters with power (proportional term) that is proportional to the difference between the control value and the control amount, and power (integral term) that is proportional to the integral value with respect to the time of the difference between the set value and the control amount. In addition to the power proportional to the difference between the control amount and the power (proportional term) and the power proportional to the integral value (integral term) of the difference between the set value and the control amount, PID control is used to supply proportional power (differential term) to the electric heater. In PI control and PID control, the integral term causes overshoot (overshoot) after starting temperature regulation and reaching the target temperature, and in many cases, the controlled variable reaches a temperature near the set value. It is reset when

  In the above-described constant temperature bath, there is a problem that overshoot (overshoot) is likely to occur because the speed at which the heat of the heater is transmitted to the air is slow. In particular, when the set temperature in the housing is greatly changed from a temperature close to the air temperature outside the housing (environmental temperature) to a temperature about 200 ° C. higher than room temperature, a heater having a heat generation amount necessary to raise the temperature to the high temperature It is necessary to provide heat insulation performance of the housing. In that case, if the temperature of the air in the housing is set to a temperature close to the environmental temperature, the overshoot continues for a long time even if the integral term is reset.

  In order to solve the above problem, there is a method in which the amount of heat generated by the heater is changed by replacing the heater or changing the supply voltage depending on the set temperature of the air in the housing. However, it takes time to replace the heater with an optimum heater or to change to an optimum supply voltage.

  Accordingly, an object of the present invention is to provide a chromatograph provided with a mobile phase supply means, a sample introduction means, a separation means, and a detection means, and a casing that houses any one or more of the means, and the casing. A thermostat bath having a heater for supplying heat to the air in the body and a fan for circulating the air in the housing to control the temperature of any one or more of the above means, with no or little overshoot Is to provide.

  This invention made | formed in view of the said subject includes the following aspects.

That is, the first aspect of the present invention is:
Provided in a chromatograph including a mobile phase supply means, a sample introduction means, a separation means, and a detection means, and a case that houses any one or more of the means, and supplies heat to the air in the case Any of the above-mentioned means comprising: an electric heater that detects the temperature of the air in the housing; a temperature controller that controls the air temperature in the housing; and a fan that circulates the air in the housing. Or a thermostat that regulates the temperature of one or more of the temperature regulators,
A temperature converter connected to the temperature sensor and outputting a value indicating the air temperature in the housing;
The air temperature in the housing output from the temperature converter is set as a control amount, the target temperature of the air in the housing is set as a set value, the heat generation amount by the heater is set as an operation amount, and proportional control (P control), proportional-integral control ( A temperature control circuit that performs control based on (PI control) or proportional-integral-derivative control (PID control);
A control parameter setting circuit for instructing the temperature control circuit of a proportional gain and / or an integral gain based on the target temperature of the air in the housing and the air temperature in the housing output by the temperature converter;
A power supply circuit that supplies power to the heater based on the amount of heat generated by the heater output from the temperature control circuit;
It is the said thermostat which had.

  According to a second aspect of the present invention, the control parameter setting circuit sets the proportional gain and / or integral gain to a temperature based on a difference between the target temperature of the air in the housing and the air temperature in the housing output by the temperature converter. It is a thermostat as described in said 1st aspect which is a circuit which instruct | indicates to a control circuit.

  Hereinafter, the present invention will be described in detail.

  The constant temperature bath of the present invention is a chromatograph for maintaining (temperature controlling) one or more of mobile phase supply means, sample introduction means, separation means (separation column), and detection means at a constant temperature. Provided.

  As the heater provided in the thermostat for the chromatograph, an electric heater that directly transfers heat to the air in contact with the heater is often used. The electric heater can control the amount of heat generated by the amount of electric power applied. Electric heaters use the heat generated by semiconductor elements such as heaters with spiral or spiral wound wires, heaters sealed in tubes made of metal (for example, stainless steel), glass or ceramics, and power transistors. There are known heaters and PTC heaters made of semiconductor ceramic, but any heater may be used. Of the electric heaters described above, when using a heater sealed in a stainless steel cylinder, providing fins on the outside increases the amount of air that contacts the heater, which improves heat transfer to the air inside the housing. ,preferable. If a power transistor is used, it may be attached to a heat sink or the like. One or more electric heaters may be provided in the thermostatic chamber.

  The thermostat of the present invention has a temperature sensor that detects the air temperature in the housing. Since the temperature of the air temperature varies depending on the position in the casing, the temperature of each means (for example, mobile phase supply means such as a liquid feed pump or a separation column) accommodated in the casing and the location where the sensor is installed It is preferable to provide it at a position where the difference from the air temperature is small and the wind is well. Examples of the temperature sensor that can be used for the temperature sensor include a platinum resistance thermometer, a thermocouple, a thermistor, and the like, and may be appropriately selected according to the temperature range to be used. Since the temperature sensor measures the air temperature, it is preferable to use a small sensor with good time response. The material used for covering the lead wire of the temperature sensor may be appropriately selected from vinyl chloride, polyethylene, fluororesin, glass fiber, ceramic, etc. according to the temperature range to be used.

  Among the temperature regulators provided in the thermostat of the present invention, the temperature converter can be selected from known temperature converters according to the type of temperature sensor used. When a platinum resistance thermometer or thermistor is used as a temperature sensor, it is usually incorporated into one side of a Wheatstone bridge connected to a constant current power source or a constant voltage power source, and a temperature signal is obtained by amplifying the potential difference between the two midpoints. If the nonlinearity between the temperature and the temperature signal is large, a correction circuit may be further used. When using a thermocouple as the temperature sensor, provide a temperature measuring contact and a cold junction (reference contact) that detect the temperature, and keep the cold junction at a predetermined constant temperature, for example, the triple point temperature of water. What is necessary is just to amplify the potential difference between the lead wires consisting of. Instead of keeping the cold junction at a constant temperature, the temperature of the cold junction may be measured to compensate for the potential difference.

Among the temperature regulators provided in the thermostatic chamber of the present invention, the temperature control circuit controls the air temperature in the casing output from the temperature converter connected to the temperature sensor that detects the air temperature in the casing. The circuit is a circuit in which the target temperature of the air in the housing is set to a set value (SV) and the amount of heat generated by the electric heater is the manipulated variable (MV), and is controlled by either proportional control (P control), PI control or PID control To do. In PID control, if the proportional gain is Kp, the integration time is Ti, and the derivative time is Td,
MV = Kp × {(PV−SV) + ∫ (PV−SV) dt / Ti + d (PV−SV) / dt × Td}
It is represented by Here, if the set amount is constant, the third term in parentheses may be expressed as dPV / dt × Td. In the PI control, Td = 0, and in the P control, Td = 0 and Ti = ∞. In the temperature control circuit in the thermostat according to the present invention, an integral gain Ki (= Kp / Ti) and a differential gain Kd (= Kp · Td) are used instead of the integral time (Ti) and the derivative time (Td). These control parameters may be appropriately determined so that the air temperature is stabilized.

  Among the temperature regulators provided in the thermostat according to the present invention, the control parameter setting circuit sets the proportional gain and / or integral gain to the temperature based on the target temperature in the casing and the air temperature in the casing output from the temperature converter. This is a circuit for instructing the control circuit, and at least when the heat is supplied to the air in the housing by the electric heater (at the time of temperature rise), the proportional gain and / or integral gain decreased from the steady state can be instructed to the temperature control circuit Circuit. If the difference between the target air temperature inside the housing and the air temperature outside the housing is small, if the amount of heat generated by the electric heater is large, the electric heater generates heat after the air temperature inside the housing reaches the target temperature of the air inside the housing. Even after cutting, the temperature continues to rise (overshoot). Therefore, overshoot can be reduced by reducing the amount of heat generated by the electric heater. The amount of heat generated may be reduced from the beginning, but if the amount of heat generated is reduced when the air temperature in the housing approaches the target temperature of the air in the housing, the temperature can be raised to the target temperature of the air in the housing in a short time. Therefore, it is preferable. As an example, when the air temperature in the housing reaches a temperature that is 10 ° C., 15 ° C., or 20 ° C. lower than the target temperature of the air in the housing, the amount of heat generated by the electric heater is reduced, that is, lower than the steady state. The proportional gain and / or integral gain may be indicated to the temperature control circuit. Further, in addition to these instructions, a differential gain that has decreased from the steady state may be instructed to the temperature control circuit. For example, the proportional gain and / or the integral gain may be decreased stepwise in one step, two steps, or three steps, or may be decreased continuously. In the case of stepwise or continuous reduction, for example, the reduction may be performed based on the difference between the target temperature of the air in the housing and the air temperature in the housing output by the temperature converter. The value of the proportional gain after being lowered may be determined in consideration of the overshoot and the heating rate. As an example, it can be used as the value of the proportional gain after a value obtained by multiplying the proportional gain at the time of 0.005 by 0.005 is lowered.

  The proportional gain and / or integral gain instructed to the temperature control circuit by the control parameter setting circuit is, for example, a temperature (or 15 ° C.) lower than the target temperature of the air in the housing by 10 ° C. after the temperature control is started. Until the temperature reaches a low temperature (20 ° C. lower temperature), the proportional gain and / or integral gain in the steady state is indicated, and the temperature of the air in the housing is 10 ° C. lower than the target temperature of the air in the housing (or 15 ° C. lower) Until the target temperature of the air in the housing is reached from the temperature 20 ° C.), the proportional gain and / or the integral gain lower than those in the steady state may be indicated. In addition, after the air temperature in the housing reaches the target temperature of the air in the housing, it may be instructed to return to the proportional gain and / or integral gain in the steady state. In addition, when the target temperature of the air in the housing is raised once the air temperature in the housing reaches a steady state, the proportional gain and / or integral gain instructed to the temperature control circuit by the control parameter setting circuit is, for example, As in the case of starting the temperature control, after raising the target temperature of the air in the housing, the air temperature in the housing reaches a temperature that is 10 ° C. lower than the target temperature of the air in the housing (or a temperature that is 15 ° C. lower or 20 ° C. lower). Until, the proportional gain and / or integral gain in the steady state is instructed, and the air temperature in the housing is 10 ° C. lower than the target temperature of the air in the housing (or 15 ° C. lower temperature, 20 ° C. lower temperature). Until the target temperature is reached, the proportional gain and / or the integral gain reduced from the steady state may be indicated.

  In order to change the electric power applied to the electric heater based on the amount of heat generated by the electric heater output from the temperature control circuit, the current or voltage flowing through the heater is changed to a transistor or FET (field effect transistor), as is generally known. The power may be adjusted by continuously changing the power by switching the current or voltage at regular intervals using a switching device such as a transistor, FET, or thyristor, and changing the duty ratio. May be adjusted. A DC power supply may be used, or an AC power supply may be used.

  The constant temperature bath of the present invention includes a casing that houses any one or more of a mobile phase supply means, a sample introduction means, a separation means, and a detection means, an electric heater that supplies heat to the air in the casing, and the casing. A temperature sensor that detects an air temperature in the body, a temperature regulator that controls the air temperature in the housing, and a fan that circulates the air in the housing; and the temperature regulator serves as a temperature sensor. A temperature converter connected to output a value indicating the air temperature in the housing, and a heat generated by the heater using the air temperature in the housing output by the temperature converter as a control amount and a target temperature of the air in the housing as a set value A temperature control circuit that performs control based on proportional control (P control), proportional-integral control (PI control), or proportional-integral-derivative control (PID control) using the amount as an operation amount, and a target temperature and temperature conversion of the air in the housing In the case output by the instrument A control parameter setting circuit for instructing the temperature control circuit on the proportional gain and / or integral gain based on the air temperature, and a power supply circuit for supplying power to the heater based on the amount of heat generated by the heater output from the temperature control circuit, It is characterized by having.

  The thermostat of the present invention is a thermostat that has little or almost no overshoot of the air temperature inside the housing with respect to the target temperature of the air temperature inside the housing in the control of the air temperature inside the housing by the thermostat, and the air inside the housing is short. The target temperature can be reached in a timely and stable manner. That is, since the time from the start of control of the air temperature in the housing by the electric heater to the time when the analysis by the chromatograph becomes possible is shortened, the waiting time is reduced and the use efficiency of the chromatograph can be improved. .

The figure which shows the one aspect | mode of the conventional thermostat. The figure which shows the one aspect | mode of the thermostat of this invention. The figure which shows the result of the comparative example 1. The figure which shows the result of the comparative example 1. FIG. 4 is a diagram showing the results of Example 1. FIG. 4 is a diagram showing the results of Example 1. The figure which shows the result of Example 2. FIG. The figure which shows the result of Example 2. FIG.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using a comparative example and an Example, these examples do not limit this invention.

Comparative Example 1
An attempt was made to control the air temperature in the housing with an electric heater using the conventional thermostat shown in FIG.

  A conventional thermostat 100 shown in FIG. 1 includes a housing 10 for housing the separation column 20, an electric heater 30 for supplying heat to the air in the housing, and a fan for circulating the air in the housing. 40, a temperature sensor 50 for detecting the air temperature in the housing, and a temperature regulator 60 for controlling the air temperature in the housing. The temperature regulator 60 is connected to the temperature sensor 50 and outputs a value indicating the air temperature in the housing. The temperature regulator 60 uses the air temperature in the housing output from the temperature converter 61 as a control amount. A temperature control circuit 62 that uses a target temperature of air as a set value and an amount of heat generated by the electric heater 30 as an operation amount, and a power supply circuit that supplies electric power to the electric heater 30 based on the amount of heat generated by the heater output from the temperature control circuit 62 66.

  The capacity | capacitance of the housing | casing 10 is 30L, and is thermally insulated with respect to external air with the heat insulating material of thickness 20mm. The temperature sensor 50 uses a small platinum resistance temperature sensor. A detection result by the temperature sensor 50 is converted into a temperature signal 71 by a temperature converter 61 including a constant current power source, a voltage amplifier, and a correction circuit, and is input to the temperature control circuit 62. The temperature control circuit 62 performs control based on PI control. The temperature control circuit 62 inputs the temperature signal 71 and the target temperature (set value instruction signal 72) of the air in the housing, and outputs a voltage signal (heat generation amount instruction signal 73) corresponding to a duty ratio of 0 to 1. The electric power supply circuit 64 supplies electric power 74 to the electric heater 30 only during a period of 2 seconds in a cycle of 2 seconds, and cuts off the electric power supply for the remaining time (proportional ON / OFF control). The average power supplied to the electric heater 30 is proportional to the duty ratio, and is 400 W when the duty ratio is 1.

  In the temperature control circuit 62, the proportional gain Kp is set to 1, the integral gain Ki is set to 1/250, and the differential gain Kd is set to 0 (for PI control). The integral term of PI control in the temperature control circuit was reset to zero when the temperature reached and when the changed target temperature was reached for the first time after changing the target temperature of the air in the housing.

  FIG. 3 shows an example of a temperature pattern when the air temperature outside the housing is 25 ° C., and the target temperature of the air inside the housing is initially 45 ° C. and changed to 55 ° C. after 100 minutes (6000 seconds), FIG. 4 shows an example of a temperature pattern when the air temperature outside the housing is 25 ° C. and the target temperature of the air inside the housing is initially changed to 45 ° C. and 150 ° C. after 80 minutes (after 4800 seconds). In particular, it can be seen that a large overshoot continues for a long time when the target temperature of the air in the housing is low and the difference in the air temperature outside the housing is small (FIG. 3).

Example 1
Using the thermostat of the present invention shown in FIG. 2, an attempt was made to control the air temperature in the housing with an electric heater.

  The thermostat 200 shown in FIG. 2 includes a temperature converter 61 in which the temperature regulator 60 is connected to the temperature sensor 50 and outputs a value indicating the air temperature in the housing, and the temperature of the thermostat shown in FIG. A temperature control circuit 62 for controlling the air temperature in the housing output from the converter 61 as a control amount, a target temperature of the air in the housing as a set value, a heat generation amount by the electric heater 30 as an operation amount, and controlling based on PI control; A control parameter setting circuit 63 for instructing the temperature control circuit 62 on the proportional gain and the integral gain based on the air temperature in the housing output from the vessel 61 and the target temperature of the air in the housing, and the electric heat output from the temperature control circuit 62 The regulator includes a power supply circuit 64 that supplies power to the electric heater 30 based on the amount of heat generated by the heater 30.

  The temperature control circuit 62 compares the temperature signal 71 output from the temperature converter 61 with the target temperature (set value temperature signal 72) of the air in the housing, and instructs the amount of heat generated by the electric heater 30 based on PI control. A signal 73 is output. The power supply circuit 74 supplies 74 power to the electric heater 30 based on the heat generation amount instruction signal 73.

The proportional gain Kp and integral gain Ki instructed from the control parameter setting circuit 73 to the temperature control circuit 72 are:
Kp is set to 1 and Ki is set to 1/250 until the air temperature in the housing reaches a temperature 10 ° C. lower than the target temperature of the air in the housing after the temperature control is started.
Then, until the air temperature in the housing reaches the target temperature of the air in the housing, set Kp to 0.005 and Ki to 0.005 / 250,
After the air temperature in the housing reached the target temperature of the air in the housing, Kp was set to 1 and Ki was set to 1/250. Since the temperature control circuit 62 in the thermostat 200 shown in FIG. 2 controls the temperature by PI control, the differential gain Kd is always zero. Also, the integration of PI control in the temperature control circuit when the air temperature in the housing first reaches the target temperature of the air in the housing for the first time and when the target temperature of the air in the housing is changed and reaches the changed target temperature for the first time. The term was reset to zero.

  FIG. 5 shows an example of a temperature pattern when the air temperature outside the housing is 25 ° C. and the target temperature of the air inside the housing is initially 45 ° C. and changed to 55 ° C. after 100 minutes (6000 seconds later). FIG. 6 shows an example of a temperature pattern when the air temperature outside the housing is 25 ° C. and the target temperature of the air inside the housing is initially changed to 45 ° C. and 150 ° C. after 80 minutes (after 4800 seconds). It can be seen that overshoot is reduced compared to the temperature pattern in the case where the conventional thermostatic bath shown in FIG. 1 is used (Comparative Example 1) regardless of the set temperature.

Example 2
The proportional gain Kp and the integral gain Ki instructed from the control parameter setting circuit 73 to the temperature control circuit 72 are
Kp is set to 1 and Ki is set to 1/250 until the air temperature in the housing reaches a temperature 10 ° C. lower than the target temperature of the air in the housing after the temperature control is started.
Then, Kp is set to 0.02 and Ki is set to 0.02 / 250 until the air temperature in the housing reaches the target temperature of the air in the housing.
After the air temperature in the housing reaches the target temperature of the air in the housing, Kp is set to 1 and Ki is set to 1/250, respectively. I tried to control the temperature.

  FIG. 7 shows an example of a temperature pattern when the air temperature outside the housing is 25 ° C., and the target temperature of the air inside the housing is initially 45 ° C. and changed to 55 ° C. after 100 minutes (6000 seconds), FIG. 8 shows an example of a temperature pattern when the air temperature outside the housing is 25 ° C., and the target temperature of the air inside the housing is initially 45 ° C. and changed to 150 ° C. after 80 minutes (after 4800 seconds). Similar to the case of Example 1, it can be seen that the overshoot is reduced compared to the temperature pattern in the case of using the conventional thermostatic bath shown in FIG. 1 (Comparative Example 1) regardless of the set temperature. .

  The present invention can be set in an air circulating thermostat housing any one or more of mobile phase supply means, sample introduction means, separation means, and detection means, since the temperature rise characteristics and response to disturbance are improved. This is particularly useful for chromatographs that require a wide temperature range and high stability and high temperature retention.

100/200: Thermostatic bath 10: Housing 20: Separation column 30: Electric heater 40: Fan 50: Temperature sensor 60: Temperature regulator 61: Temperature converter 62: Temperature control circuit 63: Control parameter setting circuit 64: Power supply Circuit 71: Temperature signal 72: Set value temperature signal 73: Heat generation amount instruction signal 74: Supply power

Claims (2)

Provided in a chromatograph including a mobile phase supply means, a sample introduction means, a separation means, and a detection means, and a case that houses any one or more of the means, and supplies heat to the air in the case Any of the above-mentioned means comprising: an electric heater that detects the temperature of the air in the housing; a temperature controller that controls the air temperature in the housing; and a fan that circulates the air in the housing. Or a thermostat that regulates the temperature of one or more of the temperature regulators,
A temperature converter connected to the temperature sensor and outputting a value indicating the air temperature in the housing;
The air temperature in the housing output from the temperature converter is set as a control amount, the target temperature of the air in the housing is set as a set value, the heat generation amount by the heater is set as an operation amount, and proportional control (P control), proportional-integral control ( A temperature control circuit that performs control based on (PI control) or proportional-integral-derivative control (PID control);
A control parameter setting circuit for instructing the temperature control circuit of a proportional gain and / or an integral gain based on the target temperature of the air in the housing and the air temperature in the housing output by the temperature converter;
A power supply circuit that supplies power to the heater based on the amount of heat generated by the heater output from the temperature control circuit;
The thermostat having the above. The control parameter setting circuit is a circuit for instructing the temperature control circuit of a proportional gain and / or an integral gain based on a difference between a target temperature of the air in the housing and an air temperature in the housing output by the temperature converter. Item 2. The thermostatic bath according to item 1.

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