JPH032843Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is a method to stabilize temperature-sensitive detectors such as differential refractometers and conductivity meters among the detectors used in liquid chromatography. This relates to a constant temperature bath for maintaining the temperature.

(Prior Art) Detectors such as differential refractometers are inherently extremely sensitive to thermal disturbances, and therefore must be used while being housed in a constant temperature bath controlled at a constant temperature.

A conventional constant temperature bath is equipped with a heater and a temperature sensor.
It consists of a heating block surrounded by a heat insulating material on the outside, and a detector such as a differential refractometer is housed in direct contact with the inner surface of the heating block.

(Problem to be solved by the invention) Since the detectors such as differential refractometers housed in the heating block are in direct contact with the heating block, it is difficult to energize the heater to control the heating block to a constant temperature. The pulsations in the temperature of the heating block caused by the on/off of the heating block are transmitted to a detector such as a differential refractometer and appear as noise. Furthermore, it is difficult to completely eliminate drift due to room temperature fluctuations.

As described above, conventional thermostats have a problem in that the output of a detector such as a differential refractometer is not stable.

The purpose of this invention is to improve the stability of the output of a detector such as a differential refractometer by creating a condition in which the detector such as a differential refractometer is not brought into direct contact with a temperature-controlled heating block. It is something.

(Means for solving the problem) The constant temperature bath of the present invention is a heating block that is equipped with a heater and a temperature sensor to control the temperature at a constant temperature, has a hollow interior that forms a liquid/air tank, and is surrounded by a heat insulating material on the outside. A heat insulating member is interposed between the heating block and a detector such as a differential refractometer housed therein, and means for injecting and discharging a liquid with good thermal conductivity into the liquid/air tank in the heating block. This is an attempt to solve the above problems.

(Function) During the period when a detector such as a differential refractometer is heated to the operating temperature, a heat medium made of a liquid with good thermal conductivity such as oil or water is placed between the inner surface of the heating block and the detector such as a differential refractometer. I'll put it in. After reaching the operating temperature,
By removing the heat medium, the inner surface of the heating block and a detector such as a differential refractometer come into contact via a heat insulating member.

(Example) The figure represents one embodiment.

Reference numeral 2 denotes a heating block made of metal with good thermal conductivity, and a heater 4 such as a cartridge heater and a temperature sensor 6 are embedded in the bottom wall surface of the heating block. A heat insulating material 8 surrounds the outer surface of the heating block 2 to prevent thermal disturbances. Reference numeral 10 denotes a differential refractometer as an example of a liquid chromatography detector, which is housed inside the heating block 2 and placed on the bottom surface of the heating block 2 via a plurality of heat insulating legs 12 as heat insulating members. There is. Differential refractometer 1
0 is not in direct contact with the inner surface of the heating block 2.

The internal space of the heating block 2 is a liquid/air tank 14 that can contain liquid.
A funnel-shaped liquid inlet 16 is provided at the top of the liquid/air tank 14 to allow liquid to be injected from the outside, and a liquid outlet 18 is provided at the bottom of the liquid/air tank 14. The liquid inside 14 can be drained. The liquid contained in the liquid/air tank 14 is a heat medium made of a liquid with good thermal conductivity such as oil or water.

To explain the operation of this embodiment, at the time of starting, the liquid drain valve 20 is closed, a heat medium is injected into the liquid/air tank 14 from the liquid injection port 16 to fill it, and the temperature of the heating block 2 is raised by the heater 4. The temperature of the heating block 2 is detected by a temperature sensor 6, and becomes stable after a certain period of time by controlling the power of the heater 4. Around the time when the heating block 2 reaches the set temperature and the heater 4 starts on/off operation, the drain valve 20 is opened and the heat medium in the liquid/air tank 14 is drained.

After the heat medium is removed, the heating block 2 has its own temperature pulsating around the set temperature because the energization of the heater 4 is controlled on and off based on the signal from the temperature sensor 6. However, since the differential refractometer 10 is not in direct contact with the heating block 2 and the heat insulating legs 12 are interposed between the two, the temperature pulsations of the heating block 2 are caused by the differential refractometer 1.
The temperature stability of the differential refractometer 10 is better than that of the heating block 2 itself.

Further, thermal disturbances are mostly blocked by the heat insulating material 8, but even if the temperature of the heating block 2 fluctuates due to the influence of the thermal disturbances, the fluctuations are suppressed by the differential refractometer 1.
It doesn't reach 0.

(Effects of the Invention) In the constant temperature bath of the present invention, a liquid with good thermal conductivity is filled between the detector such as a differential refractometer and the inner surface of the heating block from the start of heating to the set temperature.
The time required for a detector such as a differential refractometer to reach the set temperature is not increased. After the set temperature is reached, heat transfer from the heating block to the detector such as a differential refractometer occurs through an air layer with poor thermal conductivity, so thermal effects such as changes in outside temperature Noise caused by disturbances and heating block pulsations can be suppressed to an extremely low level.

[Brief explanation of the drawing]

The figure is a sectional view showing one embodiment. 2...Heating block, 4...Heater, 6...Temperature sensor, 8...Insulating material, 10...Differential refractometer,
14...Liquid/air tank, 16...Liquid inlet, 18...
...Liquid drain port, 20...Drain valve.

Claims (1)

[Scope of utility model registration request] Equipped with a heater and a temperature sensor, the temperature is controlled at a constant temperature, and the interior is hollow and forms a liquid/air tank, and the outside is surrounded by a heat insulating material to support the heating block and the detector housed within this heating block. A constant temperature bath comprising: a heat insulating member provided between the heating block and the inner surface of the heating block; and means for injecting and discharging a liquid with good thermal conductivity into a liquid/air tank in the heating block.