JPH0525703Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a saturation tank of a constant humidity gas generator that generates gas at a constant humidity.

(Prior Art) In order to calibrate humidity sensing elements and test the humidity characteristics of various materials and parts, devices that generate gas whose humidity is accurately determined are often used. Some of these devices use the split flow method, two-temperature method, two-point pressure method, etc. (JIS humidity measurement method, Z8806). Both devices use a saturated tank that generates gas at a constant water vapor pressure. This takes advantage of the fact that water at a certain temperature exhibits a certain water vapor pressure. Therefore,
In order to generate gas with accurate humidity, the saturation tank is usually placed in a constant temperature bath, and its temperature is precisely controlled.

As described in Japanese Patent Application Laid-open No. 63-123109, the inventor of the present invention has developed a "constant-humidity gas system" that can correctly generate water vapor pressure corresponding to the temperature of a saturation chamber without using a constant-temperature chamber. A saturation tank for generators was proposed.

Figure 2 shows the outline. The gas that has passed through the gas inlet 2 provided at the bottom of the saturation tank body 1 is
Fine bubbles pass through the water 4 from the large number of small holes in the filter 3, become saturated gas, and reach the upper space 5 of the saturation tank body 1. The temperature of the water 4 in the saturation tank is appropriately set to a desired temperature by a heating (cooling) coil 7. In the case of this invention, since the saturation tank main body 1 is not placed in a constant temperature tank, it must be assumed that a temperature difference will always occur between the water 4 and the upper space 5 due to the influence of the air temperature outside the saturation tank. When the temperature of the upper space 5 or the wall of the upper space 5 is lower than the water temperature, the water vapor in the saturated gas is partially condensed there, and the gas is dehumidified. When the temperature of the upper space 5 or the vessel wall of the upper space 5 is high, water droplets brought to the upper part of the saturation tank along with the air bubbles evaporate, and the gas becomes humid. The upper space 5 is insulated (cooled)
It would be possible to keep the water temperature the same as the water temperature in the saturation tank, but this would require extremely technical and sophisticated temperature control. Therefore, it is difficult to judge whether this method is superior or inferior to the conventional method of placing a saturation tank inside a constant temperature tank.

The generated gas is transferred from the upper space 5 of the saturation tank to the gas outlet pipe 8.
through the saturated gas outlet 9 below the saturated gas water surface.
It is now being supplied to the outside world. Therefore, if the temperature of the upper space 5 is set higher than that of the water 4 (precise temperature control is not required), the gas will be humidified in the upper space 5, as described above, but
When passing through the gas outlet pipe 8, the water vapor condenses in a portion below the water surface (equal to the temperature of the water 4). If the length and surface area of the condensation line are appropriate, gas with a saturated vapor pressure corresponding to the water temperature in the saturated tank can be obtained from the saturated gas outlet 9. Water condensed in the gas outlet pipe 8 is discharged to the outside through a water sealing device 10.

As the gas outlet pipe 8, a hydrophobic porous pipe that does not allow water to pass through but allows water vapor to pass therethrough may be used. In this case, the temperature of the upper space 5 may be lower than that of the water 4. Even if the humidity is reduced in the upper space 5,
This is because water vapor is replenished into the gas through the porous wall of the gas outlet pipe 8 up to the water vapor pressure of the temperature of the water 4.

In this way, it is possible to generate a gas with a water vapor pressure determined only by the water temperature in the saturation tank without using a constant temperature tank, so the device can be made compact and economically advantageous. be. Also, because the heat capacity is small, it has become possible to rapidly change the temperature of the saturation tank.

(Problem to be solved by the invention) However, because the above-mentioned saturation tank cannot be frozen due to its structure, it cannot generate gas with a dew point below 0°C (water vapor pressure below 4.5804 mmHg). . When the dew point is 0℃, the water vapor pressure of the gas is
This corresponds to 4.5804mmHg. When dry gas (water vapor pressure 0 mmHg) is mixed with a gas (water vapor pressure 4.5804 mmHg or higher) with a dew point of 0°C or higher, the water vapor pressure of that gas decreases. If the amount of drying gas is selected appropriately, the gas can have a dew point of water vapor of 4.5804 mmHg or less, that is, 0° C. or less. To produce a gas with a low dew point of 0° C. or lower, for example, a branch pipe 11 may be provided as shown by the dotted line in FIG. 2, and dry gas may be mixed with the saturated gas. 100% depending on the proportion of that mixture
Gas with any humidity below RH can be obtained. In this case the temperatures of the drying gas and the saturated gas are generally not the same. If the temperature of the drying gas is lower than that of the saturated gas, condensation may occur in the mixed gas, so it is desirable that the drying and saturated gases have the same temperature.

(Means for Solving the Problems) The present invention provides a means for making dry gas and saturated gas the same temperature without using any special heating or cooling means. The heat exchanger is characterized by being provided with a heat exchanger that passes through the water in the saturation tank main body and whose end in the water is connected to a gas outlet pipe that guides the saturated gas.

(Function) When dry gas is introduced into the heat exchanger, the temperature of this dry gas becomes the same as the water temperature in the saturated tank, and it is possible to generate a gas that is the water temperature of the saturated tank and has a humidity lower than the saturated water vapor pressure. .

(Example) Examples will be described below. FIG. 1 is a schematic diagram of a preferred embodiment of the present invention. (Identical parts have been given the same numbers). In this embodiment, saturated gas is generated using the same mechanism as in FIG. The dry gas passes through a coil-shaped heat exchanger 12 provided in the water in the saturation tank 1, and the temperature of the dry gas becomes the same as the water temperature in the saturation tank 1. The end of the heat exchanger 12 is connected to a saturated gas extraction pipe 13 underwater in the saturation tank 1, where the dry gas and saturated gas are mixed and supplied to the outside of the saturation tank. In this way, a gas with lower humidity than saturated gas (100% RH) can be easily generated.

(Effects of the invention) According to the invention, dry gas can be brought to the same temperature as saturated gas without using any special heating or cooling means. Therefore, it is possible to easily generate a gas having a humidity equal to the temperature of the saturated tank and lower than the saturated water vapor pressure.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a preferred embodiment of the present invention;
The figure is a schematic diagram of the saturation tank on which this invention is based. 1...Saturation tank main body, 2...Gas inlet, 3...
Filter, 4...Water, 5...Upper space, 7...
Heating (cooling) coil, 8... Gas outlet pipe, 10...
... Water sealing device, 11 ... Branch pipe, 12 ... Heat exchanger.

Claims (1)

[Claims for Utility Model Registration] Constant-humidity gas generation in which the saturated gas that has once reached the upper space through the water filled in the saturation tank body is passed through the gas outlet pipe that passes through the water again and then is supplied to the outside. In the saturation tank of the device, a heat exchanger through which dry gas is introduced is provided under water in the saturation tank main body, and an end of the heat exchanger in the water is connected to the gas outlet pipe. Tank.