JPH04258743A - Density measuring method - Google Patents

Abstract

PURPOSE:To measure the density of a irregular-shaped material. CONSTITUTION:A sample S is stored in a sample container 3 with a known inner capacity, measurement gas is filled, the measurement gas in the sample container 3 is discharged into a gas detector 7 by carrier gas, and the signal from the gas detector 7 is integrated and converted into the volume of the vacant space of the sample container 3. The quotient of the mass of the sample S divided by the difference between the volume of the sample container 3 and the vacant space of the sample container 3 is obtained. The measurement gas filled in the sample container 3 containing the sample S is discharged into the gas detector 7 by the carrier gas, the integration value of the output is obtained, thus the volume of the vacant space of the sample container 3 can be known. Even if the sample S, sample container 3 and gas do not attain the temperature equilibrium state in the process, the quantity of the gas to be measured is not changed, and the volume of the vacant space of the sample container 3, i.e., the volume of the sample S, can be correctly measured without waiting for the temperature equilibrium.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring the density of an irregularly shaped object whose volume is difficult to measure.

0002

2. Description of the Related Art When measuring the density of an object whose volume is difficult to determine, the volume is usually measured at a constant volume V1 as shown in FIG.
After accommodating the object to be measured Q in the sample chamber A having a constant pressure P1, the sample chamber A is communicated with the expansion chamber B having a constant volume V2 by opening the valve C. Measure the pressure P2 at the time. These pressures P1, P2, V1, V2
This is done by finding the volume Vs of the object to be measured Q as V1-V2/{(P1/P2)-1} based on Boyle-Charles' law, and then measuring its mass and calculating the density. There is.

0003

[Problem to be solved by the invention] However, since the pressure of the gas, which is greatly influenced by temperature, is used as a measurement parameter, it is difficult for the temperature of the object to be measured and the temperature of the measurement gas to reach an equilibrium state. Therefore, it is necessary to wait for 10
There is a problem in that the measurement takes a long time, ranging from 20 minutes to 20 minutes.

The present invention has been made in view of these problems, and its purpose is to propose a density measuring method that can measure the density of irregularly shaped substances in a short time.

[0005]

[Means for Solving the Problems] In order to solve such problems, the present invention includes a step of accommodating a sample in a sample container with a known internal volume and injecting a measurement gas into the sample container, and a step of filling the sample container with a carrier gas. a step of discharging the measurement gas in the sample container to the gas detection means, integrating the signal from the gas detection means and converting it into the volume of the empty space of the sample container, the mass of the sample, the volume of the sample container and the sample container; The method includes a step of calculating the quotient of the difference between the volume of the empty space and the volume of the empty space.

[0006]

[Operation] Measuring the concentration of the measurement gas filled in the sample container containing the sample while expelling it to the gas detection means using a carrier gas, and determining the integral value of this to know the volume of the empty space in the sample container. Can be done. Even if the sample, sample container, and gas have not reached a temperature equilibrium state during this process, the amount of measurement gas will not change, so the volume of the empty space in the sample container can be calculated without waiting for temperature equilibrium.
In other words, the volume of the sample can be measured accurately.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be explained below based on illustrated embodiments. FIG. 1 shows an embodiment of the device used in the present invention, in which reference numeral 1 is a switching valve, which has a first flow path indicated by a solid line in the figure and a second flow path indicated by a dotted line in the figure. The first flow path is configured to be switchable between the
A flow path for injecting a measurement gas, for example, an easily detectable gas such as helium, into the sample container 3 from the measurement gas inlet 2, and a resistance tube for the carrier gas flowing from the carrier gas source 4 through the volume verification section 5. 6 to form a flow path leading to a gas detector 7, in this embodiment a thermal conductivity type gas detector.

A second flow path indicated by a dotted line in the figure forms a flow path from the carrier gas source 4 to the gas detector 7 via the sample container 3 and the resistance tube 6.

In this apparatus, when the sample S to be measured is housed in the sample container 3, the switching valve 1 is set to the first flow path (the flow path indicated by the solid line in the figure) and the measurement gas is injected. , a measurement gas is filled in the space excluding the sample. Next, when the switching valve 1 is switched to the second flow path, the carrier gas from the carrier gas source 4 passes through the reference cell side of the gas detector 7, flows into the sample container 3 via the switching valve 1, and the carrier gas flows into the sample container 3 through the switching valve 1. The measurement gas contained in the container 3 is discharged through the resistance tube 6 to the detection cell side of the gas detector 7. The gas detector 7 outputs a signal (FIG. 2) that is proportional to the concentration of the measurement gas contained in the carrier gas, so by integrating this signal using the integrating circuit 8, the volume Vs of the space in the sample container can be calculated. You can know. Needless to say, the integral value is proportional to the amount of the injected measurement gas, so even if the temperature of the measurement gas changes during measurement, the integral value will not be affected.

Furthermore, since the internal volume V0 of the sample container 3 is known, the volume V0-Vs of the sample contained in the sample container 3 can be determined by determining the difference V0-Vs between the two. Calculate the ratio of the sample volume V0−Vs obtained in this way to the sample mass W obtained in advance by calculating W/
The density can be determined by (V0-Vs).

It is clear that if the internal volume of the sample container is unknown, the internal volume may be measured using the same method as described above without containing the sample.

0012

[Effects of the Invention] As explained above, in the present invention,
A process of storing a sample in a sample container with a known internal volume and injecting a measurement gas, and discharging the measurement gas in the sample container to the gas detection means using a carrier gas and integrating the signal from the gas detection means. The method includes a step of converting the volume of the empty space in the sample container, and a step of calculating the quotient of the difference between the mass of the sample, the volume of the sample container, and the volume of the empty space of the sample container. The volume of the sample can be determined without waiting for temperature equilibrium between the measurement gases, and the density of the sample can be measured in an extremely short time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of an apparatus used for density measurement according to the present invention.

FIG. 2 is a diagram showing signals from a gas detector in the same device.

FIG. 3 is an explanatory diagram showing a conventional method for measuring the volume of an irregularly shaped object.

[Explanation of symbols]

1 Switching valve 2 Gas inlet for measurement 3 Sample container 4 Carrier gas source 7 Gas detector

Claims (1)

[Claims] 1. A step of accommodating a sample in a sample container with a known internal volume and injecting a measurement gas into the sample container, and discharging the measurement gas in the sample container to a gas detection means using a carrier gas, from the gas detection means. A density measurement method comprising the steps of integrating the signal and converting it to the volume of the empty space in the sample container, and calculating the quotient of the difference between the mass of the sample and the volume of the sample container and the volume of the empty space in the sample container. .