JPS63144232A - Producing device for standard gas of nitrogen dioxide - Google Patents

Abstract

PURPOSE:To accurately measure the concentration of standard gas to be supplied at the time of use by providing a branch pipe to a duct which supplies standard gas containing nitrogen dioxide, guiding part of it to a quantitative device and a integrating volume flowmeter connected thereto, and measuring the total amount of the nitrogen dioxide and the total volume of the standard gas. CONSTITUTION:A cock 2 is opened to supply the nitrogen dioxide which has constant concentration to the duct from a standard gas supply device 1. The standard gas passes through the branch pipe 4 and is controlled by a cock 2 to a proper flow rate and guided to the nitrogen dioxide quantitative device 5, and the integrating volume flowmeter 6 measures the total amount of the passing gas. The gas passing through the duct 3, on the other hand, is guided to a measuring instrument 7 to be tested. The concentration of the nitrogen dioxide in the standard gas supplied to the measuring instrument 7 is accurately found from the amount of the nitrogen dioxide accurately determined by the quantitative device 5 and the flow rate accurately measured by the flowmeter 6.

Description

DETAILED DESCRIPTION OF THE INVENTION At present, air pollution caused by nitrogen dioxide has become one of the most important pollution problems, and countermeasures are strongly required. From the standpoint of protecting the lives and health of its citizens, the government must accurately understand the situation of pollution and take countermeasures. As a precondition for this, it is necessary to accurately grasp the actual state of pollution, and the measuring instruments used to measure environmental pollution must be reliable and well-managed. According to the Measurement Act, measuring instruments used for commercial transactions and for proving authenticity must be certified by the government. Measuring instruments used for environmental measurements belong to the latter category, and should originally be certified by the government, and a report by the Metrology Administration Council has pointed out that a system for implementing this certification should be in place, but this has not been done to date. This has not yet been realized due to technical difficulties.

The reason for the technical difficulty is that standard gases are currently required by law to be supplied in cylinders, and nitrogen dioxide is chemically active and it is difficult in principle to guarantee concentration stability if it is packed in cylinders. By being.

In order to solve this difficulty, the inventor conducted various studies and arrived at the present invention.
The total amount of nitrogen dioxide and the total volume of the standard gas are measured by a quantitative device that utilizes a stoichiometric reaction with nitrogen dioxide and an integrated volume flow meter connected to it, and the concentration of the standard gas to be supplied is determined at the time of use. This invention relates to a nitrogen dioxide standard gas generator that is characterized by accurate determination.

The inventive device will be further explained with reference to the drawings.

Reference numeral 1 designates a standard gas supply device, 2 a conch, 3 a standard gas conduit, 4 a branch pipe, 5 a nitrogen dioxide quantitative device, 6 an integrated volumetric gas flowmeter, and 7 a measuring instrument used for testing.

The operation of the device of the present invention will be explained with reference to the drawings.

1 may be a standard gas packed in a cylinder with a standard gas supply device and zero gas for diluted gas using a diluted gas supply device, or a bag filled with nitrogen dioxide standard gas adjusted to an arbitrary concentration as needed. An extrusion device is installed accordingly. Hook 2 is opened and nitrogen dioxide at a constant concentration is allowed to flow into conduit 3. One side of this standard gas passes through a branch pipe 4, is adjusted to an appropriate flow rate by a cock 2', and is led to a nitrogen dioxide metering device 5, and the total amount of gas that has passed is measured by an integrated volumetric flow meter 6''C''. Three conduits pass through or are led to a measuring device 7 to be calibrated. The concentration of nitrogen dioxide in the standard gas supplied to the measuring device can be accurately determined from the amount of nitrogen dioxide accurately quantified in step 5 and the flow rate value accurately measured by the integrating volumetric flow meter 6.

A method for stoichiometrically reacting and quantifying nitrogen dioxide is to measure the iodine produced by reacting with heavy metal iodides, etc., and the iodine trace specific method is used to quantify 108 mol of 108 mol.
Can be quantified down to %. By increasing the flow rate, the 1% accuracy required for the primary standard gas can be determined with sufficient accuracy.

It is also inexpensive because it does not require the use of expensive rare equipment.
The practical value is extremely large.

[Brief explanation of the drawing]

The figure is a bronc diagram showing an example of the device of the present invention.

Claims (1)

[Claims] A branch pipe is installed in the conduit that supplies the standard gas containing nitrogen dioxide, and a part of it is guided to a quantitative device that utilizes a stoichiometric reaction with nitrogen dioxide and an integral volumetric flowmeter connected in series to it. A nitrogen dioxide standard gas generator characterized by measuring the total amount of nitrogen and the total volume of standard gas and accurately determining the concentration of the standard gas to be supplied during use.