1 Scope
This standard is applicable to the nitrogen, produced by liquid nitrogen generator, pressure swing nitrogen generator, membrane separation nitrogen generator and special small nitrogen generator, for food additives.
2 Molecular Formula and Relative Molecular Mass
2.1 Molecular Formula
N2
2.2 Relative Molecular Mass
28.01 (as per IUPAC 2007 standard atomic weights)
3 Specification
3.1 Sensory Requirements
Sensory requirements shall be comply with those specified in Table 1.
Table 1 Sense Requirements
Item Requirement Test method
Colour Colourless Connect the relief outlet of gas cylinder with a transparent and colourless hose, open and close the valve in a short time, and observe the colour and state of the hose in natural light
State Gaseous
3.2 Physical and Chemical Indexes
Physical and chemical indexes shall be comply with those specified in Table 2.
Table 2 Physical and Chemical Indexes
Item Index Test method
Nitrogen (N2) content, φ/% ≥ 99.9 Annex A, A.3
Oxygen (O2), φ/% ≤ 0.1 Annex A, A.4
Carbon dioxide (CO2), φ/% ≤ 0.003 GB/T 8984.1
Carbon monoxide (CO), φ/% ≤ 0.001 GB/T 8984.1
Moisture (24000mL of gas), φ/% ≤ 0.005 GB/T 5832.2
Annex A
Test Method
A.1 Warning
The test methods specified in this standard are involved with the use of high-pressure gas cylinders, and proper safety and protection measures shall be taken.
A.2 Identification Test
Carefully insert a live batten into the test tube of test gas, the flame failure.
A.3 Determination of Nitrogen (N2) Content
The volume fraction of Nitrogen (N2) content φ, can be calculated by using Formula (A.1):
φ =100% - φ1 ………………………………(A.1)
Where
φ1 — The volume fraction of oxygen determined in A.4.
A.4 Determination of Oxygen (O2) Content
A.4.1 Electrochemical method
A.4.1.1 Method summary
Place the test sample, in a proper mode, into the electrochemical reaction vessel, determine and calculate the oxygen content by direct or comparative measurement.
A.4.1.2 Instruments and apparatus
Trace oxygen analyzer: in accordance with GB/T 6285.
A.4.1.3 Analytical procedure
Carry out the determination in accordance with the relevant requirements of GB/T 6285, specific operation as specified in instrument instruction.
A.4.2 Zirconia detector (gas chromatography)
A.4.2.1 Method summary
Zirconia solid state battery served as the detector of gas chromatography. After the tested oxygen component in the sample separated from chromatographic column, inject it into detector; when corresponding chromatogram peak signal is generated, carry out the quantative determination by external standard method.
1 Scope
2 Molecular Formula and Relative Molecular Mass
3 Specification
Annex A Test Method
