KENYA STANDARD
DKS 2200-1:2009
Nitrogen —Specification
Part 1:
High Purity Nitrogen
PUBLIC REVIEW DRAFT
©KEBS 2009
MAY 2009
First Edition 2009
DKS 2200-1:2009
TECHNICAL COMMITTEE REPRESENTATION
The following organizations were represented on the Technical Committee:
Consumer Information Network
BOC Kenya Ltd
Noble Gases International Ltd
Chemigas Ltd
Synergy Gases (K) Ltd
Carbacid (CO2) Ltd
Government Chemist’s Department
Kenya Industrial Research and Development Institute (KIRDI)
Kenyatta University, Chemistry Dept
Kenya Science Teachers College
Ministry of Roads and Public Works – Materials Branch
Kenya Industrial Estates
Kenyatta National Hospital
Ministry of Medical Services
Kenya Bureau of Standards — Secretariat
REVISION OF KENYA STANDARDS
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions for
improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are
welcome.
© Kenya Bureau of Standards, 2009
Copyright. Users are reminded that by virtue of section 6 of the Copyright Act, Cap. 130 of the Laws of Kenya, copyright subsists in all
Kenya Standards and except as provided under section 7 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be
reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the Managing
Director.
KENYA STANDARD
DKS 2200-1:2009
Nitrogen —Specification
Part 1:
High Purity Nitrogen
KENYA BUREAU OF STANDARDS (KEBS)
Head Office: P.O. Box 54974, Nairobi-00200, Tel.: (+254 020) 605490, 602350, Fax: (+254 020) 604031
E-Mail: [email protected], Web:http://www.kebs.org
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DKS 2200-1:2009
Foreword
This standard has been prepared by the Technical Committee on Gases under the guidance of the Standards
Projects Committee, and it is in accordance with the procedures of the Kenya Bureau of Standards.
High Purity Nitrogen covered in this standard is intended for specialised use such as analytical use, research
programmes involving work in inert atmospheres, manufacture of oxygen-labile organic chemicals and
pharmaceuticals.
The standard specifies limits on impurities such as oxygen, carbon monoxide, carbon dioxide, oil, total
hydrocarbons and water.
Purity requirements are also covered in this standard.
During the development of this standard, reference was made to the following documents:
BS: 4366:1993 British standard specification for industrial Nitrogen
Cox, J., Halliday, D. and Kilminister, K.(1990), A guide to the establishment and maintenance of pesticide
laboratories in developing countries, Natural Resources Institute bulleting no. 28, iv + 79pp.
Acknowledgement is hereby made for the assistance received from these sources.
©KEBS 2009 — All rights reserved
2
DKS 2200-1:2009
KENYA STANDARD
DKS 2200-1:2009
Nitrogen —Specification
Part 1:
High Purity Nitrogen
1
Scope
This standard prescribes the requirements and test methods for compressed high Purity Nitrogen in the form of
liquid or gas.
2
Normative reference
The following standard contains provisions which, through reference in this text, constitute provisions of this
Kenya Standard. For undated reference, the latest edition of the normative document referred to applies.
KS ISO 7225, Gas cylinders — Precautionary labels
KS 09-532, Specification for standard atmospheric conditions for test purposes
3
Terms and Definitions
For the purposes of this Standard the following terms and definitions shall apply.
3.4 STP
standard atmospheric temperature and pressure as per KS 09-532
4
Requirements
4.1
Purity
When tested in accordance with the method specified in annex A, Nitrogen in gaseous form or gasified liquid
Nitrogen shall have a minimum of 99.998 % v/v nitrogen content.
4.2
Impurities
The product shall be colourless, odourless and shall comply with the impurities limits given table 1.
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DKS 2200-1:2009
Table 1 - Impurity limits for Nitrogen
SL
NO.
1.
Characteristic
Requirement
Test method
Oxygen % v/v, Max
0.0004
Annex B
2.
Carbon monoxide % v/v, max
0.0005
Annex C
3.
Carbon dioxide % v/v, max
0.0001
Annex C
4.
Total hydrocarbons % v/v, max
0.0001
Annex D
5.
Water % v/v , max
0.0005
Annex E
5
Packing and marking
5.1
Packing
The product shall be supplied as compressed gas or liquid at cryogenic temperature, in appropriate steel
cylinders complying with relevant Kenya standards. Valves or taps shall not be lubricated with oil or grease.
5.2
5.2.1
Marking
Cylinder
Each cylinder shall be clearly and indelibly marked with the following information:
a)
The words “Nitrogen, High Purity”;
b)
The name or registered trade mark and address of the manufacturer;
c)
Purity;
d)
The impurities limits in table 1, as applicable;
e)
Batch number and;
f)
Date of filling;
g)
Filling pressure (at STP) for product in gaseous form;
h)
Net Weight of contents in Kg for product in liquid form.
5.2.2
Colour and chemical formula
Each cylinder shall in addition to the markings in 5.2.1, be clearly and indelibly painted with the colour grey in the
body and black and white alternating spaced stenciled shoulders and marked with the chemical formula
corresponding to Nitrogen.
5.2.3
Precautionary labels
Each cylinder shall in addition to the markings in 5.2.1, be clearly and indelibly marked with precautionary labels
as specified in KS ISO 7225.
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DKS 2200-1:2009
Annex A
(Normative)
Method for the determination of Purity of Nitrogen
A.1
Principle
Nitrogen content is determined by determining the total content of specified impurities as per annexes B to E and
reporting the balance as Nitrogen, plus any traces of noble of gases present.
A.2
Procedure
Determine total specified impurities by adding the results obtained in Annexes B to E.
A.3
Calculation
Purity of Nitrogen is calculated as:
P
Where P
T
= 100 –T
= Purity (% v/v)
=Total specified impurities (% v/v)
Report Purity results to three decimal places.
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DKS 2200-1:2009
Annex B
(Normative)
Method for the determination of oxygen content
B.1
Principle
The method uses the principle of electrochemical reduction of any oxygen present in a stream in a detection cell
containing either a gel or aqueous solution of electrolyte where the following reactions take place:
O2 + 2H2O + 4e → 4OH – at the cathode and
2Pb + 4OH - → 2Pb(OH)2 + 4e at the anode, with the complete reaction represented by:
2Pb + O2 + 2H2O → 2Pb(OH)2
In some instances, electrodes other than lead may be used.
B.2
Apparatus
A variety of analytical equipment suppliers provide simple, ready to run portable units for this purpose, which
may be powered either by battery or mains electricity.
Figure B.1 illustrates the configuration of a typical unit designed for this purpose using aqueous electrolyte.
Note 1
such units require flow to produce any pertinent signal output and to assist in calibration an adsorbent oxygen scrubber is included
in the analyzer circuit.
Figure B.2 illustrates the configuration of a typical unit designed for this purpose using gel as an electrolyte.
Note 2
In this instance any flow variation is not crucial to the measurement.
B.3
Calibration
Calibration of these units shall be carried out in accordance with the manufacturer’s instructions using a gas
calibration mixture containing Oxygen. The minimum value indicated is 0.0005 % or less.
B.4
Procedure
After calibrating the instrument, introduce the sample of the product in accordance with the manufacturer’s
instructions. Record the oxygen content that is displayed by the instrument.
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DKS 2200-1:2009
Figure B.1 – Configuration of unit for electrochemical determination of oxygen
using aqueous electrolyte
Figure B.2 – Configuration of unit for electrochemical determination of oxygen
using gel electrolyte
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DKS 2200-1:2009
Annex C
(Normative)
Method for the determination of carbon monoxide and carbon dioxide content
C.1
Principle
The method uses the principle of infra-red absorption by different molecules at specific wavelengths in the infrared spectrum.
C.2
Apparatus
C.2.1
Scanning infra-red spectrometer –Fitted with a gas cell of 10 m minimum optical path length.
C.3
Calibration
Calibration of these units shall be carried out in accordance with the manufacturer’s instructions using a gas
calibration mixture containing Carbon Monoxide and Carbon dioxide. The minimum value indicated is 0.0001 %
or less for Carbon dioxide and 0.0005 % or less for Carbon Monoxide.
C.4
Procedure
After calibrating the instrument, introduce the sample of the product in accordance with the manufacturer’s
instructions and calculate the carbon monoxide and carbon dioxide contents.
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DKS 2200-1:2009
Annex D
(Normative)
Method for the determination of total hydrocarbons content
D.1
Principle
The method uses the principle of ionizing the hydrocarbon molecules that are present in a particular sample in a
flame, and monitoring the change in potential across two electrodes in close proximity to the flame, as illustrated
in figure D.1. The change in potential is proportional to the quantity of hydrocarbons present.
Figure D.1 – Flame ionization detector (schematic)
D.2
Apparatus
D.2.1 Gas chromatograph – Fitted with a flame ionization detector, a gas sampling valve, and a suitable
valve to enable hydrocarbons to be ‘back flushed’ to the detector. Nitrogen carrier gas shall be used.
Note
Many other variables, such as column type, length, carrier flow, detector temperature and oven temperature, may be left open, and
still provide a suitable system for determination of this impurity.
D.3
Calibration
Calibration of these units shall be carried out in accordance with the manufacturer’s instructions using a gas
calibration mixture. The mixture shall, however, contain only methane in a balance of nitrogen, and the result of
the calibration shall be expressed as ‘Total hydrocarbons calibrated as methane’. The minimum value indicated
is 0.0001 % or less.
D.4
Procedure
After calibrating the instrument, introduce the sample of the product in accordance with the manufacturer’s
instructions. Record the output signal on a computing integrator, and calculate the concentration of
hydrocarbons in accordance with the computing integrator manufacturer’s instructions.
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DKS 2200-1:2009
Annex E
(Normative)
Method for the determination of water content
E.1
Principle
The gas is passed through a direct reading hygrometer.
E.2
Apparatus
E.2.1
A direct reading hygrometer – of one of the following types:
a)
b)
c)
d)
cooled mirror dew point;
electrolytic;
capacitance;
piezoelectric.
E.3
Calibration
Ensure that the instrument has a current certificate of calibration demonstrating traceability to a physical
standard held at the KEBS Metrology Laboratory or a recognized international body.
E.4
Procedure
Operate the direct reading hygrometer in accordance with the manufacturer’s instructions. Keep all sample lines
as short as practicable and, together with all ancillary equipment, ensure that they have only
polytetrafluorethylene or stainless product in accordance with the manufacturer’s instructions.
Record the water content that is displayed by the instrument.
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