DRAFT UGANDA STANDARD  
     DUS 2036  
First Edition  
2019 -mm-dd 
  
 
 Reference number  
DUS 2036: 201 9 
© UNBS 2018   
  
Food grade n itrogen — Specification  
 DUS 2036 : 2019  
ii © UNBS 2017  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNB S 2017  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior written 
permission from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 41 7 333 250/1/2  
Fax: +256 414 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 2036:2019  
© UNBS 2017  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................  iv 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Requirements  ................................ ................................ ................................ ................................  1 
4.1 General requirements  ................................ ................................ ................................ ..................  1 
4.2 Specific requirements  ................................ ................................ ................................ ..................  1 
5 Packaging  ................................ ................................ ................................ ................................ ...... 2 
6 Weights and Measures ................................ ................................ ................................ .................  2 
7 Labelling  ................................ ................................ ................................ ................................ ........  2 
8 Sampling  ................................ ................................ ................................ ................................ ....... 2 
Annex  A (normative)  Sampling of nitrogen  ................................ ................................ ...........................  3 
Annex  B  (normative)   Assay: Percentage purity by gas chromatography  ................................ ........  4 
Annex  C  (normative)   Test for oxygen  ................................ ................................ ................................ .. 5 
Annex  D  (normative)   Test for carbon monoxide  ................................ ................................ .................  6 
Bibliography  ................................ ................................ ................................ ................................ ...............  7 
 DUS 2036 : 2019  
iv © UNBS 2017  – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established under Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Sta ndardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried out through T echnical Committees. A Technical Committee 
is established to deliberate on standards in a given field or area and consists of key stakeholders including 
government, academia, consumer groups, private sector and other interested parties.  
Draft Uganda Stand ards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National S tandards Council.  
The committee responsible for this document is UNBS/TC 2 [ Food and Agriculture standards ], Subcommittee 
SC 6, [ Food Additives and contaminants ]. 
  DRAFT UGANDA STANDARD  DUS 2036: 201 9 
 
© UNBS 2017 – All rights  reserved  1 
 Food grade nitrogen  — Specification  
1 Scope  
This Draft Uganda S tandard specifies requirements  and methods of sampling and test for food grade nitrogen .  
2 Normative references  
The following referenced documents are referred to in the text in such a way that some or all their content 
constitutes requirements of this document. For dated references, only the edition cited applies. For undated 
references, the latest edition of the referenced document (including any amendments) applies.  
US 277, General standard for the label ling of food additives when sold as such  
3 Terms and definitions  
For the purposes of this document, the following terms and definitions apply.  
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online  browsing platform: available at http://www.iso.org/obp   
food grade material  
material, made of substances that  are safe and suitable for their intended use and which will not impart any 
toxic substance or undesirable odour or flavour to the product  
4 Requirements  
4.1 General  requirements  
Food grade nitrogen  shall: 
a) be a colourless, odourless  gas or liquid ; and  
b) extinguish any flame in its atmosphere . 
4.2 Specific requirements  
Food grade nitrogen  shall com ply with the specific  requirements given in Table 1  when tested in accordance 
with the test methods  specified therein . 
Table 1 — Specific r equirements for food grade  nitrogen  
S/N Characteristic  Requirement  Test method  
i) Percentage purity, %v/v, min.  99.0 Annex B 
ii) Oxygen, %v/v, max . 1.0 Annex C 
iii) Carbon monoxide, μl/l, max.   10 Annex D DUS 2036: 2019  
2 © UNBS 2017  – All rights reserved  
 5 Packaging  
Food grade nitrogen shall be packaged in  clean, sound , leak-proof  compressed  cylinders  made of food grade 
materials .  
6 Weights and Measures  
The weight of the package s shall comply with the  Weights and Measures Regulations of Uganda . 
7 Labelling  
In addition to the requirements of US 277, the product shall be l egibly and indelibly labelled with the following 
information:  
a) name of the product as: “Food grade Nitrogen”  
b) Lot/batch identification  
c) best before date;  
d) Name and physical address of the manufacturer/distributor;   
e) instructions of use ;  
f) storage instructions; and 
g) precaution s for handling and storage .  
8 Sampling  
Representative samples of the product shall be drawn in accordance with the procedure elaborated in Annex 
A. DUS 2036: 2019  
© UNBS 2017  – All rights reserved  3 
 Annex  A 
(normative)  
 
Sampling of nitrogen  
A.1 Scale of sampling  
A.1.1 Lot — In any consignment, all cylinders packaged during one production cycle shall constitute a lot.  
A.1.2  The number ( n) of cylinders to be selected from each lot shall  depend on the lot size ( N) and shall be 
obtained as indicated in Table A-1. 
Table A -1 — Scale  of sampling for nitrogen  
Lot size  
N Sample  
n 
Up to 50  5 
51 – 100 8 
101 – 150 15 
151 – 300 20 
301 and above  25 
 
A.1.3  The cylinders shall be selected at random.  
A.2 Test samples  
One sample of gas shall be drawn from each cylinder selected as in Table A-1 above and shall be the individual 
test sample from each cylinder.  
A.3 Number of tests  
All the individual test samples  from each lot prepared as in A. 2 shall be tested separately for all the requirements 
given in Table 1.  
A.4 Criterion for conform ity 
B-4.1 A lot shall be declared as conform ing to the requirements of this standard when all the individual test 
results satisfy the relevant requirements  given in Table 1.  
 DUS 2036: 2019  
4 © UNBS 2017  – All rights reserved  
 Annex  B  
(normative )  
 
Assay: P ercentage purity  by gas chromatography   
B.1 Apparatus  
B.1.1 Gas chromatography conditions  
Column  
- Mater ial: stainless steel  
- Length: 2 m   
- Internal diameter: 2 mm  
- Packing material: appropriate molecular sieve capable of absorbing molecules with diameters up to 0.5 
nm. 
Carrier  
- Gas: helium (not less than 99.995 % (v/v) of He)  
- Flow: 40 ml/min  
- Detector: thermal conductivity detector  
- Injector: loop injector  
- Column temperature: 50 ºC 
- Detector temperature: 130 ºC 
- Reference gas (a): ambient air  
- Reference gas (b): Nit rogen (not less than 99.999 % (v/v) of N 2, less than 1 ppm  CO, less than 5 ppm 
O2) 
B.1.2 Procedure  
Inject reference gas (a). Adjust the injected volumes and operating conditions so that the height of the peak due 
to nitrogen in the chromatogram is at least 35 % of full scale of the recorder.  
The assay is not valid unless the chromatograms obtained show  a clear separation of oxygen and nitrogen.  
Inject the gas to be examined and the reference gas (b). In the chromatogram obtained with the gas to be 
examined, the area of the principal peak is at least 99.0 % of the area of the principal peak in the chrom atogram 
obtained with reference gas (b) . DUS 2036: 2019  
© UNBS 2017  – All rights reserved  5 
 Annex  C  
(normative)  
 
Test for oxygen  
C.1 Apparatus  
C.1.1  An Oxygen analyser with an electrochemical cell and a detector scale ranging from 0 μl/l to 100 μl/l.  
C.1.2 Pressure regulator   
C.1.3  Airtight metal tubes  
NOTE: The analys er shall be  calibrated according to the manufacturer ’s instructions.  
C.2 Reagents  
Aqueous potassium hydroxide solution   
C.3 Procedure  
The sample of the gas to be examined is passed through a detection cell containing  an aqueous solution of 
potassium hydroxide. Oxygen in the sample gas produces variation in the electrical signal recorded at the outlet 
of the cell that is proportional to the oxygen content.  
Pass the gas through the ana lyser using a suitable pressure regulator and airtight metal tubes and operating at 
the prescribed flow -rates until constant readings are obtained.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 DUS 2036: 2019  
6 © UNBS 2017  – All rights reserved  
 Annex  D  
(normative)  
 
Test for carbon monox ide 
D.1 Apparatus  
D.1.1  Carbon monoxide detector tube  
D.2 Procedure  
Pass 1050 ± 50 ml of the gas sample through a carbon monoxide detector tube at the rate specified for the 
tube. The indicator change corresponds to not more than 10 μl/l.  
 DUS 2036: 2019  
© UNBS 2017  – All rights reserved  7 
 Bibliography  
[1] IS: 1747 –1972 , specification for nitrogen  (Reaffirmed in 2010)  
[2] Nitrogen, JECFA Specification (1999)  DUS 2036 : 2019  
© UNBS 2017 – All rights  reserved  9 
 Certification marking  
Products that conform to Uganda  standards may be marked with Uganda National Bureau of Standards (UNBS) 
Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only  by those licensed under the certification mark scheme operated by the 
Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The presence of 
this mark on a product or in relation to a product is an assurance that the goo ds comply with the requirements 
of that standard under a system of supervision, control and testing in accordance with the certification mark 
scheme of the Uganda National Bureau of Standards. UNBS marked products are continually checked by UNBS 
for confor mity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda National 
Bureau of Standards.  
 
 
DUS 2036: 2019    
 
ICS 67.220.20  
Price based on nn pages  
© UNBS 2017  – All rights reserved