CR 14539:2002
(Main)Straight ammonium nitrate fertilizers - Comparative study on the determination of porosity (oil retention)
Straight ammonium nitrate fertilizers - Comparative study on the determination of porosity (oil retention)
Preparation of a European Standard test method for the determination of fuel-oil retention of straight ammonium nitrate fertilizers having a content of ammonium nitrate of more than 80u before or after thermal pre-treatment.
Reine Ammoniumnitratdünger - Bestimmung der Porosität (Ölretention)
Engrais simples à base de nitrate d'ammonium - Etude comparative de méthodes de détermination de la porosité (rétention fuel)
Čista amonnitratna gnojila – Primerjalna študija o določevanju poroznosti (zadrževanje olja)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2003
ýLVWDDPRQQLWUDWQDJQRMLOD±3ULPHUMDOQDãWXGLMDRGRORþHYDQMXSRUR]QRVWL
]DGUåHYDQMHROMD
Straight ammonium nitrate fertilizers - Comparative study on the determination of
porosity (oil retention)
Reine Ammoniumnitratdünger - Bestimmung der Porosität (Ölretention)
Engrais simples a base de nitrate d'ammonium - Etude comparative de méthodes de
détermination de la porosité (rétention fuel)
Ta slovenski standard je istoveten z: CR 14539:2002
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN REPORT
CR 14539
RAPPORT CEN
CEN BERICHT
August 2002
ICS
English version
Straight ammonium nitrate fertilizers - Comparative study on the
determination of porosity (oil retention)
Engrais simples à base de nitrate d'ammonium - Etude
comparative de méthodes de détermination de la porosité
(rétention fuel)
This CEN Report was approved by CEN on 13 April 2002. It has been drawn up by the Technical Committee CEN/TC 260.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. CR 14539:2002 E
worldwide for CEN national Members.
Contents
Foreword.3
1 Scope .4
2 Test procedure .4
3 Results and statistical interpretation.5
4 Conclusions.6
Annex A (informative) Characteristics of and limits for straight ammonium nitrate fertilizers of high
nitrogen content as given in EC Directive 80/876/EEC .7
Annex B (informative) Determination of oil retention — EC method as given in EC Directive 87/94/EEC.8
Annex C (informative) Centrifuge method – Non-standardized alternative method .11
Annex D (informative) Roller drum method – Non-standardized alternative method .14
Bibliography .17
Foreword
This document (CR 14539:2002) has been prepared by Technical Committee CEN/TC 260, "Fertilizers and liming
materials", the secretariat of which is held by DIN.
It is published for information only and does not have the status of a European Standard.
The annexes A to D are informative.
Introduction
Straight ammonium nitrate fertilizers of high nitrogen content (> 28 %), following Directive 80/876/EEC [1] and
Directive 87/94/EEC [2], are subject to the particular regulatory requirement of a maximum porosity limit of 4 %.
The currently used official EC method is demanding with respect to time and skilled laboratory manpower.
Therefore CEN/TC 260 agreed to launch a new Work Item, in order to compare non-standardized alternative
methods for measuring porosity with the official one, through ring testing.
Parallelly, oil retention can also be determined by ISO 5313.
1 Scope
This CEN report gives the results of inter-laboratory testing to compare the accuracy and convenience of the official
EC method for porosity measurement (given as Annex B) with two non-standardized alternative methods (given as
Annexes C and D) already used in some participating laboratories.
Three products, with a porosity between 1 % and 7 %, have been used in the inter-laboratory trials.
2 Test procedure
2.1 Methods for measuring porosity
All the methods tested for measurement of ammonium nitrate porosity are based on immersion of the test sample
in gas oil, removing the excess of oil, and finally determining the absorbed amount of oil through weighing. The
methods differ in the way of removing the excess oil.
Table 1 — Methods for measuring porosity
Method Removal of oil Protocol
a
Hand-rubbing between sheets of filter paper see Annex B
Method 1 : EC Method [2]
Method 2 : Centrifuge method Draining and centrifuging see Annex C
Method 3 : Roller drum method Draining and roller drum with filter thimble see Annex D
a
This method is based on ISO 5313, with some minor but significant differences.
WARNING — Appropriate safety rules and procedures should be followed while handling samples and
residues of Ammonium nitrate impregnated with gas oil.
2.2 Products
2.2.1 Test samples: straight ammonium nitrate
Three different ammonium nitrate samples have been provided to all the participants. Two samples were fertilizer
ammonium nitrates of the 33,5 % N type, the third was a special ammonium nitrate, with a higher porosity well over
4 %.
2.2.2 Gas oils
All gas oils used in the ring test conformed to the requirements of Directive 87/94/EEC, Annex II [2]. In order to
improve the accuracy of the ring test, one specific gas oil, distributed centrally in this ring test, has been used as a
reference by all participants, parallel to oils from local origin.
2.3 Ring test procedure
This ring test has been performed by 17 participating laboratories, private ones as well as official ones. Three
ammonium nitrate samples have been tested by three different methods, using a reference gas oil, and oils of local
origin.
In order to avoid the influence of thermal cycling under different circumstances, test samples were prepared
centrally without further thermal cycling by the participating laboratories.
The participating laboratories were requested to perform at least two independent replicates of each sample,
according to each method.
Test results, observations and remarks have been reported on the appropriate sheets.
3 Results and statistical interpretation
3.1 General
Statistical calculations have been run on all the results, according to ISO 5725-2 and ISO 3534-1.
Repeatability and reproducibility have been evaluated for each sample coupled with each method. Evaluations of
the mean result have been carried out through variance analysis.
3.2 Mean value
Mean values for a given method have been evaluated, incorporating the influence of different gas oils and the intra-
laboratory variance.
See table 2.
Table 2 — Mean values
Method Sample number
according
to table 1
12 3
Method 1 2,20 6,22 1,42
Method 2 2,22 6,10 1,51
Method 3 1,89 6,28 1,42
3.3 Repeatability
Table 3 gives the general evaluation of standard deviation with respect to repeatability for each couple
method/sample after checking the equality of variances using Bartlett’s test.
Table 3 — Repeatability
Method Sample number
according
to table 1
12 3
Method 1 0,17 0,20 0,07
Method 2 0,12 0,15 0,06
Method 3 0,10 0,17 0,05
3.4 Reproducibility
Table 4 gives the general evaluation of standard deviation with respect to reproducibility for each couple
method/sample after checking the equality of variances using Bartlett’s test.
Table 4 — Reproducibility
Method Sample number
according
to table 1
12 3
Method 1 0,64 0,73 0,14
Method 2 0,75 0,64 0,28
Method 3 0,47 0,66 0,11
3.5 Interpretation of the results
When the typology of mean results is examined, the statistical proof of the existence of two groups corresponding
to the gas oil type can only be obtained in the case of the couple sample 1/method 1.
The comparison of the mean values obtained by the three methods in all cases, studied by variance analysis of
intra-laboratory means for each test shows that the methods are equivalent.
4 Conclusions
Based upon the above mentioned statistical tests, no significant difference between the methods can be found;
hence the accuracy of the different methods is equivalent.
From a practical point of view, the tested non-standardized alternative methods are more user-friendly and more
convenient than the official EC method.
It could not be shown that there is a statistical difference between results obtained with the different gas oils
conforming to the requirements of Directive 87/94/EEC, Annex II [2].
Annex A
(informative)
Characteristics of and limits for straight ammonium nitrate fertilizers of high
nitrogen content as given in EC Directive 80/876/EEC
A.1 Porosity (oil retention)
The oil retention of the fertilizer, which must first have undergone two thermal cycles of a temperature ranging from
25°C to 50°C, must not exceed 4 % by mass.
A.2 Combustible ingredients
The mass fraction of combustible material in per cent measured as carbon must not exceed 0,2 % for fertilizers
having a nitrogen content of at least 31,5 % (mass fraction) and must not exceed 0,4 % for fertilizers having a
nitrogen content of at least 28 % but less than 31,5 % (mass fraction).
A.3 pH
A solution of 10 g of fertilizer in 100 ml of water must have a pH value of at least 4,5.
A.4 Particle size analysis
Not more than a mass fraction of 5 % of the fertilizer must pass through a 1-mm mesh sieve and not more than a
mass fraction of 3 % must pass through a 0,5-mm mesh sieve.
A.5 Chlorine
The maximum chlorine content is set at 0,02 % (mass fraction).
A.6 Heavy metals
Heavy metals should not be added deliberately, and any traces which are incidental to the production process
should not exceed the limit fixed by the Committee.
The mass fraction of copper shall not be higher than 10 mg/kg.
No limits are specified for other heavy metals.
Annex B
(informative)
Determination of oil retention — EC method as given in EC Directive
87/94/EEC
B.1 General
This annex specifies the procedure for the determination of oil retention of straight ammonium nitrate fertilizers of
high nitrogen content.
The method is applicable to both prilled and granular fertilizers which do not contain oil-soluble materials.
B.2 Terms and definitions
For the purposes of this annex, the following term and definition apply.
B.2.1
oil retention of a fertilizer
the quantity of oil retained by the fertilizer determined under the operating conditions specified.
NOTE The oil retention is expressed as percentage by mass.
B.3 Principle
Total immersion of the test portion in gas oil for a specified period, followed by the draining away of surplus oil
under specified conditions. Measurement of the increase in mass of the test portion.
B.4 Reagents
Gas oil, with:
a maximum viscosity of 5 mPa s at 40°C;
a density of 0,8 g/ml to 0,85 g/ml at 20°C;
a sulphur content of £ 1,0 % (mass fraction);
an ash content of £ 0,1 % (mass fraction).
B.5 Apparatus
Ordinary laboratory apparatus, and in particular:
B.5.1 Balance, capable of weighing to the nearest 0,01 g
B.5.2 Beakers, of capacity 500 ml
B.5.3 Funnel, of plastic materials, preferably with a cylindrical wall at the upper end, diameter approximately
200 mm
B.5.4 Test sieve, nominal aperture size 0,5 mm, fitting into the funnel (B.5.3)
NOTE The size of the funnel and sieve is such as to ensure that only a few granules lie one above another and the oil is
able to drain easily.
B.5.5 Filter paper, rapid filtering grade, creped, soft, mass 150 g/m
B.5.6 Absorbent tissue (laboratory grade)
B.6 Procedure
B.6.1 Two individual determinations are carried out in quick succession on separate portions of the same test
sample.
B.6.2 Remove particles smaller than 0,5 mm using the test sieve (B.5.4). Weigh to the nearest 0,01 g
approximately 50 g of the sample into the beaker (B.5.2). Add sufficient gas oil (B.4) to cover the prills completely
and stir carefully to ensure that the surfaces of all the prills are fully wetted. Cover the beaker (B.5.2) with a watch
glass and leave to stand for 1 h at (25 – 2)°C.
B.6.3 Filter the entire contents of the beaker through the funnel (B.5.3) containing the test sieve (B.5.4). Allow the
portion retained by the test sieve to remain there for 1 h so that most of the excess oil can drain away.
B.6.4 Lay two sheets of filter paper (B.5.5) (about 500 mm · 500 mm) on top of each other on a smooth surface;
fold the four edges of both filter papers upwards to a width of about 40 mm to prevent the prills from rolling away.
Place two layers of absorbent tissue (B.5.6) in the centre of the filter papers. Pour the entire contents of the sieve
(B.5.4) over the absorbent tissues and spread the prills evenly with a soft, flat brush. After 2 min lift one side of the
tissues to transfer the prills to the filter papers beneath and spread them evenly over these with the brush. Lay
another sheet of filter paper (B.5.5), similarly with its edges turned upward, on the sample and roll the prills
between the filter papers with circular movements while exerting a little pressure. Pause after every eight circular
movements to lift the opposite edges of the filter papers and return to the centre the prills that have rolled to the
periphery. Keep to the following procedure: make four complete circular movements, first clockwise and then
anticlockwise. Then roll the prills back to the center as described above. This procedure to be carried out three
times (24 circular movements, edges lifted twice). Carefully insert a new sheet of filter paper (B.5.5) between the
bottom sheet and the one above it and allow the prills
...
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