DRAFT TANZANIA STANDARD  
 
 
 
 
GDC 4 ( 1078 ) DTZS Plastics - Thermoplastic silage films and tubes - Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF STANDARDS  
 
 
 
© TBS 202 2 — all rights reserved                                   1st Edition  
 
 EXECUTIVE SUMMARY OF  GDC 4 (1078) DTZS Plastics - Thermoplastic silage films 
and tubes - Specification  
This draft Tanzania standard specifies requirements, method of sampling and test for 
thermoplastic silage films and tubes for agriculture purposes.  
This draft Tanzania standard is applicable to transparent, black, white or colored 
thermoplastic silage films and tubes.  
This draft standard does not cover silage films obtained by sealing two or more films in 
mach ine direction.  
It is anticipated that this draft Tanzania Standard will be made COMPULSORY i n its 
application.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
  
 
 
 
 
NATIONAL FOREWORDS  
 
0.1 The Tanzania Bureau of Standards is the statutory national standards body for 
Tanzania, established under the Act.No.3 of 1975, amended by Act.No.2 of 2009.  
 
This draft Tanzania Standard has been adopted by Packaging Technical committee, 
under the supervision of the General Techniques Standards Divisional Committee 
(GTDC) and it is in accordance with the procedures of the Bureau.  
 
During preparation of this standard, assistance was drawn from the following document:  
     
        EN 13207 Plastics - Thermoplastic silage films and tubes for use in agriculture.  
 
Acknowledgement is hereby m ade for the assistance derived from this source.  
 
 
0.2 Terminology and conventions  
 
Some terminology and certain conventions are not identical with those used as Tanzania 
Standard; attention is drawn to the following:  
 
The comma has been used as decimal ma rker for metric dimensions. In Tanzania, its 
current practice to use a full point on the baseline as decimal marker.  
 
Whenever the words “International Standard” appear, referring to this draft Tanzania 
Standard, they should read as “Tanzania Standard”.  
 
 
 
 
 
 
  
 1. Scope  
This draft Tanzania standard specifies requirements, method of sampling and test for 
thermoplastic silage films and tubes for agriculture purposes.  
This draft Tanzania standard is applicable to transparent, black, white or colored 
thermoplastic  silage films and tubes.  
This draft standard does not cover silage films obtained by sealing two or more films in 
machine direction.  
2. Normative references  
The following documents are referred to in the text in such a way that some or all of their 
contents constitute 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.  
ISO 527 -3:2018 Plastics — determination of tensile pro perties — part 3: test 
conditions for films and sheets  
ISO 7765 -1 Plastics film and sheeting — determination of impact resistance by the 
free-falling   dart method — part 1: staircase methods  
ISO 15105 -2:2003 Plastics — Film and sheeting — determination of  gas-
transmission rate — part 2: equal -pressure method  
ISO 2528:2017 Sheet materials — determination of water vapour transmission rate 
(WVTR) — gravimetric (dish) method  
3. Terms and definitions  
 
For the purpose of this document, the following terms and definitions shall apply.  
ISO and IEC maintain terminological databases for use in standardization at the following 
addresses:  
            IEC Electropedia: available at http://www.electropedia.org/  
            ISO Online browsing platform: available at htt p://www.iso.org/obp  
3.1  
width  
overall width of the film when laid flat   
 
3.2  
nominal width  
width of the film, as declared by manufacturer or supplier  
  
 3.3  
nominal thickness  
thickness of a film , as declared by manufacturer or supplier  
3.4  
roll length  
 largest dimension of the film corresponding to the length of the unwinded roll  
3.5  
nominal length  
length of the film roll or sheet  as declared by manufacturer or supplier  
 
3.6  
longitudinal (machine)direction  
MD 
direction parallel to the roll length, corresponding to the extrusion direction  
 
3.7  
transverse direction  
TD 
direction to the width (at right angle to the length)  
 
4. Types and use  
 
The silage films in accordance with this standard shall be classified into the following 
types;  
 
4.1.  Type1 -film or tube suitable for food contact with nominal thickness greater 
than or equal to 90 μm. 
 
4.2. Type 2 -film or tube not suitable for food contact with nominal thickness 
greater than or equal to 100 μm. 
 
4.3. Type 3 -film or tube used as lining in combination addition to type 1 and type 
2 with nominal thickness greater than or equal to 35 μm. 
  
 4.4. Type 4 - film or tube having at least one coextruded layer made from a gas 
barrier polym er (e.g. EVOH or polyamide) with nominal thickness greater than or 
equal to 90 μm. 
 
4.5. Type 5 -film or tube having at least one coextruded layer made from a gas 
barrier polymer used as lining in combination to type 1 and type 2 with nominal 
thickness greater t han or equal to 35 μm. 
 
5. Materials  
Silage films in accordance with this standard shall be manufactured from;  
i. Low density polyethylene (PE -LD), linear low -density polyethylene (PE -LLD) 
and their blends;  
 
ii. Ethylene vinyl acetate copolymers (EVAC) and their blends with the PE -LD 
and PE -LLD;  
 
iii. Ethylene butyl acrylate copolymers (EBAK) and their blends with the PE -LD 
and PE -LLD;  
 
iv. Gas barrier polymers, e.g. EVOH or polyamide  
 
 
6. Requirements  
 
6.1 General requirements  
 
6.1.1  Films shall be visibly free of holes, flaws, slackness, wrinkles, stains, foreign matter 
or marks which can impair their serviceability as agreed upon by interested parties.  
 
6.1.2  The film and tube shall be furnished in the form of roll or in any other form as 
agreed between interested parties.  
  
6.2 Specific requirements  
 
6.2.1  Thickness  
 
The thickness tolerance shall be  10% within of the nominal value.  
 
6.2.2  Performance characteristics  
Films shall meet the requirements of physical properties listed in Table 1.  
Table 1: Properties of the film   
  
Properties  Requirements   
Test 
method  Type 1  Type 2  Type 3  Type 4  Type 5  
Tensile strength at break 
(MD, TD), MPa, 
minimum  22 17 20 20 20 ISO 527 -3 
Tensile strain at break, 
%, minimum  
MD 
TD  
400 
500  
300 
400  
350 
450  
350 
450  
350 
450  
ISO 527 -3 
Impact resistance, g, 
minimum  450 200 50 300 50 ISO 7765 -1 
Oxygen transmission 
rate, (cc/m2/day), 
maximum  50 100 ISO 15105 -
2 
Water vapor 
transmission rate 
(cc/m2/day), maximum  10 ISO 2528  
 
7 Storage and handling  
 
7.1 The roll shall be carried, not dragged over the ground or any other surface.  
 
7.2 The film shall be stored in a location protected from direct exposure to sunlight and 
temperature source and rain.  
 
7.3 The duration of storage by the end user shall be contractually limited to less than three 
months. 
 
7.4 Handling should be performed horizontally.  
 
8 Marking and labelling  
 
The film shall be legibly and indelibly marked with the following information;  
 
a) Manufacturer’s name, address and /or trademark;  
 
b) Use of the film: “SILAGE FILM”  
 
c) Type of the film, i.e. Type 1,2,3,4 or 5  
 
d) Nominal thickness of the film;  
  
 e) Year and month of manufacture  
 
f) Recycling symbol.  
g) Plastic identification code or name.  
 
9. Sampling  
 
9.1 Lot 
In any consignment, all rolls of film of the same grade shall be grouped together to 
constit ute a lot.  
9.1.1  Test for determining the conformity of the lot to the requirements of the 
specification shall be done on each lot separately. The number of rolls of the 
film to be selected for this purpose shall be in accordance with column 2 of 
Table 2.  
 
9.1.2  The rolls of films shall be selected at random from the lot.  
 
9.2 Number of Tests and Criteria for Conformity  
 
9.2.1  From each of the roll of the film selected according to 9.1.2 approximately 10 
m2 of the film of full width shall be cut; care being taken to exclude not less than 
2 metre lengths of film (or three full turns of the roll) from either end. The test 
specimens for the various tests shall be cut from different parts of each of the 
10 m2 pieces.  
 
9.2.2  Each of the pieces as obtained in 9.2.1 from a lot shall be examined for general 
requirements (see 6.1). Any piece which does not meet the requirement of any 
of the above characteristics shall be considered as defective.  
 
9.2.3  if the number of defective found (see 9.2.2) is less than or equal to the 
corresponding permissible number of defective given in column 3 of Table 2, 
the lot shall be tested for the remaining requirements of the specification. If the 
number of defective found is more than the corres ponding permissible number 
given in column 3 of Table 2, one more lot of samples may be examined.  
 
9.2.4  The lot having been found satisfactory according to 9.2.3 shall be tested for 
specific requirements (see 6.2). For this purpose, the rolls already tested 
according to 9.2.2 and found satisfactory shall be used for testing any of these 
characteristics. Specimen(s) for these tests shall be cut from 10 m2 piece 
already taken from each roll/folded film selected (see 9.2.1),  
9.2.4.1  The lot shall be deemed to have satisfie d these requirements if all the test 
results for different characteristics given in 9.2.4 are found meeting the relevant 
requirements of the specification.  
  
 9.2.5  The lot shall be declared as conforming to the requirements of the specification, 
if the requiremen ts for various characteristics as given in 9.2.3 and 9.2.4 are 
satisfied.  
 
Table 2 Scale of Sampling and Permissible Number of Defective  
 (Clauses 9.1.1 and 9.2.3)  
Lot Size  Number of 
rolls Permissible number of 
Defectives  
1 1 0 
2 to 15  2 0 
16 to 40  3 0 
41 to 65  5 0 
66 to 
110 7 0 
111 to 
180 10 0 
181 to 
300 15 0 
301 to 
500 25 1