BS EN 788:1994 pdf free download.Sacks for the transport of food aid Tubular sacks made of composite film.
1 Scope
BS EN 788 specifies the general characteristics, requirements and methods of test for tubular sacks made of composite film, for example PET/AIuIPE.
BS EN 788 applies to tubular sacks made of composite film, for example PET/A1uIPE, for the packaging of foodstuffs with a net filling weight up to 2 000 g and a storage life of at least 1 year in tropical climates of 38 °C and 90 % relative humidity.
The tubular sacks may be used as vacuum or inert gas packages.
The packaging surrounding filled tubular sacks is not covered by this standard.
2 Normative references
BS EN 788 incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to BS EN 788 only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies.
EN 10204:1991, Metallic products — Types of inspection documents.
EN 22233:1992, Packaging— Complete filled transport packages — conditioning for testing.
(ISO 2233:1986)
EN 26590-2:1992, Packaging— Sacks— Vocabulary and types — Part 2: Sacks made from thermoplastic flexible film. (ISO 6590-2:1992)
EN 27023:1992, Packaging — Sacks — Method of sampling empty sacks for testing. (ISO 7023:1983) ISO 186:1985, Paper and board — Sampling to determine average quality.
ISO 1184:1983, Plastics — Determination of tensile properties of films.
ASTM D 3985:81, Standard test method for oxygen gas transmission rate through plastic film and sheeting using a coulometric sensor.
3 Definitions
For the purpose of BS EN 788, the following definitions apply.
NOTE Other terms used in the manufacture of tubular sacks are defined in EN 26590-2:1992.
3.1
composite film
a composite structure manufactured by adhesive bonding or extrusion lamination of at least two sheets of film, for example polyester film, aluminium foil or polyethylene film
3.2
tubular sack
a container made from a web formed by heat-sealing
a longitudinal and bottom seam and closed after
filling with a heat-sealed top seam
3.3
vacuum packed tubular sack
a tubular sack from which the air is evacuated in order to protect the filling material and which is subsequently sealed hermetically
3.4
inert gas filled tubular sack
a tubular sack in which the air is replaced by inert gas, e.g. nitrogen plus carbon dioxide
3.5
heat-sealed seams
longitudinal, bottom and top seams manufactured
by heat-sealing the inner polyethylene piy
4 General characteristics
4.1 Construction
4.1.1 The tubular sacks shall be manufactured from
a flat web of composite film wrapped around a roll,
for example PET/Alu/PE. formed as a flat sack with
a heat sealed longitudinal, bottom and top seam.
4.1.2 Tubular sacks shall be made of only one ply.
4.1.3 The aluminium foil inserted preferably as a protective layer shall be gas tight.
4.2 Dimensions
4.2.1 The dimensions of the tubular sacks shall be aligned with the dimensions of the surrounding packaging.
4.2.2 The dimensions and dimensional tolerances of the tubular sacks should be agreed upon by the purchaser and the supplier.
4.2.3 The dimensions and dimensional tolerances of the tubular sacks shall be recorded in the ordering documents.
4.2.4 The dimensions and the dimensional tolerances of the composite film roll lengths and roll widths shall depend on the specifications of the tubular sack machines and the size of the tubular sacks and be agreed upon by the supplier and the composite film manufacturer.
4.2.5 Where printed composite film is to be processed. the lay-out and the position of the printing shall be agreed upon by the supplier and the composite film manufacturer.
4.2.6 Dimensions and dimensional tolerances of the lay-out and printing shall be recorded in the ordering documents.
4.2.7 The coefficient of sliding friction of the film shall comply with the specifications of the tubular sack machine and be agreed upon by the supplier and the composite film manufacturer and recorded in the ordering documents.
4.3 Food compatibility
Sacks which come in contact with foodstuffs shall meet the legal requirements of the CEN member states which are applicable to them.
5 Test methods and requirements
5.1 Sampling
5.1.1 The composite film shall be sampled in accordance with ISO 186:1985, where a roll of composite film shall be regarded as a packaging unit as shown in Table 1 of ISO 186:1985.
5.1.2 Tubular sacks shall be sampled in accordance with EN 27023. At least 30 units shall be sampled.
5.1.3 Samples shall be taken on the day that the empty tubular sacks are ready for dispatch at the supplier’s.
5.1.4 If. as a result of an accident during sampling or testing, resampling is necessary, a new sample shall be taken by the same procedure. Selection may then, however, be made from the same units as before unless agreed otherwise.
5.2 Conditioning
5.2.1 Before testing, all samples shall be conditioned in accordance with EN 22233:1986 condition G (temperature + 23 °C ± 2 °C, relative humidity 50 % ± 5 %).
5.2.2 The minimum period for conditioning shall be not less than 8 h.
5.2.3 The various tests described below shall be carried out in the same atmospheric conditions as used for conditioning. If this is not possible, the tests shall commence within 10 mm of conditioning.
5.3 Test date
All tests shall be carried out within 4 weeks of the date that the tubular sacks are ready for dispatch at the supplier’s.
5.4 Tests
5.4.1 Determination of the tensile stress at break and elongation at break of the composite film
The tensile stress and elongation at break in a longitudinal and transverse direction shall be determined in accordance with ISO 1184:1983 using 15 mm wide test strips, with a gauge length of 100 mm and a testing speed of 100 mm/mm, until total rupture of the composite film.
5.4.2 Adhesion of the co,nposite film Adhesion in a longitudinal and transverse direction shall be determined between the outer and middle ply (e.g. PET/Alu) and between the inner and middle ply (e.g. Alu/PE) in accordance with ISO 1184:1983 on 15 mm wide and 200 mm long test strips and a testing speed of 100 mmlmin, the clamping of the test strip being in order for the plies to be stressed to peel. From both longitudinal and transverse direction 5 test strips shall be taken.
Before testing, the layers of which the adhesion are to be determined shall be separated over a length of at least 40 mm. When necessary a suitable solvent can be used which shall be removed before testing. During the test the part of the composite film which is not separated shall be kept perpendicular to the direction of pull.
5.4.3 Oxygen permeability of the composite film The oxygen permeability shall be determined at 23 °C and 50 % relative humidity in accordance with ASTM D :3985:81.
5.4.4 Heat sealed seam strength of tubular sacks
The strength of the heat-sealed seams shall be determined using the tensile test described in ISO 1184:1983 on 15 mm wide test strips, with a gauge length of 50 mm. a heat-sealed seam lying transversely to the direction of pull and in the middle of the test strip, the clamping of the test strip being in order for the heat-sealed seam to be stressed to peel, and with testing speed
of 100 mm/mm.