Vetus Poly-wood Instructions D'installation page 9

1 Characteristics of Poly-wood
1.1 Resistance to chemicals and other media
Due to it's non-polar structure the paroffin hydrocarbons, Poly-
wood has an exceptionally high molecular mass. This makes it
highly resistant to chemicals and other media. It is resistant to
aqueous solutions of salt, acids and alkalis.
Poly-wood has a tendency to stress-cracking, especially due to
internal mechanical strains. It is important for designers to use
Poly-wood in low stress applications.
High temperature can affect chemical resistance to a marked
degree, depending on the surrounding medium. Account must
therefore be taken of this in designing installations for the chem-
ical industry.
Poly-wood is resistant to many solvents up to 60˚C, but is how-
ever penetrated by aromatic and halogenised hydrocarbons
and certain oils, greases and waxes. This penetration is only
very slight up to 30˚C.
Poly-wood has little or no resistanco to strong oxidants such as
nitric (V) acid, ozone, fuming sulphuric acid, hydrogen peroxide
or halogens!
1.2 Resistance to water vapour and gases
Poly-wood is water-repellent. It does not swell when stored in
water.
There is a certain permeability to gases: for water vapour this is
very slight, but very high for O
ous substances.
1.3 Weathering resistance
Poly-wood is resistent to the elements, including UV light (UV
stabilisers are added to Poly-wood).
However, Poly-wood exposed to sunlight in the open air for Iong
periods can be affected, especially by the UV element in sun-
light and acid in the atmosphere. These factors start physical-
chemical processes with the following consequences:
- discoloration (often yellowish)
- embrittlement (loss of toughness)
- loss of mechanical properties.
Poly-wood
and CO as well as many odor-
2 2
1.4 Fire behaviour
Combustibility is often a technical problem with plastics and an
obstacle to their use. Various test methods are used to classify
combustibility. DIN 4102 subdivides materiels into combustible
and non-combustible. Poly-wood is a normally combustible
plastic. DIN 4102 places all combustible materials in Class B,
subdivided as follows:
B1 - slightly inflammable
B2 - normally inflammable
B3 - highly inflammable
Oxygen content is another guide to inflammability. This test as
per ASTM 2863 shows how much oxygen a plastic requires to
catch fire and continue to burn. The number gives the oxygen
concentration (vol. %) in a nitrogen/oxygen mix necessary to
maintain combustion.
Poly-wood fire behaviour:
Behaviour in fire DIN 4102
UL94
Oxygen index
External ignition
Self ignition
1.5 Electrical properties
Poly-wood is usually a good electrical insulator. This property is
put to specific use in many applications, however, there are
many known applications which require electrical conductivity
or anti-static behaviour. Electrical charges on the surface of nor-
mal plastics can produce a potential of several kiloVolts and
sparking can couse dust explosions. Gas-air mixes, and to a
lesser extent dust-air mixes, quickly reach minimum ignition
energies.
Many modern electronic components can be damaged by elec-
trostatit charge. For example, conveyor belts for such compo-
nents should not be insulated, they must be able to conduct
electric energy away.
1.6 Suitability for use with foodstuffs
The German Health Office (BGVV) in its Recommendation III on
PE advises use of PE to manufacture consumer goods under
the meaning of Section 5 Part 1 No. 1 of the Food and
Consumer Goods Law (LMBG).
Poly-wood does comply with this recommendation.
With regard to the colouring used, German Health Office
Recommendation IX 'Colouring agents for Colouring Plastics'
should also be consulted.
Materials which are safe in contact with foods can also be used
in contact with drinking water. The 'KTW' recommendation on
plastics and drinking water should be consulted in any deci-
sion.
ENGLISH
B2
HB
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