NORRES Schlauchtechnik / Industrial Hoses / Product Quality /
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Pre-PUR^®

Polyurethanes are not all the same! For many of its hoses, NORRES uses special ester-polyurethane and ether-polyurethane mixtures that we distinguish with the name Pre-PUR^®. Compared to many other plastics, rubber formulations and “simple” polyurethanes, the block copolymers, which consist of hard and soft Pre-PUR^® segments, have superior properties.

Our hoses made from Pre-PUR^® raw materials differ as follows from many of the hoses commercially available:

• Higher mechanical stability
• Less abrasion
• Improved chemical and hydrolytic stability
• Higher softening points
  → greater residual strength at high temperatures
  → higher compression strength
  → greater safety due to material stability
• Better hot air aging properties
• Better flexibility at low temperatures
  → lower “bending force” at low temperatures
  → lower risk of bending fracture at low temperatures

detailed description of Pre-PUR^®

 

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HT-PUR

Continuous operating temperatures of 125°C are often demanded of the hoses used in plastics production or on printing presses and compressors. NORRES has developed a new polyurethane type based on the premium polyurethane Pre-PUR^® that is more resistant to heat and less susceptible to ageing than other materials.

The polymer is cross linked by NORRES in an innovative process to create a material that shows a 40 percent improvement in mechanical stability during heat exposure. NORRES hoses with the HT-PUR symbol can be heated to a continuous operating temperature of 125°C and withstand peaks of up to 150°C.

Advantages of HT-PUR hoses at a glance:

• Longer service life
• Less wear
• High compressive strength at higher temperatures
  → Lower operating costs
• Good resistance to chemicals, oil and petrol
• Lighter, more flexible and cheaper than other materials such as metal
• Capable of electrostatic discharge

 

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Abrasion-resistant

The particularly high quality mixtures of PUR materials, as well as the optimized, reinforced hose designs from NORRES, result in substantially less wear in pumping and transport processes than with many other hoses. These NORRES hoses are specially developed for long service life for the delivery of highly abrasive media. Compared with similar grades of hose, they are distinguished by a number of special characteristics, including:

• Selective reinforcement of the wall geometry at the primary points of wear. We consistently achieve surprisingly high service life for our hoses through continual optimization of their design geometries.
• In applications, greatly increased temperatures can arise due to friction from the pumping medium. Thermoplastic synthetic materials soften at higher temperatures, leading to a loss of strength and increased abrasion. In vacuum operation this leads to an pronounced axial contraction, an increase in the rippling of the interior wall and thus a further increase in abrasion.
  NORRES uses material mixtures with high dimensional stability at high temperatures for polyurethane hoses intended for these applications.
• The profile geometries of NORRES PUR hoses are optimized to give the products outstanding axial stiffness while maintaining excellent flexibility. Less interior rippling in vacuum applications means longer service life.
• These hoses are made from raw materials with particularly high mechanical strength and special additives, resulting in
  • Very high abrasion resistance
   → less wear
   → long service life
  • very high tensile strength
   → less change in the axial length of the hose during the application
   → less interior rippling of the hose due to change in length
   → long service life
  • Additional reductions in wear due to the special additives

 

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Crush-Proof

NORRES hoses with this symbol are specially designed for workshop use and laying on floors. They are able to resist crushing to some extent or entirely when driven over or stepped on. Please refer to the relevant product description for more details.



 

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Interior smoothness

Many hoses from NORRES have outstanding interior smoothness and are thus optimized for flow. They have the following advantages:

• Very high delivery rates
• Low pressure loss
  → reduction of blower power requirements
  → lower operating costs
• Gentler material delivery
• Low wear and therefore longer service life

 

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High flexibility

This symbol is only used for NORRES hoses that are highly flexible and have the following characteristics:

• Minimal counterforce and restoring force when bent
• Optimal for applications such as suction arms

 

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Ether-PUR

For many hoses, NORRES uses a special, high quality ether-polyurethane instead of the ester-polyurethane frequently used for commercial applications. Hoses of this type have the following advantages:

• Resistant to microbes
  (This is critical for extended contact with soil or similar substances or heavy contamination under conditions favourable to microbes. The chemical structure of ether-polyurethanes gives the materials permanent resistance to microbial attack. We believe this is clearly a better solution than ester-polyurethanes that are often stabilized with for health not completely harmless additives for this purpose. With these ester-polyurethanes there is a risk that the additive will leach out, causing the level to fall below that required for protection as the additive migrates to the surface of the hose and comes in contact with the user and the material transported.)
• Resistant to hydrolysis
  (This is critical for wet applications at higher temperatures and for use in tropical climates.)
• Better chemical stability than comparable ester-polyurethanes
• Better flexibility at low temperatures than comparable ester-polyurethanes

 

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Approvals for use with foodstuffs

NORRES hoses with this symbol have one or more national and/or international approvals and certifications of conformity that allow them to be used in food applications. Please refer to the relevant product description for more details.



 

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Free of softener

Today, softeners are often undesirable in hoses for a number of different reasons:

• Embrittled material due to migration can result in premature failure
• Certain plasticisers are classified as possible health hazards
• Softener are often banned in certain applications
• Softener can be problematic in case of fire, leading to high clean-up costs
• Disposal problems arise in many areas

NORRES hoses with this symbol are 100% free of softener

 

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Flame retardant

NORRES hoses with this designation have one or more national and/or international approvals classifying them as having low flammability or as self-extinguishing and/or fall below specified rates of burning.



 

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Partially coloured

Strengthen your market position by consistent application of your corporate design and differentiate yourself from the competition. Create a unique "look" to secure after-sales business and reduce product liability risks with an unfalsifiable appearance.

Using a patented production method, AIRDUC^® and PROTAPE^® hoses can also be coloured in the bead area according to your specifications. Compared with completely coloured hoses, the partially coloured design makes the impression of a significantly more flexible, lighter product. Moreover, as with transparent hoses, it is possible to observe processes directly. Please note the dedicated subsection.

 

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PVC-free

Hoses with a PVC content, which could not easily and immediately be recognized (such as polyurethane hoses with PVC-coated wires), are also offered on the market.
Increasingly, PVC is becoming undesirable for the following reasons:

• Disposal problems (PVC is classified as hazardous waste in many cases)
• High clean-up costs after a fire
• Many customers have issued a general prohibition against the use of PVC
• Import duties on PVC products in certain countries
• The plasticizers are classified as possible health hazards in some cases

NORRES hoses with this symbol are 100% PVC-free.

 

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Electro-Static Discharge

When pumping solid materials and fluids through tube and hoses that can store charge, friction between the material conveyed and the wall as well as friction within the medium can cause a build-up of electrostatic charge (=charge separation). AIRDUC^®, PROTAPE^® (except PROTAPE^® MEMORY) and BARDUC hoses from NORRES have a steel wire embedded in the hose wall that enables it to be discharged and provides the following advantages:

• Avoidance of static charge accumulation and discharges of the hose or pumping medium that may lead to ignition
• Possible startle reactions from electrostatic shock with body contact that may lead to accidents are largely avoided
• Fewer process disruptions due to material adherence to the walls of the hose
• Significantly reduced disruption of measuring and control equipment
• NORRES hoses that are classified as electro-static dischargeable according to the new German trade association regulation No. 132 (BGR 132, formerly ZH1/200) are marked with this symbol. A prerequisite for this is the grounding of the hose by exposing the steel coil and then connecting it to the conductive fittings.

Please refer to the relevant product description for more details and the technical appendix.
 

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Antistatic or electrically conductive hoses

According to the new ATEX guideline and the German BGR 132, electrically conductive hoses should be used in areas where the danger of explosion exists. Products of this type are distinguished by a special symbol.

Please refer to the relevant product description for more details and the technical appendix.

 

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Special wire adhesion

Many hose types are designed with the spring steel wire firmly embedded in the wall. This strong adhesion is a key prerequisite of the product’s stability, resistance to overpressure and axial stiffness, which in turn have an important influence on hose service life. The operating conditions, for example oils or solvents diffusing into the wall, a combination of mechanical and dynamic loads and especially high or low temperatures, frequently represent a formidable obstacle to achieving permanent adhesion between the spring steel wire and the wall.

Our longstanding experience has taught us that detached wires provoke increased and asymmetric rippling of the hose, usually resulting in a significantly shorter service life, substantially higher pressure losses and long-term disruptions to the delivery process.

Hoses manufactured using our special, highly advanced, multistage adhesion process are marked with this symbol. The exceptionally long service life realised with these products – even when subjected to severe combined loads – would otherwise remain unattainable.

 

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Permanently antistatic

In the past, hoses with antistatic properties were generally manufactured using an additive that migrated over time, so that the material’s antistaticness was gradually lost. The desired antistatic properties could often only be guaranteed if the ambient air was sufficiently humid.

Thanks to a novel, innovative material from NORRES, all hoses marked with this symbol are permanently antistatic. Their antistatic properties are not dependent on the relative humidity nor does their effect deteriorate due to migration.

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