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Your Specialists in High-Pressure HoseSM

Frequently asked questions

What is the breaking strength (resistance to breaking) of a hose? How strongly may you pull a hose?

  • High-pressure hoses are constructed in a way to withstand max. internal pressures. For the design of the hose the longitudinal tensile load is not taken into consideration and, therefore, it must be kept as low as possible by appropriate measures while the hose is being used.
  • Tensile loads of more than 250 N must be ruled out by appropriate constructive means.
  • It is not permitted to use high pressure hose as a load-bearing component for taking up tensile loads, lateral powers or torsion forces.


How many cycles does hose type XY reach in our internal impulse test bench?

  • All SPIR STAR® hose types have to pass a strict qualification test procedure including an impulse test before being released for sale.
According to which standard are the SPIR STAR® hoses produced?

  • Spiralized high-pressure hose with thermoplastic inner liner has been developed by SPIR STAR® because the standard hoses according to SAE, DIN, EN etc. did not fulfil the requirements regarding pressure, temperature, chemical resistance, permeation, weight, volumetric expansion etc. requested by the customers.
  • SPIR STAR® hoses exceed standard hoses in all essential requirements by far.
  • To make it possible to produce this unique product, many years of development were necessary. Some manufacturing procedures had to be developed first and existing machinery had to be converted and optimized.
  • For that reasons SPIR STAR® high pressure hose cannot be compared with any standard hose according to SAE, DIN, EN etc.


Are our hose assemblies also available with fittings made of V4A stainless steel?

  • The decision whether or not V4A stainless steel fittings may be used depends mainly on the working pressure. SPIR STAR® high-pressure hoses are designed for working pressures of up to 3,200 bar. These high pressures make special demands on the mechanical properties (tensile strength, stretch at break etc.) of the fitting material. For our 6 and 8 layer hoses, therefore, we normally use for the nipple high-alloy special steels with a tensile strength of more the 1,000 N/mm². V4A steel does not achieve a tensile strength like this. For that reason the safe use of V4A, particularly with the 6 and 8 layer hoses, in individual cases has to be checked by burst and impulse pressure tests. In any case the use of V4A reduces the service life of a hose assembly. Therefore, V4A should only be used if it is absolutely necessary for the application. Furthermore, for crimping fittings made of V4A it has to be taken into account that the material is more resilient and, therefore, a higher Adjust Factor (approx. 0.1 - 0.3 mm) must be used.

Are we allowed to issue a CE Certificate of Conformity (according to the Directives on Machinery and Machinery working under pressure respectively)? or
Are we allowed to fix a CE Conformity mark to our hose?


  • Our high-pressure hoses do not belong in the scope of application of the Directives on Machinery and Machinery working under pressure respectively. For that reason we must not issue CE Certificates of Conformity or fix a CE Conformity mark to our hose.

  • If a customer installs hoses in a machine that is subject to compulsory CE labelling, the manufacturer of the machine has to see to it that all the requirements of the Directive on Machinery as well as any other applicable standards are met, and fix the appropriate label(s).

Are we able to offer hoses with a conductive outer cover according to EN 13463-1 for being used in mining or in locations subject to explosion hazard?


  • Our standard high pressure hoses are not appropriate for being used in mining or in locations subject to explosion hazard!

  • Upon request, however, we can use conductive polyamide as an outer cover material. This outer cover material has an insulating resistance of 10³ Ohm, which has been determined with test pieces according to DIN EN 50014. Thus the resistance is below the value of 106 Ohm requested in accordance with EN 13463-1 point 7.4.3 clause a) (for equipment belonging to group I) and point 7.4.4 clause a) (for equipment belonging to group II) respectively.


Are our outer cover materials UV stabilized?

  • Our PA12 outer cover material is UV stabilized according to DIN 73378.



May our hoses be used with a safety factor of less than 1:2.5?

Under the following conditions it is possible to reduce the safety factor to a value of max. 1:2:

  • 1) The burden is so low that an acceptable service life is achieved (e.g. static applications without pressure pulsation). In individual cases the customer has to determine this by means of testing. It is needless to say that claims because of too short a service life will then be impossible.

  • 2) The user has to make adequate arrangements so that in case of a hose failure people will not be put at risk. This can be implemented e.g. by means of a closed chamber with a safety switch at the door that will reduce the pressure to 0 bar if the door is unlocked.



How to determine the minimum bend radius of ultra-high pressure hoses


  • The minimum bend radius of hydraulic rubber hoses is determined by a standardized procedure using the flattening. This approach cannot be used with high-pressure hoses because of their greater stability.
    For that reason, the manufacturers of high-pressure hoses determine the minimum bend radius at their own discretion as follows:
    At first, the designing engineer selects a minimum bend radius based on experience. By means of impulse tests this minimum bend radius is verified and adjusted if necessary.
    In this connection it is important to know that there does not exist a predetermined and rigid limit for the bend radius but rather a basic relationship between the bend and the impulse resistance.
    Any bending, even one that does not exceed the minimum bend radius, causes within the material of the inner liner of the high-pressure hose a tensile stress on the outside of the curve and a compressive stress on the inside. These stresses add up with the axial and the radial stresses caused by the working pressure reducing that way the impulse resistance. This condition is referred to as multi-axial state of stresses.
    The smaller the bend radius the bigger the stresses caused in the material of the inner liner and the smaller the impulse resistance of the high-pressure hose. If one shows this on a diagram, a declining curve will appear, the so called Wöhler- or stress-number curve (S/N-curve). This curve runs asymptotically towards a limit, the minimum bend radius. This limit indicates the bend radius where the impulse resistance of the hose installed in a bent position ceases to show any differences from the one of a high-pressure hose installed in a straight position.
     
  • As it takes a great effort to identify the stress-number curve and with little accuracy at that the scope of discretion for the determination of the minimum bend radius is quite big. Therefore, the minimum bend radius indicated in the catalogue reflects to a great extent the readiness of the manufacturer to assume risk.


How to determine the recommended working temperature of high-pressure hoses?


  • It is generally accepted that the higher the working temperature the shorter the service life of high-pressure hoses. But this effect occurs only above a certain temperature limit. This temperature limit can be determined using impulse tests. For POM and PA the influence of temperature on the service life is low up to a temperature of 60°C. Above 60°C the service life decreases noticeably. For that reason SPIR STAR recommends not to exceed the temperature limit of 60°C during operation.

Where can one obtain training materials for the correct handling of water jet cleaning equipment?


  • WJTA (Water Jet Technology Association) offer training materials for the correct handling of water jet cleaning equipment.
    Inter alia there are available training videos, information brochures and safety cards. These publications are available in English and Spanish.

  • Contact:
    WJTA
    906, Olive Street
    Suite 1200, St. Louis
    MO 63101-1448 USA
    Fax: +1 (314) 241-1449
    Tel.: +1 (314) 241-1445
    http://www.wjta.org/


What are the differences between the documents DIN EN 10204-2.2, -2.3 and 3.1?


  • DIN EN 10204-2.2:
    Test report - Confirmation that the product complies with the order based on the results of nonspecific tests. This document is issued by the manufacturer.

  • DIN EN 10204-2.3:
    Specific test report - Confirmation that the product complies with the order based on the results of specific tests. This document is issued by the manufacturer.

  • DIN EN 10204-3.1:
    Inspection Certificate 3.1 - Confirmation that the product complies with the order based on the results of specific tests. This document is issued by an inspection representative of the manufacturer who works independently from the manufacturing department.

  • The Specific test report according to DIN EN 10204-2.3 was deleted from the DIN EN 10204 standard in January 2005. Nevertheless, many companies still issue this document for whatever reason.

Certified to the
DIN EN 1829-2

Type 8/6H, 8/6UHP and 8/6UHP-X.

 

 

 


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