Essential conditions for secured application of hose assemblies

1. Selection of hose and fittings according demand (specification) by medium and application (working circumstances)

• Particles of liquid or solid agents may physically penetrate, respectively cause chemical reactions.
• Physical effects: Causing change in volume of the hose material, consequently causing a change in the characteristics i.e. hardness, tensile strength, elongation etc. (example “popcorning” in steam hoses).
• Chemical effects: Causing change in chemical construction of hose material, causing change in properties (e.g. plasticizers or ageing-protectors are decomposed causing possible spill or leakage).
• Exploratory details can be found in the charts “General properties” and “Chemical resistance tables”.
• The permitted working pressure and vacuum are not to be exceeded.
• The permitted working temperature in interdependence with the medium is not to be exceeded.
• In case of abrasion always consider wear and tear.
• Regular checking of the hose is required.
• Hose assemblies may, in the process of use, never absorb dangerous electrical charges and where applicable the electrical resistance (measured over the hose from fitting to fitting) may not exceed the value of 10⁶ Ω.
• Hoses marked with „Ω“ are consisting of materials already causing conductive properties.
• Hoses marked with „M“ need to be secured by connecting the static wire(s) to the fittings in a permanent way, such in order to assure conductivity.
• The indicated overpressure on the plastic spiral hoses refers to a short-term pressure at 20°C. Multiple overpressure usage will lead to a weakened hose and will also reduce the lifetime of the hose.

2. Professional assembly

• The selection of hose and fittings must be made in correct sizes and attuned to each other.
• Assemblies of fittings may only be executed by experts and is always subjected to prevailing directives.

3. Correct storage

• Always stock the hoses dry and clean.
• Avoid influences from radiation of Ultraviolet and sunshine.
• Store tension and kink free.
• Avoid temperatures under -20°C and over 30°C.

4. Correct utilization

• Hose assemblies must always be installed accessible for persons, in it’s natural position and unobstructed. Take into account that hoses under vacuum suffer from decrease in length.
• Under pressure, change in length and diameter will occur (non-reinforced PVC spiral hoses may elongate to 40% of it’s original length when maximum working pressure is applied).
• Hose lengths may, in essence, not be claimed on their ability of torsion, elongation and pulling strength.
• Hose lengths may not be put under torsion, compression and extension.
• Hose lengths may not be bended below its bending radius, especially not behind the fittings. Here you find details on ‘’bending radius’.
• When required inspect and check electrical resistance of the hose lengths.

5. Registration of procedure of instructions meeting regular education of employees. Readiness and use of appropriate personal safety equipments.

• To handle hose-lengths safely it is necessary to implement technical, personal and organizational measures for protection. Preference must be given to the technical and organizational measures. Should these not avoid all dangers, effective personal safety equipment must be provided and used.

6. Regular inspections

• Hose assemblies must be inspected by an expert prior to putting into use. Regular inspections are recommended then-after (e.g. chemical hoses once a year, steam hoses at least once every six months).
• Essential details of inspection should be:
• Visual inspection of the hose:
  • Sufficiently cleaned before inspection
  • Kinks, bruises and deformations
  • Chemical porosity or mechanical damage to inner tube and/ or cover.
  • Damage, deformation or corrosion to the fittings.
  • Damage, deformation of missing seals and washers.
• Pressure test, leak proof tests:
  • Pores, leaks, kinks, bruises, blisters or deformations.
  • Unacceptable elongation, overextended torsion.
  • Leakage, in hose connection or fitting(s).
• Inspection of electrical conductivity:
  • Testing ability of electrical resistance with “Ω” and “M” hoses.
• Testing results must be documented.

Source: BG Chemie Merkblatt T002 (ZH 1/134)