Plastic hydraulic hose assemblies are frequently used in hydraulic systems in different industries. A limited number of data provided by the manufacturer inform the user about safety technical properties: behaviour in the case of failure or ageing, reaction to environmental factors. Further details to assess the safety of hose assemblies are not available. The investigations, initiated by the expert commitee Iron and Metal II, were meant to check compliance of the hose assemblies with the standardised safety requirements in terms of pressure load and to test the hoses' behaviour under workplace-like conditions. The basis for safety technical assessments should thus be broadened.
Impulse tests without bending (in accordance with the German standard DIN 20024 "Fluid systems; hoses and hose assemblies; test methods") and with alternating bending (according to the German standard DIN ISO 26802 "Rubber and plastics hoses and hose assemblies; wire reinforced; hydraulic impulse test with flexing") were conducted to check compliance of new hoses with the applying safety requirements. Workplace-like load was simulated: twisted mounting, damage caused by sharp-edged metal sheets, radiation heat and long-term (several years) storage in cooling lubricants, cutting oils and under workplace conditions. Every load sequence was followed by impulse testing. For comparative reasons, rubber/steel hoses were included in the tests, too.
Plastic hydraulic hose assemblies (type 2 KT) meet the standardised minimum requirements in terms of bursting strength and impulse testing. Compared to rubber/steel hoses, plastic hoses are extremely sensitive to mechanical strain, thermal load and contact with cutting oils. In the case of twisted mounting, sensitivity of plastic hoses is lower than that of rubber/steel hoses. The published criteria enable the user to easily assess the safety properties of plastic hydraulic hose assemblies for the different fields of application.
metal workingType of hazard:
Maschinensicherheit, Physikalische Faktoren, UnfallverhütungDescription, key words:
hydraulic hose assemblies, pressure, load, mechanical, thermal chemical effects