Pressure <140 bar 140 to 210 bar >210 bar Ratiobx = 75 25-40 μm 12-15 μm 6 -12 μm It is recommended to use a filtering systemhaving absolute filtering capability of 5 μmor lower in the systems using sophisticated valve slaves. CleaningAnd Filtering The System It is widely known that most pump early failures are due to contaminated fluids. The extreme reduction of the tolerances required in the design of the pumps, and therefore their operation with minimum clearances, are heavily influenced by a fluid that is not perfectly clean. It is proved that particles circulating in the fluid act as abrasive agents, damaging the surfaces they touch and increasing the quantity of contaminant. For this reason, ensure that system is perfectly clean during startup and keep it clean for its whole operating life. Regular checks should be made for contamination of the oil. Preventive actions include: proper cleaning of the system during assembly, deburring, eliminating the welding scumand fluid filtering before filling up. Starting contamination level of system fluid should not exceed class 18/15 (ref. ISO 4406). Even fresh fluids might exceed this contamination level; therefore always pre-filter the fluid when filling up or topping up the system. Fit a proper tank; its capacity should be proportional to the volume displaced in one working minute. Fluid contamination levels should be monitored by use of correct filter types. Two parameters tell which filter is most suitable: absolute filtering power andbfiltering ratio. Low absolute filtering power and highbfiltering ratio for small particles help ensuring good filtration. It is then very important to limit not only the size of particulate, but also the number of smaller particles that pass through the filter. It goes without saying that with an operating pressure increase and according to the system sophistication degree, filtering should becomemore andmore efficient. The filtering system shall always ensure contamination levels not exceeding the values indicated below: NAS 1638 Class 10 9 8 ISO4406 Class 19/16 18/15 17/14 Hydraulic Fluids Use specific mineral oil based hydraulic fluids of good anti-wear, anti-foaming (rapid deaeration), antioxidant, anti-corrosion and lubricating properties. Fluids should also comply with DIN 51525 and VDMA24317 standards and compliant with 11th stage of FZG test. Fluid kinematic viscosity ranges are of following: allowed value (upon verification) 6 to 500 cSt For the standardmodels, the temperature of the fluid should be between -10°C and +80°C. If fluids other than the above mentioned type are used, please always indicate type of used fluid and operating conditions so that jbj Techniques technical office can advise of possible problems with compatibility or useful life of systemparts. Intake line 0.5 to 1.6m/s Hydraulic systempipes should show no sudden changes of direction, sharp bends and sudden differences in cross-section. They should not be too long or out of proportion. Pipe cross-section should be sized so that fluid velocity does not exceed recommended values. It is advisable to carefully consider the possible diameter reduction of the inlet or outlet pipes fitted on flange fittings. Delivery line 2 to 6m/s Under standard working conditions, intake pipe pressure is lower than atmospheric pressure. The operating inlet pressure should range between 0.7 and 3 bars (absolute). recommended value 10 to 100 cSt Inlet &Delivery Lines value allowed at startup <2000 cSt Inlet Pressure Return line 1.6 to 3m/s Gear Pumps ALP-GHP Series Installation and Running Information 9 www.jbj.co.uk/gear-pumps.html #DriveLineHarmony
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