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Choose the right rubber hose
Use of right rubber hoses and connectorsensures safety of the entire hydraulic system, reasonable space layout and better cost control.
I.Rubber hoses should be selected according to the desired purposes.
Hose performance also varies by the materials used in hose production. For example, HP hoses used in construction and in mining industries are similar in nature but provide different performances:
1. In comparison with HP hoses for use in mining industry, hoses for construction have higher rubber content and better oil resistance and are mainly used for delivery of oilproducts,therefore they are also called oil hoses in many places. HP hoses for mining use usually provide better resistance to emulsion prepared by oil and water at certain ratio.
2. Both HP hoses are also different in properties of theirouterrubber layers. HP hoses for construction industryprovidebetter weather resistance since they are more likely used outdoor. HP hoses provide better resistance to static electricity and flame, because no static charge is allowed on the HP hoses in the mine, which may accumulate and cause sparks and explosion.
II.Rubber hoses should also be selected according to the media they deliver.
If special hydraulic mediaareused, the usermust make sure that it is compatible with the hose assembly and theinnerandouterlayers, connectors and O-rings of such hoses. To avoid accidents, please consult us in advance, if drugs with strong toxicity, highly concentrated acid or alkali liquidareused.
Since the pressures in hydraulic systemaredynamic and peak pressure value may be higher than maximum design pressure of the system when surge pressure occurs. However, most hydraulic systems are equipped with overflow valves,therefore the surge pressure will not cause severe impact to hosefatigue life.For hydraulic systems with frequent surge pressure, impulse resistant hoses are recommended.
IV. Comprehensive consideration of operating environment as well as hose type, material and sealing materials.
Operating environment includes the temperature range, presence of strong light, heat source, ozone, corrosion, sparks, dust and extra space, possibilities of contact with sharp objects as well as mediatemperature and concentration.Please contact us, if you have any question as to applicability of hoses in special conditions.
V. Select hoses with right inner diameter according to design flow rate.
Small hose diameter increases flow rate of media in the hose, generates heat and reduces system efficiency and may cause significant pressure drop, which may affect performance of the entire system; however large hosediameterincreases costs. Special attentions shouldpaidto outer diameters, if the hoses are fixed by clamps or go through steel plates. According to design flow rate, inner diameter d ≥1.13, wherein: Q- liquid flow quantity, m³/s, V- flow rate, m/s, recommended flow rate: V≤3~6m/s, for HP oil hose (The larger d value is recommended in conditions with high pressure, short hose length or low oil viscosity, otherwise the smaller d value should be used); and V≤1.5~2.5m/s, for return hose.
VI. Bending radius of hoses.
Bending radius R refers to the (minimal) radius, in which the hose can bend but will not damage or reduce itsservice life. As for a piece of hose, R is a fixed value and in calculation, the hose length should be reduced by crimping length at the connector position. Bending radius in use should in no case smaller that the R value, to avoid damage to hose structure.
VII. Hoses must be in proper length and match the assembly profile and sizes designated according to piping properties.
Rubber hosesmay expand or contract as a result of internal pressure and mechanical movement and their lengths may also vary (-4%~+2%), therefore sufficient length should be reserved for piping purpose.
VIII. Suitable connecting methods. The connector layout and overall hose assembly angle should be determined by the hydraulic pressure level.
Rubber hoses are commonly connected by threads, flange or clamps. There are many types of connectors, such as SAE flange connector, connectors with internal or external threads, connectors in 90°/45° angles, etc. In pipingprocess, theouterrubber layer needs or does not need to be removed from the hose, and in caseouterrubber layer needs to be removed, the groove should not be very sharp and improper size will damage the wire reinforcement layer. Please make sure connectors with the same threads are used, and it is preferred that male and female connectors of a same brand are used. If mixed use of products of differentbrands,please consult your supplier and use them after confirmation is received. Nut connection is commonly adopted because of its easy operation and low costs, however attentions should be paid to loosening nuts where there is excess vibration, in which case flange connection is another option.