In the field of industrial fluid transportation, the selection of centrifugal pumps directly affects system efficiency and operational stability. OH1 and OH2, as common structural types of centrifugal pumps, although both belonging to the category of horizontal single-stage centrifugal pumps, have significant differences in design concepts and practical applications. The following is an analysis from four dimensions: structural design, performance parameters, applicable scenarios, and maintenance costs.
The OH1 centrifugal pump adopts a cantilever design, with the impeller directly mounted on the extended end of the motor shaft and supported only by the motor - end bearing. This structure eliminates the need for an independent bearing box for the pump body, resulting in a more compact overall axial dimension, which is suitable for installation environments with limited space. However, the cantilever structure causes the axial force at the impeller to be completely borne by the motor bearing, which is prone to accelerating bearing wear during long - term operation.
The OH2 centrifugal pump is equipped with an independent bearing box, and the impeller is supported by both the pump - end bearing and the motor - end bearing on both sides, forming a double - support structure. This design s
pecifically balances the axial force through the thrust bearing in the bearing box, significantly reducing the load on the motor bearing, and the operational stability is significantly improved, but the overall volume is larger than that of the OH1 type.
Due to structural limitations, the rated working pressure of the OH1 centrifugal pump usually does not exceed 1.6MPa, making it suitable for medium - and low - pressure transportation scenarios; the OH2 type, through enhanced bearing support and sealing design, can withstand a pressure of more than 2.5MPa, and is more suitable for high - pressure pipeline systems.
Under the same flow rate condition, the efficiency curve of the OH2 centrifugal pump is flatter, and the efficiency decays slower when deviating from the design working condition; the OH1 type has higher efficiency near the rated working condition, but its adaptability to variable working conditions is weaker.
Because the OH1 centrifugal pump has no independent bearing box, the bearing replacement requires disassembling the connection between the motor and the pump body, and the single maintenance working hour is longer; however, its structure is simple, and the cost of spare parts is lower. Although the OH2 type has an independently designed bearing box, which makes daily maintenance more convenient and allows for the separate replacement of the pump - end bearing, the purchase cost of special bearings and seals is relatively higher. When selecting the type, it is necessary to comprehensively consider the equipment operation cycle and maintenance budget.
The OH1 type, with its simple structure, is most suitable for "light - duty conditions" such as urban water supply and drainage, agricultural irrigation, which involve low pressure and small flow. Its low purchase and maintenance costs can give full play to its value, making it a cost - effective choice. However, in high - lift and high - speed environments, the service life of the bearing will be significantly reduced due to the cantilever defect. The OH2 type, with its span - support design, has become a long - term reliable choice for "heavy - duty conditions" such as chemical high - pressure processes and power plant boiler water supply. Not only does its service life under high load extend by more than 50% compared with the OH1 type, but also the shaft seal reduces leakage due to small shaft deflection, and it can reduce the fatigue damage of pipelines and foundations by virtue of its low - vibration characteristic.
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