General Information
SN pumps belong to the category of general-purpose pumps. They are designed for pumping clean or slightly contaminated, chemically neutral, low-viscosity liquids with temperatures up to 100 °C. All produced SN pumps can be grouped together, sharing several common structural features: the presence of a semi-spiral inlet, a spiral outlet, and a transfer channel; a multistage design that allows the pump to achieve high discharge pressures at high flow rates.
SN pumps are centrifugal, horizontally oriented, spiral type pumps with a horizontal split casing and transfer channels. They are two- or four-stage pumps with single-entry impellers symmetrically positioned on the shaft.
Modernization and Improvement
The modernization and improvement of SN pump designs are aimed at enhancing efficiency, energy efficiency, reliability, reducing energy consumption, and material intensity. The main directions of improvement include:
- Improving the flow part.
- Increasing the erosion resistance of flow part components.
- Improving the design of bearings and other units.
- Using mechanical seals.
- Reducing noise and vibration levels.
- Extending the maintenance interval.
- Increasing the service life of the pump.
Special Reliability Requirements
The application areas and operating conditions of SN pumps define the main requirements for their design:
- Ensuring high reliability and extending the service life (mean time between overhauls should be at least 20,000-32,000 hours).
- Ensuring external tightness.
- A stable, continuously decreasing head characteristic over the range of flows from 20% to 110% of the nominal value to ensure stable parallel operation in a common network.
The range of use of SN pump is expanded by trimming the impellers by no more than 10% of their original diameter, with the efficiency drop not exceeding 3%.
Moreover, the reliability and energy efficiency of SN pump operation are directly influenced by:
- Proper selection of the SN pump according to the required network parameters.
- Consideration of operational features and integration into the technological scheme of the pumping equipment.
- Precision and quality of manufacturing.
- Qualified installation and subsequent operation.
Meeting these requirements will increase the reliability and efficiency of the equipment by 15-20%, which is a very high indicator and a critically important factor in the operation of the entire pumping unit.
Specific Factors in SN Pump Design
SN pumps must operate reliably in automatic mode without constant attendance and ensure reliable operation when integrated into a common network. The main design requirements for SN pumps include:
- High reliability and cost-effectiveness.
- Extended range of use due to impeller trimming.
- Long service life.
- Dynamic stability across the entire operating range.
- A stable, continuously decreasing head characteristic to ensure stable parallel operation.
- Correct selection of materials for the main parts to provide the necessary service life under operating conditions.
- Selection of the appropriate type of mechanical seal.
- High degree of standardization.
- Ease of assembly, disassembly, maintenance, and high maintainability in operational conditions.
Key Characteristics of SN Pumps by Modification
- Flow rate: from 360 m³/h to 3000 m³/h.
- Head: from 83 m to 380 m.
- Efficiency: from 70% to 81%.
- Motor power (equivalent): from 132 kW to 2500 kW.
- Pump weight: from 1220 kg to 15850 kg.
- Weight of the complete unit: from 2525 kg to 4740 kg.
Applications of SN Pumps
SN pumps and pump units based on them are designed for pumping water and liquids with similar properties to water in terms of viscosity and chemical activity, with temperatures up to 100 °C, containing solid particles not exceeding 0.05% by mass, with a maximum size of 0.2 mm, and a microhardness not exceeding 6.5 MPa (650 kgf/mm²). They are used in water supply systems for industrial and municipal facilities, agriculture, and land reclamation for irrigation and drainage, among other applications.
Technical Specifications and Performance Parameters of SN Pumps
Conditional designation of the pump: SN – centrifugal pump; 400 – flow rate in m³/h; 105 – head in meters; a, b – impeller trimming.
