SN Vertical Three-Screw Pump

Updated: 2026-07-15

Overview

The SN vertical three-screw pump is a positive displacement pump designed for handling medium- to high-viscosity fluids. Its vertical configuration saves space and is ideal for installations with limited floor area. The pump consists of one driven screw and two idler screws, which rotate within a precisely machined stator to create a smooth, pulsation-free flow. Widely used in industries like petroleum, chemical processing, and shipbuilding, this pump excels in applications requiring steady pressure and high efficiency. Its ability to handle fluids with varying viscosities makes it versatile for both light and heavy oils.

Structure and Working Principle

The pump comprises three main components: the driving screw, idler screws, and stator housing. The driving screw is connected to the motor, while the idler screws rotate in opposition, creating sealed chambers that move fluid axially. The vertical design ensures compactness and simplifies piping arrangements. As the screws rotate, fluid is trapped in the cavities between the screws and stator, transported from the suction to the discharge port with minimal turbulence. This mechanism ensures low shear and consistent flow, making it suitable for shear-sensitive fluids like polymers or emulsified oils.

Key Features

The SN vertical three-screw pump is renowned for its high volumetric efficiency, often exceeding 90%, due to minimal internal leakage. Its self-priming capability allows it to handle gases and vapors without cavitation, reducing downtime in intermittent operations. Other features include low noise levels (<75 dB) and vibration, thanks to balanced rotor dynamics. The pump's modular design facilitates easy maintenance, with replaceable sleeves and bearings. Optional materials like duplex stainless steel extend its use in corrosive environments.

Application Areas

Common applications include fuel transfer in refineries, hydraulic systems in industrial machinery, and lubricating oil circulation in power plants. In marine settings, it is used for cargo pumping and bilge handling due to its reliability under harsh conditions. The pump also serves in chemical processing for transferring resins, solvents, and adhesives. Its ability to handle abrasive fluids (with hardened screws) makes it suitable for mining and pulp/paper industries.

Maintenance and Precautions

Regular maintenance includes checking screw wear, seal integrity, and alignment. Replace worn screws or seals promptly to avoid efficiency loss. Use compatible fluids to prevent stator swelling or screw corrosion. Avoid dry running, which can damage the stator and screws. Install pressure relief valves to protect against overpressure. For cold starts, preheat viscous fluids to reduce motor load.

B2B Procurement Guide

When procuring, specify fluid properties (viscosity, temperature, abrasiveness), flow rate (m³/h), and pressure requirements (bar). Confirm material compatibility (e.g., stainless steel for corrosive fluids). Compare lead times and after-sales support, as custom configurations may take longer. Request performance curves and efficiency data. For bulk orders, negotiate warranties and spare-part availability.