Flygt N 3531

The Flygt N 3531 series manages large volumes of water in wastewater, stormwater, treatment and industrial applications. Industry-leading self-cleaning N-hydraulics help ensure optimal energy consumption, extended asset life, and fewer pump station visits to minimize operational costs and environmental impact.

N 3531 pumps are available with Hard-Iron, grey iron, or stainless steel impellers; in explosion-proof and standard versions; and for submersible or dry, vertical or horizontal installation (configurations P, T and Z).

Self-cleaning N-technology impeller

Flygt N-technology hydraulics pair backswept leading edges on the impeller vanes with a stationary relief groove to provide a mechanically self-cleaning hydraulic design. The backswept leading edges sweep solids away from the impeller hub toward the perimeter of the inlet, where they are caught inside the relief groove and pushed out of the pump. The result is clog-free pumping that reduces call-out costs by up to 40% and energy consumption by up to 25%, compared to pumps with conventional impellers. A sludge concentration up to 8% can easily be pumped.

Flygt’s Hard-Iron material (60 HRC) delivers prolonged impeller life in even the toughest wastewater applications.  

State-of-the-art internal cooling system

Flygt N 3531 pumps are available with Flygt’s internal closed-loop cooling system, which prevents motor overheating in both submersible and dry installations. The system circulates a freeze-proof glycol cooling liquid around the inner and outer cooling jackets to transfer the heat to the pumped media. The heat exchange zones around the stator and seal housing covers are designed to optimize the flow characteristics and maximize cooling efficiency. 

Because the cooling system is completely sealed off, it remains insensitive to any impurities in the pumped media.

Designed for extended service life  

Flygt N 3531 are designed with robust, reliable components to provide uninterrupted service and minimize maintenance call-outs. 

• Self-cleaning N-impeller in Hard-Iron, hardened grey iron or duplex stainless steel 
• Replaceable wear ring in Hard-Iron or grey iron 
• Short shaft overhang, reducing shaft deflection and increasing seal and bearing life
• Motor designed for submersible use, with Class H insulation and heat losses concentrated around the stator core for improved cooling properties
  • Option of medium voltage motor up to 6.6 kV to reduce current and motor cable size
• Two sets of mechanical shaft seals that work independently, available in tungsten carbide (WCCR) or silicon carbide (SiC) 
• Active Seal micro-pumping grooves on the inner seal for zero leakage into the motor 
• Thermal sensors in the stator windings; analog temperature sensor for the lower bearing; leakage sensors in the stator housing and junction box; and 3-axis vibration sensor – all as standard. Temperature sensor for the upper bearing as an option
• Flexible cooling options, including internal closed-loop cooling, direct cooling or for warm-liquid applications, external cooling
• SUBCAB^® motor cable specially developed for submersible use
• Flygt MAS 801 pump monitoring system option for a proactive approach to pump station diagnostics

Submersible and dry installation options

Flygt N-technology pumps can be installed in either wet or dry pits. Flygt installation packages include key accessories and components to meet site-specific requirements and reduce installation costs.

Wet pit (P)

Semi-permanent, submersible pump installation. Wet pit arrangement with the pump installed on twin guide bars with automatic connection to the discharge pipe.

Dry installation vertical (T)

Vertical, permanent, dry pump installation. The submersible pump is installed in a dry pit, with flange connection to suction and discharge piping.

Dry installation horizontal (Z)

Horizontal, permanent, dry pump installation. The submersible pump is installed in a dry pit, with flange connection to suction and discharge piping. Optional sled mounting system provides safe, easy access for servicing the drive unit and impeller.

Take advantage of Flygt engineering expertise

Are you getting the most out of your pump station design? If you have questions about fluid dynamics, sump optimization, water calculations, system analysis or more, we can help. 

The Flygt team has decades of expertise and can support intricate custom installations, turnkey projects and critical everyday sewage needs. Partner with us to optimize system performance for your unique operational conditions and lower lifecycle costs.