Flygt 3350 & 7121 Double Mechanical Seal Kit — Fits 7121.985, 3531.905

Flygt 3350 & 7121 Double Mechanical Seal Kit — Stainless Flange

Direct-fit replacement double mechanical seal assembly for Flygt 3350 and Flygt 7121 submersible pump applications, including the 7121.985 and 3531.905 builds. The assembly is supplied fully pre-assembled on a new stainless-steel flange, which simplifies installation, improves alignment and reduces setup errors during a rebuild. A complete O-ring kit is included.

At a glance

• Configuration: Double seal (upper and lower stage)

• Seal faces: TC/TC – TC/TC (Tungsten Carbide vs Tungsten Carbide, both stages)

• Elastomers: Viton (FKM)

• Mounting: Pre-assembled on stainless-steel flange

• Includes: Complete O-ring kit

• Fits: Flygt 3350, 7121, 7121.985, 3531.905

Applications

• Flygt 7121 — including 7121.985

• Flygt 3350

• Flygt 3531 — 3531.905

The Flygt 7121 is a large submersible axial-flow column pump built for moving high volumes at low head, used in flood control, stormwater, irrigation and raw water transfer, and fitting discharge columns up to 1400 mm with aluminum bronze or stainless steel propellers. The Flygt 3350 is a large-capacity submersible sewage pump used in municipal and industrial wastewater service. Both use the same double mechanical seal assembly covered by this kit.

Don’t see your exact build number? Call or text 561-414-1046 with your pump nameplate and we’ll confirm the correct configuration before you order.

Fitment note: Flygt seal assemblies can vary by build. Please enter your full pump model number at checkout under “Pump Model Number Notes” so we can confirm the correct configuration for your unit.

Why this kit:

Drop-in assembly. Because the seal arrives already mounted and aligned on its flange, you avoid the alignment errors that cause premature failure on a field-assembled double seal.

Hard TC/TC faces on both stages. Tungsten carbide against tungsten carbide gives excellent wear resistance in abrasive service and handles the heat generated at the higher surface speeds these large pumps run.

Viton (FKM) elastomers. Higher temperature capability and better chemical resistance than standard nitrile, which matters in industrial wastewater and where the pumped liquid carries aggressive chemistry.

Stainless flange. Strength and corrosion resistance, with precise seal seating.

Complete O-ring kit included. No separate add-on needed for a full rebuild.

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