F 425 Flux Barrel Pump – 99.9% Drum Emptying

Pump type:

• F 425 centrifugal barrel pump with ceramic-oxide mechanical seal
• Ex-classification: Ex II 1/2 G c IIB T4 (stainless steel and Hastelloy C versions only)
• Outer tube material: Polypropylene (PP), Stainless Steel 316 Ti or Hastelloy C 
• Driveshaft: Hastelloy C, Stainless Steel 316
• Inner tube: Steel-cored polypropylene, Stainless Steel 316 Ti or Hastelloy C
• Impeller: ETFE axial impeller, optional semi-axial (Z) impeller
• O-rings: FKM (optional FFKM, EPDM available – please contact us)
• Immersion lengths: 1000 mm (for 200 l barrels), 1200 mm (for 1,000 l IBCs) (700 mm for smaller containers available upon request)
• Outer tube diameter: 40 mm – 50 mm depending on material and configuration
• Outlet connection: G 1 1/4” A BSPP
• Suitable for use with F 414, F 416 Ex , FEM 4070, F 457, F 458, F 460 Ex and FBM 4000 Ex motors
• Please note that a hose connection is not included and must be purchased separately.

• Max flow rate: Approx. 120 L/min*1
• Max discharge pressure: Approx. 26 mwc*1
• Maximum liquid temperature: 50 degrees C (PP version) 100 degrees C (stainless steel version) 120 degrees C (Hastelloy C version) 
• Max density: Approx. 1.8 g/cm³
• Max viscosity: Approx. 1,000 mPas
• Dry run limitations: Not suitable for sustained dry-running
• Solids handling:  Not recommended for handling large quantities of solid particles (see pump model F 430)

*Measured with water at 20 degrees C in open flow condition. The maximum figures listed above are dependent on the application, fluid properties and the pump configuration. Please refer to technical data sheets or performance diagrams.

*Dependent on pump type, diameter and motor.

Please see our comprehensive list of media examples suitable for the F 425, based on pump material, here.

High-value liquids

Engineers and process technicians handling high value, or hazardous chemicals require efficient, safe pumps. In addition, the elimination of unnecessary waste and potentially dangerous spills is a top priority. The Flux F 425 barrel pump is uniquely designed for this purpose.

Furthermore, its flowback stop valve can be activated while the pump is still running. Therefore, retaining liquid inside the pump body and discharge hose, and consequently eliminating drain-back.

In addition, compared to standard centrifugal barrel pumps, which can leave several litres of residual liquid in the container, the F 425 cuts waste by over 95%. This translates into cost savings, not only through a reduction in waste, but also through lower barrel cleaning costs and time lost to spill clean-up. 

Finally, the ability to retain liquid inside the pump reduces operator exposure to potentially hazardous media.

Combine with our FES fume gland when handling dangerous or toxic liquids

Plus, when handling dangerous or toxic liquids, the F 425 barrel pump can be used in conjunction with our FES fume gland.

This reduces emissions of hazardous vapours and further reduces safety risks for the operator. 

We recommend the F 425 for:

• Hazardous area use and handling dangerous, highly flammable, or highly toxic liquids  (ATEX-rated Stainless Steel 316 and Hastelloy C versions available)
• Chemical dosing and precision batch dispensing
• Handling high value products, such as cosmetic fragrance oils and perfumes
• Operations requiring strict vapour or contamination control
• Heavy-duty use in industrial barrel emptying applications

F 425 can be powered by any F 400 series drive motor, however, pumps used in Ex applications require an Ex-approved motor.

The Flux F 425 is unequivocally the optimal solution for industry professionals aiming to maximise yield, while minimising waste. As a result of its positive-action backflow stop valve, the F 425 achieves almost complete fluid evacuation from a standard 205-litre barrel. Consequently, leaving behind as little as 0.2 litres**.

Handling high-value, highly flammable or toxic substances demands exceptional performance because every millilitre matters. This precision protects both budgets and the environment.

Manual backflow prevention

The pump’s manual backflow prevention valve enables the user to close pump inlet while the motor is still running. This design stops residual liquid draining back when you shut down the motor. It reduces product loss and lowers the chance of a spill when you remove the pump from the barrel.

Therefore, the F 425 pump protects the operator and the surrounding environment while reducing barrel cleaning costs.

This makes the F 425 the go-to choice for manufacturers handling products such as pharmaceutical precursors, isocyanates, flammable solvents, high-value additives, or cosmetic fragrances.

These operations prioritise waste reduction and enhance operator protection to meet regulatory compliance and maintain workplace safety.

By significantly reducing the residual volume in every barrel, the F 425 supports sustainability, LEAN manufacturing, good laboratory practice (GLP) and cost-saving initiatives.

**assumes the drum is tilted

Flux F 425 and F 426 pumps are impeller driven centrifugal pumps for use with low-medium viscosity liquids. They look similar, share a similar structural design and are available in the same material options. However, they differ fundamentally in functionality and intended purpose.

F 425

The F 425 incorporates a manual shut-off valve at the pump inlet, below the impeller. The operator opens and closes the valve using the lockable handles at the top of the pump tube.

This unique feature allows the operator to close the pump inlet before withdrawing the pump from a barrel or IBC. By doing so, it prevents siphoning, backflow and spills, ensuring full control over liquid transfer processes, while addressing health and safety concerns.

Back-flow elimination is particularly useful when handling expensive, hazardous, or environmentally sensitive materials.

F 426

In contrast, the F 426 is known as a mixing pump. The user can switch the pump between pumping, mixing and combined pump / mix modes, by moving the lockable adjustment lever at the top of the pump tube.

The operating lever opens and closes two pairs of re-circulation ports cut in the side of the pump tube. This re-directs liquid flow between the side discharge port and the mixing ports.

Therefore, users can mix low-viscosity fluids and powder/liquid blends in barrels and IBC containers, then switch to pumping mode to transfer the finished product. Users can also mix flammable liquids with the stainless steel F 426 S model, provided the liquid has a conductivity of less than 10,000 ps/m.

In summary

• The same range of F 400 series drive motors powers both the F 425 and F 426 pumps.
• Choose the F 425 for maximum possible fluid recovery, reduced risk when handling environmentally sensitive media, or enhanced safety when transferring toxic or volatile chemicals.
• Opt for the F 426 if you require a barrel pump with selectable mixing function – a cost-effective solution for mixing and pumping, using only one piece of equipment.