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£1,400.56 – £1,512.03
*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.
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. Its flowback stop valve can be activated while the pump is still running, retaining liquid inside the pump body and discharge hose, thereby eliminating drain-back.
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. Furthermore, the ability to retain liquid inside the pump reduces operator exposure to potentially hazardous media.
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:
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, leaving behind as little as 0.2 litres**. This exceptional performance is particularly valuable when handling high-value, highly flammable or toxic substances, where every millilitre matters, both economically and environmentally.
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 the motor is shut down, thereby reducing product loss and the chance of a spill when the pump is removed from the barrel. Thus, 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.
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.
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.
The Flux F 425 barrel pump is vertical, axial (or optionally, semi-axial) rotor pump. The pump is driven by a detachable electric or compressed air powered motor, which runs at high speed (typically 3,000 – 10,000 RPM). The motor transfers drive to the pump through a replaceable coupling star in the head of the pump. The coupling star is a low-cost wear part than can be easily replaced, using a flat-bladed screwdriver.
The coupling connects to a threaded pump shaft, which is supported by a series of bearings. The bearings are contained within the inner tube of the pump. In the case of the F 425 pump, a ceramic-oxide mechanical seal seals the inner tube. The mechanical seal comprises two rings, one fixed in the inner tube, the other connected to the rotating impeller. The rotating ring is pressed against the stationary ring by a spring located behind the impeller. A thin film of the pumped liquid lubricates the seal faces, but liquid is unable to continuously pass through the seal.
The drive shaft turns a three-bladed impeller, imparting kinetic energy into the liquid as it flows into the pump inlet, under the influence of atmospheric pressure. Therefore, the pump cannot suck up the liquid; you must immerse it in the liquid to operate. The impeller effectively throws the liquid up between the inner and outer pump tubes in an axial direction, parallel to the inner tube and driveshaft.
In general, centrifugal barrel pumps with a mechanical seal such as F 425, should not be run dry for longer than 60 seconds, otherwise the seal can overheat and potentially fail. Therefore, Flux recommends that an operator is always present during operation.
F 425 is fitted with a manually-operated flowback stop valve, located just below the impeller. The stop valve is opened and closed using two handles, located at the top of the pump tube. The handles are fixed in place by a thumb-operated locking mechanism. Therefore, the operator can close the flow-back valve while the pump is running, preventing reverse-flow back into the barrel when the motor is switched off. This is particularly beneficial when the pump is being relocated, cleaned, or removed from hazardous environments. In addition, this pump can remove almost all of the barrel contents, thereby minimising waste and reducing cost – especially important when handling high-value products.
Compare Flux F 400 Series Drum Pumps
