Selecting a Flux Barrel Pump: A Detailed Guide

Choosing the right barrel pump is critical to ensuring safe, efficient liquid transfer. Each application requires careful consideration in order to select the most suitable pump. You will need to consider factors such as liquid type, viscosity, flammability, chemical compatibility and duty cycle. There are multiple pump designs, sizes, materials and motor options available. Therefore, selecting the most suitable configuration can significantly improve performance, reduce downtime and extend equipment life. And most importantly, careful pump selection will help ensure operators can safely transfer hazardous chemicals from barrels.

This detailed guide explains how to select a Flux barrel pump based on liquid characteristics, operating environment and process requirements. Whether you’re handling low-viscosity solvents, corrosive chemicals, or high-viscosity media, this article will help you identify the correct pump for your application with insight drawn from decades of Flux engineering expertise.

Barrel pumps are typically inserted vertically into a drum or container. They comprise a fixed pump tube, sometimes referred to as a lance, wand or stick. The pumping mechanism (typically an impeller or rotor) is positioned at the end of the pump tube and is thus fully immersed in the fluid. Therefore, fluid will flow into the pump inlet under the effect of atmospheric pressure and gravity. 

The most common barrel pumps are centrifugal designs. These pumps utilise a shaft mounted impeller, driven at high rotational speed by an electric or compressed air powered motor. The impeller energises the liquid and forces it upwards, in a direction parallel to the driveshaft, before the liquid is discharged from a side outlet port at the top of the pump tube.

Liquid viscosity and density

Two primary considerations when selecting a centrifugal barrel pump are the viscosity and density of the media. Handling higher viscosity and density fluids will have a similar detrimental effect on pump efficiency, discharge flow rate and discharge pressure. In simple terms, larger diameter, more powerful centrifugal pumps are required for handling such liquids. However, there are limits. Please continue reading to find out how to select the right Flux pump.

Flux barrel pump selection

Firstly, decide if the F 300 or F 400 series Flux barrel pump is most suitable:

F 300 Series pumps

F 300 pumps are simple, portable, lightweight transfer pumps fitted with either an electric motor or cordless battery-powered motor.  These pumps are suitable for intermittent or continuous operation with fluids up to 250 mPas and density (S.G.) 1.3. However, they can be used with certain higher viscosity and / or higher density fluids for short periods, with the caveat that flow rate will reduce due to the extra load applied to the pump and motor. These pumps are commonly used for emptying smaller 25 – 50 litre containers, when run times are naturally limited anyway. If using the FBM-3100 battery motor, note that battery life will be negatively impacted by pumping higher viscosity or higher density liquids.

F 400 Series barrel pumps

F 400 pumps are available in several types. With the exception of the F 426 mixing pump and F 425 99.9% emptying pump, F 400 series models are capable of handling fluids up to 1,200 mPas and max density (S.G.)1.9. They may be able to handle higher viscosity fluids for short periods, depending on the media rheology. Again, flow rate and delivery pressure are negatively impacted when pumping high viscosity and / or high density media. To compensate, select F 457 or F 416 high power motors. Please consult F 400 series web pages for further advice on selection of the correct F 400 series pump for your application.

F 570 and F 580 Series Viscopower pumps

Viscopower pumps are designed for handling a wide range of highly viscous media of various rheology types, including adhesive, Newtonian and Thixotropic (shear-thinning, or shear-sensitive) media. These pumps are available in vertical and horizontal designs, for insertion directly into a container, or connection to a low-level tank outlet valve.

F 570 Series pumps are available with a choice of two gearboxes:

• Standard i16 double-stage gearbox – media to up to approx. 30,000 mPas may be pumped.
• Optional i7 single-stage gearbox – the pump can handle media up to approx. 80,000 mPas.

F 580 series pumps with bearing flange can handle media up to approx. 100,000 mPas.

Note that in all cases, viscosity capability may be reduced if pumping highly adhesive, dilatant or Newtonian media, eg. honey or glue. Likewise, viscosity capability may be increased when pumping shear sensitive, cohesive media, eg. tomato paste, petroleum jelly.

Flux barrel pump duty cycle and run times

F 300 series impeller pumps are best suited to applications requiring intermittent use, for example, emptying smaller containers. Pump tubes are available in shorter 500 and 700 mm lengths for this purpose. Additionally, 1000 and 1200 mm long pump tubes are available for use in 200-220 litre barrels and IBC containers.  Despite their compact size, F 300 series motors are still suitable for sustained running. As such, they can be run for long periods without risk of overload. F 300 pumps and motors are also serviceable and repairable, with a wide stock of spare parts available locally for immediate delivery.

F 400 series impeller pumps are better suited to regular, heavy-duty, or even continuous use. The pump tubes are larger in diameter compared to F 300, thus, the pumps are physically stronger and can handle rougher handling. All F 400 series motors are S1 rated, therefore suitable for unlimited running. However, to reduce maintenance requirements consider FBM 4000 brush-less motors for continuous duty, very tough applications.

Flow rate & discharge pressure

F 300 series pumps can deliver max. flow rates of 40 – 65 LPM depending on the model. The max discharge pressure is approx. 0.8 Bar (8 m water column). F 400 pumps can deliver much higher performance – with flow rates up to 220 LPM and discharge pressure up to 3.2 Bar (32 m water column). Again this is model dependent.

F 500 Viscopower pumps can deliver up to 70 LPM, but delivery pressure increases to 15 Bar (150 m water column). This is because high pressure is required to overcome the friction losses created by moving sticky, viscous media in smaller bore pipework. Please consult our sales team, technical datasheets and pump specific performance curves for more information.

How to read pump performance curves

Every Flux barrel pump has a defined performance range, which is shown graphically on a performance curve. The curves compare discharge pressure (on the y-axis) against flow rate (on the x-axis). It’s vital to check the curves to ensure your preferred pump can meet desired flow rate and discharge pressure. To create the performance curves, hydraulic testing is carried out with water under controlled conditions. Flow rate is measured at specific discharge pressures and the information is plotted on a chart, thereby creating a curve (or line).

It’s important to keep in mind that all pump performance curves result from testing with water. The performance curves will shift downwards and to the left, when pumping higher density and higher viscosity fluids. Performance can be reduced dramatically, up to the point when the pump can no longer create any flow.

Some performance curves also include the effect of motor power, measured in watts (W) or kilowatts (kW), on performance. In simple terms, more powerful motors will deliver more flow and / or discharge pressure. In the case of compressed air powered pumps, air inlet pressure will be shown instead. Air consumption may also be shown. This is useful to understand how much compressed air is required at any specific point on the performance curve. In turn, this indicates the size of the compressor required.

Note that performance curves are also measured with the pump running in an open flow condition. This means the performance shown on the curve does not take into account pressure losses (friction loss) created in any discharge hose or pipework. Imagine the flow rate is measured with water simply pouring out of the pump discharge port.

Calculating flow rate using a pump performance curve

In order to calculate actual flow rate in a pump system, the vertical pumping head (vertical distance over which the liquid must travel) and the pipework pressure losses must be considered. Friction losses are increased by any bends, static mixers and valves in the discharge pipe. Plus, pipe bore size and overall pipe length will impact friction losses. In addition, friction losses are increased considerably when pumping viscous media, especially adhesive media.

Use an online pressure loss calculator to calculate the losses in the pipework system. Adding the system friction loss together with the vertical head gives a figure for total discharge head. This is the pressure shown on the y-axis of the performance curve.

All performance tests are conducted with liquid flowing to the pump inlet under the natural effects of gravity and atmospheric pressure. In the case of self-priming pumps e.g. air-operated diaphragm pumps, suction head is therefore not considered when measuring pump performance. Static suction head is the vertical distance from the pump inlet to the liquid level, when the pump is mounted above the liquid level.

Motor options and environmental considerations

Depending on pump type and size, Flux barrel pumps can be powered by battery, electric or compressed air motors of various sizes. Let’s take a look at the options in more detail:

F 300 motor options

F 300 series pumps can be powered by an electric commutator motor, or a cordless motor with 18 V Li-Ion battery. The battery motor is a totally enclosed, double-walled design, with IP 44 ingress protection. This means it can be used in tough environments containing steam, or aggressive / corrosive fumes. The battery motor is available with either 110 V or 230 V charger.

F 300 electric commutator motors are the smallest in our range, with 230 W power output. The motor is an internally cooled design with IP 24 ingress protection. Internal cooling means that cooling air is pulled through the motor windings, meaning these motors are not well suited to environments with corrosive fumes. Models are available for either 110 V or 230 V single-phase electricity supply.

F 400 motor options

There are several more motor options available for the F 400 series pump range. All F 400 series electric motors are available for either single-phase 230 V or 110V power supply. Certain F 458 and F 460 Ex models are suitable for 12 V or 24 V DC power.

Standard motors (models FEM 4070 and F 457) are IP 24 internally-cooled designs with single-walled Polyamide plastic housings. They are ideal for most common pumping, mixing and transfer application in safe areas. Cooling air is pulled through the motor internals by the fan, meaning these motors should not be used in explosive or corrosive atmospheres.

F 458 motors are available with either 460 W or 700 W power ratings. These motors are double-walled, externally cooled, hermetically sealed motors with IP 55 ingress protection. Cooling air is directed between the walls of the motor housing and not through the motor windings, therefore, they can be used in corrosive, humid or steamy environments. They are ideal for use in food and pharmaceutical applications. This is because the motor housing remains waterproof if subjected to an indirect pressurised water jet, as may be encountered in a food production area. Additionally, any carbon dust created by brush wear will be contained inside the motor housing, reducing any chance of media contamination.

F 460 Ex motors are very similar to the F 458 models. However, these motors are designed and tested for use in explosive atmospheres (ATEX approved and therefore marked with the red Ex symbol). They should be used with and F 400 Ex model pump tubes. The F 460 Ex motor is IP 55 ingress protected, but it is not hermetically sealed. F458 and F 460 Ex motors have identical, robust aluminium motor housings, with corrosion resistant paint. They can be ordered in bare aluminium (without paint), if project specifications demand a particular paint finish (applied by others). F 458 motors can be ordered with a clear lacquer finish, if desired.

Note Flux pumps and motors should not be left outdoors, or exposed to salt spray, rain or frost. This can cause corrosion and premature failure of bearings, gearboxes and motors. Additionally, IP 24 motors, pump tubes and gearboxes should not be subjected to high pressure water jetting.

Brushless ATEX motor options

For demanding ATEX applications, the FBM 4000 Ex brushless electric motor is recommended for its reliability in tough, heavy duty applications. This motor is constructed using the same IP 55 rated housing and sealing arrangement as the F 460 Ex model. However, the motor requires minimal maintenance as there are no carbon brushes that require replacement. FBM 4000 Ex has a power output of 600W and is suitable only for 230 V power supply.

Compressed air motor options

ATEX compressed air motor options are also available for F 400 and Viscopower series pumps. All Flux air motors are vane driven, rotary designs. Model F 416 Ex is suitable for use with all F 400 and F 570 model pumps. With a power output equivalent to 900 W, they are among the more powerful Flux motors. F 416 provides a significant benefit, in that an oil-lubricated air supply is not required. Therefore, these motors can be used in sanitary, food and pharmaceutical applications as exhaust air will not contaminate the local environment. Note however, the compressed air supply should be dried and filtered to prolong vane life and reduce risk of corrosion. Flux air motors are not suitable for use in wet environments.

F 500 motor options

F 580 Viscopower pumps with bearing flange are powered by a range of three-phase DSM induction motors and FPM compressed air motors. These pumps require motors with 90 L frame size and  B 14 B (or B 34 B) face flange. Maximum motor speed is 1000 RPM. Running these pumps any faster can result in shaft or bearing failure.

Note that 1000 RPM motors are readily available in the correct 90 L frame size. 750 RPM motors (required for slower flowing media) are unavailable in the correct size, thus they require modification to fit correctly. The motor will be frame size 100 and must be fitted with a B14 flange, instead of B14B. As 100 frame motors have a longer 28 mm shaft, a 10 mm extender plate is required to ensure the motor is mounted correctly. Otherwise, there may be contact between the motor shaft and the pump shaft. 

Many electric motor options are available, covering a range of power outputs (from 750 W to 2.2 kW) and motor speeds to suit specific applications. Higher power motors should be used for very viscous or adhesive media. Motor options include close-coupled start-stop switches, anti-condensation heaters, uprated seals and stainless steel housings for sanitary use.

Flux barrel pump chemical compatibility and temperature

To prevent material degradation and premature failure, consult the Flux chemical compatibility chart to ensure that all wetted parts are suitable for the specific chemicals you wish to pump. This includes materials of the pump body, impeller, driveshaft, bearings and o-rings.

The Flux chemical compatibility chart also lists the density (S.G. or specific gravity) of many common chemicals, so take the time to check this. Liquid temperature has an impact on material selection (and chemical resistance). Therefore, our chart details chemical resistance at several different temperatures.

Flux polypropylene drum and IBC pumps are approved for maximum liquid temperature 50 deg C. For PVDF and aluminium pumps the max. temperature is 80 deg C and for stainless steel pumps, the max. temperature is 100 deg C. For liquid temperatures up to 120 deg C, we offer pumps in Hastelloy C material, however, these pumps are made to order, due to limited demand and high material cost.

For high temperature applications requiring plastic pumps in PP or PVDF materials, we consider the F 430 design to be the best choice. This is because of distortion resistance provided by the unique steel-cored inner tube, which in turn, provides optimal support for the mechanical seal.

Temperature considerations should also extend to the ambient temperature of the operating environment. Consult our technical datasheets for further details.

Container type and opening size

Drums, containers and IBC’s have different sized openings, therefore, check that the pump chosen will fit into the container to be emptied. For this reason, we offer pumps in different diameters. F 300 series pumps are available in 25, 28 and 32 mm diameter. F 400 series pumps are available in 41, 43  and 50 mm diameter and Viscopower pumps are available in 51 and 53 mm diameter.

Common IBC containers are available with both a top-mounted screw cap and low-level outlet. Vertical pumps can be inserted through the IBC cap opening. Alternatively, our TR and Miniflux series pumps can be coupled directly to the low-level outlet valve.

You can find further information about container types in our blog post here.

Choosing the right immersion length

Vertical Flux barrel pumps are available in different lengths, as follows:

• 1200 mm: For 1000-litre IBCs
• 1000 mm: For standard 205 – 200 litre drums
• 700 mm or 500 mm: For smaller containers (e.g., carboys, 25 litre drums)
• Longer and shorter immersion tubes are available for special applications. The shortest pump we manufacture is 200 mm and the longest is 3,000 mm.

Longer pumps can be used in smaller containers, if required. However, bear in mind that as liquid is removed from the container, the container will become less stable. As the motor is mounted at the top of the pump tube, the assembly is top-heavy and is therefore easy to knock over, potentially spilling the contents. This scenario can be avoided by using a pump stand, spring balance, chain, or hoist to support the pump.

Special considerations when selecting a Flux barrel pump

• High flow applications: Use F 400 series pumps with standard axial impellers and high power motors.
• High pressure applications: Select Viscopower progressive cavity pumps, or F 400 series pumps with high power motors and semi-axial “Z” impellers. For delivery pressures up to 2.4 Bar, consider models with 43 Z or 45 Z impellers. For IBC containers, consider our F 430 PP 100 / 50 high pressure pump.

• Flammable liquids: Stainless steel F 400 or Viscopower pumps with ATEX (Ex) approval are required for handling flammable liquids with flashpoints below 50 deg C. Likewise, only Ex-approved motors must be used.
• Handling one liquid only / similar liquids: Use F 314 or FP 424 seal-less pumps, offering reduced maintenance requirements.
• Handling multiple liquids: Consider F 310 or F 430 series pumps with mechanical seal. These pumps have minimal wetted area to prevent cross-contamination.
• Crystallising or solids-entrained liquids: Use F 310 or F 430 series pumps as their bearings are protected by the mechanical seal. Specify soft NBR or FKM stators for Viscopower pumps (if chemically compatible).
• Minimising waste and spillage: Choose F 425 pumps with foot valve. These pumps are capable of emptying 99.9% of the container contents.
• Mixing and pumping: Consider the F 426 switchable mixer pump as a cost-effective alternative to a separate mixer and pump.
• Hygienic applications: Use the F 427 pump for food and pharmaceutical applications, or F430 FOOD Ex pump for alcohols and foodstuffs containing particles.
• IBC and tank emptying: Consider the options: a vertical pump installed through the IBC cap, a self-priming diaphragm pump with suction tube, or a MiniFlux (or TR series) pump connected to the low-level outlet valve. Consult Flux UK for advice on baseplate or trolley mounted solutions.

Flux barrel pump accessories

We provide a complete range of accessories for most barrel pumps and IBC pumping applications. Accessories can be separated into the following groups:

Manual handling and operator safety

Barrel pumps are portable, therefore, manual handling requires consideration – operator safety should be a high priority for any business. This is particularly relevant for vertical IBC pumps, which are longer and more cumbersome than shorter pumps. Flux offers the following accessories to improve, or eliminate, potential risks associated with manual handling and storage:

• Wall mount storage brackets – firmly secures your pump in a safe location when not in use, reducing the possibility of accidental damage.

• Pump stands – Use when emptying open-head drums, tanks and mixing vessels. The stainless steel floor-mounted stand secures your pump using adjustable clamping jaws. Available with our without castors and in two different heights depending on the container size. Suitable for all Flux drum pumps, however, please check container height compatibility before ordering.

• Spring balancers – An adjustable, ceiling mounted hoist that takes the weight of the pump during container changes. This reduces physical strain on the operator and considerably reduces manual handling.  Spring balancers are particularly useful when using F 500 series progressive cavity IBC pumps fitted with heavier compressed air, or 3-phase induction motors.
• Container clamps – For use when pumping from open tanks, or mixing vessels. The container clamp secures the pump to the side of the container, ensuring it cannot slip when in use.
• Quick action coupling – Quick-release fitting for fast motor removal. A great way to reduce weight and manual handling requirements associated with vertical drum and IBC pumps. Suitable for F 400 series pumps only. 
• Compression glands and IBC caps – Compression glands are used to secure vertical pumps in drum bung holes or IBC caps. They help reduce vibration and the possibility of knocking over a drum that is nearly empty. Also reduce the risk of debris entering the container.
• Fume glands for emission control – Fume glands eliminate emissions of harmful, potentially flammable, vapours from drums and IBC’s, reducing health and safety risk for the operator and colleagues working nearby.

Dispensing accessories

In addition to pumps and motors, we can supply a wide range of items to create a manual or semi-automatic dispensing system:

• Flowmeters – Flux manufactures a range of flowmeters for use with our drum and container pumps. Batch controllers and connecting cables can be added to create a programmable, single-point dispensing system.

• Hoses, hose connections and fittings –  We offer hoses for safely transferring most liquids, including flammable products. Hose connections and adaptors of all types are also available. Contact us for more details.

• Spouts, hand nozzles and valves – These items are available in different materials, for safe manually-controlled dispensing of most common liquids. Non-return valves can prevent drips, or be used to control back-flow of liquid into the supply container. Contact us to discuss your exact requirements.

Are you ready to select your Flux barrel pump?

Selecting the right barrel pump ensures safe, efficient and reliable liquid transfer in your application. By considering factors such as liquid viscosity, chemical compatibility, duty cycle and motor type, you can choose a pump that maximises performance and minimises maintenance.

For application specific advice, we encourage you to email us or use the contact form at the bottom of this page to speak directly with our experts. You can also download our Pump Selection Guide for detailed specifications and performance insights.

For real-world pump compatibility examples, visit our Media Examples page. You can explore how Flux barrel pumps perform in different industries or environments and discover the perfect solution for your liquid transfer needs.