When handling delicate, viscous, or solids-laden fluids, pump selection becomes critical. The Liverani GR range of flexible impeller pumps are designed to address these challenges across industries including wine production, food processing, chemical handling, and pharmaceuticals.
What Are Flexible Impeller Pumps?
Liverani GR pumps are stainless steel, low-speed rotary pumps fitted with flexible impellers. As the impeller rotates inside the casing, its vanes deform slightly, creating a consistent movement of fluid from inlet to outlet.
This operating principle delivers a steady, pulseless flow without pressure spikes, making the pumps suitable for sensitive products that cannot tolerate shear or agitation.
Key Applications
These pumps are used across a wide range of industries due to their ability to handle both delicate and viscous fluids, including those containing suspended solids.
Oenological (Wine Industry)
- Wine transfer
- Must handling
- Stemmed grape processing
Food Processing
- Fruit pulp
- Honey
- Milk and yoghurt
- Liquid eggs
- Oils and tomatoes
- Brine
Chemical Applications
- Starch
- Water-based glues
- Paints and inks
Cosmetic and Pharmaceutical
- Liquid soaps
- Shampoos
- Moisturisers
- Cleaning products
They are also suitable for hygienic and sanitary environments where product integrity is essential.
Performance Capabilities
The GR range is designed to handle a broad spectrum of operating conditions:
- Flow rate: up to 690 litres per minute
- Pressure: up to 20 metres head
- Temperature: up to 100°C
- Viscosity: up to 50,000 cP
- Solids handling: up to 25 mm
- Connection sizes: 1” to 4”
These capabilities make the pumps suitable for both low-viscosity liquids and thick, heavy products.
Belt-Driven Design Advantages
The GR pumps use a belt-driven system rather than a gearbox. This provides several practical benefits:
- Allows operation at different speeds without complex gearing
- Protects the motor from overload by slipping under excessive load
- Reduces the risk of downtime and mechanical damage
- Offers a cost-effective solution compared to gearbox-driven systems
This is particularly useful when working with viscous or solids-heavy fluids.
Core Operating Benefits
1. Strong Self-Priming Capability
The pumps can self-prime up to 6 metres from dry. This allows:
- Emptying tanks, drums, and IBCs
- Operation without non-return valves
- No manual priming during installation
2. Reversible Operation
The pumps can run in both directions, enabling:
- Return of excess liquid
- Easy emptying of pipelines
- Simplified tank cleaning and refilling
3. Gentle Handling of Fluids
Low-speed operation allows transfer of:
- Fragile or shear-sensitive fluids
- Products with suspended solids
- High-viscosity liquids without emulsifying or damaging particles
4. Flexible Installation
The pump casing can be rotated into five different positions, allowing:
- Integration into existing pipework
- Greater installation flexibility without modifying systems
5. Smooth, Pulse-Free Flow
The design delivers a consistent flow rate, which is ideal for:
- Filling
- Dosing
- Filtration processes
Impeller Material Options
Different impeller materials are available depending on the application:
- Natural Rubber (NR): High mechanical resistance, suitable for water-based liquids
- Neoprene (CR): Balanced chemical and mechanical resistance
- Nitrile (NBR): Strong resistance to oils and fats
- EPDM: Suitable for hot fluids and CIP cleaning, resistant to acids and alkalis
- Silicon (VMQ): Suitable for high temperatures but with lower mechanical strength
All impellers are food grade, with EPDM and NBR available with FDA certification.
Construction and Materials
- Pump heads are supplied in stainless steel 304 as standard
- Stainless steel 316 is available on request
- Standard connections are Garolla, with alternatives available
- Multiple sealing and configuration options are available
This allows the pump to be configured for specific operational and hygiene requirements.
Control and Protection Features
The pumps can be supplied with control panels offering:
- On/off and reversing functionality
- Timer-controlled operation
- Integration with sensors (temperature, pressure, level)
- Dry-run protection via temperature monitoring
Dry-run protection stops the pump if internal temperature exceeds 50°C to prevent impeller damage.
Flow Control and Monitoring
Optional systems include programmable litre counters and flow meters, enabling:
- Real-time flow rate monitoring
- Batch control for filling applications
- Automatic stopping via signal output
- Integration into larger process systems
These systems can be supplied as standalone units or integrated with the pump.
Installation Options
The GR range is available in multiple configurations:
- Base-mounted units
- Trolley-mounted units for mobility
- With or without control panels
Weights vary depending on model:
- MINOR: approx. 36–46 kg
- MAJOR: approx. 42–53 kg
- MAXI: approx. 65–67 kg
Operational Considerations
Viscosity Impact
Pump performance is affected by fluid viscosity:
- Around 100 cP: approx. 25% capacity loss
- Around 4000 cP: approx. 60% capacity loss
Speed adjustments or variable speed drives are recommended for varying viscosities.
Speed Guidelines
- 100 cP: up to 900 rpm
- 2000 cP: up to 470 rpm
- 4000 cP: up to 300 rpm
System Design
- Pipe friction and suction lift must be added to total head calculations
- External relief systems may be required for certain models
- Direction of rotation must be checked during installation
Accessories and Customisation
Available accessories include:
- Stainless steel sanitary enclosures
- Control panels with reversing switches
- Hygienic inlet and outlet fittings
- Automatic barrel filling kits
- Sprinkler systems for cap management in winemaking
The pumps can also be customised with different impellers, seals, connections, and control systems.
The Liverani GR flexible impeller pump range is built for applications where fluid integrity matters. Its combination of gentle handling, self-priming capability, reversible operation, and flexible configuration makes it suitable for industries ranging from winemaking to food processing and chemicals.
With options for customisation, control integration, and handling of viscous or solids-laden fluids, it provides a practical and adaptable solution for a wide range of transfer and processing requirements.