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Modular Cross Flow Filtration

Four membrane module options

The Armfield FT18 MkII is a small pilot-scale cross flow filtration system designed to operate with a range of membrane module configurations.

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The Armfield FT18-MkII is a small pilot-scale cross-flow filtration system designed to operate with a range of membrane module configurations. It can operate with as little as 5-10 litres of material but still give data that is useful for process scale-up. It can be used over the full range of cross-flow filtration applications from microfiltration through to reverse osmosis. It is the perfect tool to use, following on from flat sheet membrane trials with the FT17, for further process development and scale-up.


  • Four membrane module options:
    · Ceramic
    · Spiral wound
    · Hollow fibre
    · Tubular
  • Capable of microfiltration, ultrafiltration, nanofiltration and revese osmosis operations
  • Maximum filtration pressure of 50 bar
  • Clean-in-place capability
  • Backpulsing option (suitable for certain modules)
  • Variable retentate flow rate in order to change filtration cross-flow velocity
  • Retentate electronic flowmeter measurement
  • Retentate and permeate back pressure valves
  • Pressure sensors on the retentate inlet and outlet of the filtration module and on the permeate line
  • Mass balance option for permeate flow rate measurement
  • All parameters are data logged


  • Ability to assess the important cross-flow filtration mdule types on a single system
  • Fully instrumented to allow the effect of process variables on filtration performance to be measured and logged
  • Assessment of the effect of backpulsing on extending the time between CIP steps
  • 5-10-litre processing volume enables development with minimal product
  • Simple cleaning and maintenance protocols


The system uses a high-pressure piston-recirculation pump to circulate product through the filter module of choice.

The triple-piston design combined with high-pressure flexibles minimises pressure pulsation. The operator can use their own feed vessel or this can be specified (FT18-20 option). The speed of the recirculation pump can be adjusted to suit the particular filtration module and the product. The retentate back-pressure valve enables pressures up to 50 bar to be achieved. Accidental system over-pressure is avoided by a bursting disc downstream of the recirculation pump.

There is a permeate back-pressure valve so that accurate transmembrane pressures (TMP) can be set. Pressure sensors are sited on the retentate side on the inlet and outlet of the filter module, as well as on the permeate side. Any temperature gain in the retentate through recirculation at high pressure is removed using a 316 stainless steel shell and tube heat exchanger, which has corrugated tubes for improved heat transfer.

Ceramic Filter Module (FT18-5)
Filter housing: 316 stainless steel
Filter length: 1.00m
N° of channels: 1
Channel internal diameter: 7mm
Membrane area: 0.022m2
Available membranes: MF: 110-800nm
UF: 3-10nm (2-20 kDa)
NF: 200-600 Da
Spiral wound filter module (FT18-6) 
Filter housing: 1812 (1.8” x 12”) 316 stainless steel sanitary housing
Generic module for use with female elements from different membrane manufacturers 
Membrane area depends on element (max: 0.45m2)
The module can be used for MF, UF, NF and RO operations 
Max operating pressure: 40 bar
Hollow fibre filter module (FT18-7)
Membrane housing: Polysulfone
Filter length: 0.46m
Fibre internal diameter: 1.1mm
Max operating pressure: 2.1-2.8 bar
Membrane area: 0.09m2
Available membranes: 5-500 kDa
Tubular Filter Module (FT18-8)
Filter housing: 316 stainless steel
Filter length: 2 x 0.3m
Membrane area: 0.024m2
Max operating pressure: 40 bar (recommended)
Available membranes: UF: 2-200 kDa
NF: 60-75% CaCl2 rejection
RO: 80-99% NaCl rejection
Vessel (FT18-20)

30-litre 316 stainless steel retentate vessel for recirculated product, complete with sensor to protect against dry running. Mass balance option for permeate flow rate measurement.

Electronic Flow Meter (FT18-44)
  • Electronic flow meter that measures the recirculation (retentate) flow rate
  • Must be ordered with FT18-MkII base unit
Backpulsing/Backflushing (FT18-50)
  • This module enables filtration pressure to be reversed for a period of time during processing in order to reduce fouling and thus enable extended operation between cleaning cycles
  • This module is compatible with the Ceramic (FT18-5) and Hollow Fibre (FT18-7) filter modules only
  • Must be ordered with FT18-MkII base unit
System Control


  • As standard the system is controlled by a PC (not supplied) with a USB interface
  • An optional touchscreen system (FT18-60) can be used in place of a PC (not supplied)


Food: Dairy: Removal of microorganisms from milk and cheese brines, milk protein standardisation and concentration, whey demineralisation, whey protein fractionation, defatting of whey proteins, and filtration
Fermented foods: Clarification of wine, beer and vinegar, removal of alcohol from wine and beer, post-fermentation yeast recovery, wine lifting
Fruit juices: Clarification and concentration
Water: Water and waste water purification, desalination, water softening
Pharma: Concentration and purification of macromolecules, sterile filtration, viral clearance, cell separation, water purification
Edible oils: Degumming of vegetable oils

Technical Specification

Maximum flow rate: 1670 l/hr
Maximum operating pressure: 50 bar
Pressure sensors: 0-50 bar
Mass balance range: 0-6kg

Associated Equipment

  • FT140 Mixing Vessels
  • FT63/64 Laboratory Process Chiller


Electrical supply:
FT18-MkII-C: 380-415V 3ph 50Hz 10A
FT18-MkII-D: 208-220V 3ph 60Hz 20A
Water supply:
Towns water 10 l/min at 2 bar or equivalent flow recirculation chiller for lower temperatures
Air supply:
6 bar with minimal air consumption (required for FT18-50 option only)

Ordering Codes

FT18-MkII-C: 380-415V 3ph 50Hz 10A
FT18-MkII-D: 208-220V 3ph 60Hz 20A
Option ordering codes
FT18-5: Ceramic Filter Module (option)
FT18-6: Spiral Wound Filter Module (option)
FT18-7: Hollow Fibre Filter Module (option)
FT18-8: Tubular Filter Module (option)
FT18-20: Vessel (option)
FT18-44: Electronic Flow Meter (option)
FT18-50: Backpulsing/Backflushing (option)
FT18-60: Touchscreen system (option)

Overall dimensions

Length: 0.72m
Height: 1.50m
Width: 1.00m

Shipping specification

Volume: 1.9m3
Gross weight: 300kg