Search Research Equipment

Description

The Microfluidizer high shear fluid processor relies upon the forces of shear, impact, and occasionally cavitation to emulsify a liquid-liquid system or to deagglomerate and disperse a solid into a liquid. The process takes place at high energy intensity levels within an interaction chamber.

The FPE Microfluidiser is especially equipped for the application of emulsification. This by using an Y shaped interaction chamber (F12Y; minimum internal channel of 75μm) in combination with an APM (= Auxiliary Processing Module). The APM is always a "Z" type chamber with larger openings than the high shear chamber.

Technical Details

Principal

The Microfluidizer high shear fluid processor relies upon the forces of shear, impact, and occasionally cavitation to emulsify a liquid-liquid system or to deagglomerate and disperse a solid into a liquid. The process takes place at high energy intensity levels within an interaction chamber.

The FPE Microfluidiser is especially equipped for the application of emulsification. This by using an Y shaped interaction chamber (F12Y; minimum internal channel of 75μm) in combination with an APM (= Auxiliary Processing Module). The APM is always a “Z” type chamber with larger openings than the high shear chamber. See picture 2 and picture 3.

The APM placed inline, upstream the chamber is much like an in-line mixer or pre-processor to make a pre-emulsion and prepare the material for smaller passages of the chamber.

The APM placed inline, downstream the chamber is to add backpressure. This enhances the effectiveness and helps increase the life time of the chamber.

Chamber Wear

The chamber’s exterior is made of stainless steel and the interior is made of aluminum oxide ceramic (AOC). As chambers begin to wear, their flowrates will gradually increase, until they are unable to maintain maximum pressures.

Factors contributing to abnormal chamber wear:

• Air mixed in with the fluid (through cavitation) by: 

  • Improper priming of the pump

  • Entrained foam from the product

  • Air trapped inside the product

  • Allowing the product reservoir (hopper) to empty completely

• No APM downstream of a Y-chamber

• Processing of a very abrasive material

A measure of the chamber wear is an increased flowrate at a specific pressure on the machine. The table with measured flowrates pressure combinations are available at the Wiki page.

Process Controls

There are five process control variables to control/optimize:

•  Type of chamber
•  Size of the chamber

• Process pressure. The pressure is driving force for the shear and for the flowrate. Increasing the pressure will increase the shear rate and the flowrate.

• Number of cycles the material will pass through the processor. This processor is developed for batch style operations. A volume of sample can be processed in discrete passes through the chamber. Additional passes will increase the exposure time and can help to reach the desired size distribution

• The inlet/outlet temperatures (i.e. the thermal history). The pressure also raises the temperature of the sample. For every 1000 psi of  pressure applied to water, the temperature will rise by 1.0ºC - 1.7ºC.

   

  Pre-heating/cooling of the samples can assist in particle size reduction and in making emulsions. There is a cooling-coil heat exchanger that can return the sample back to ambient temperature before it exits the system.
  The material’s thermal history is very important to understand for each application. Many applications will respond differently based purely on the thermal history.

   

User Instructions.

The forces in the instrument are very high. Instructions must be followed carefully.

1. Chamber connections.

• Mounting/ dismounting of the chambers is only allowed by the equipment managers.

• The APM must be installed inline, downstream the F12Y high shear chamber. This way protecting the shear chamber.

• Both have a restricted flow direction. Always check if this is done correct.

• The connection screw In and Out the chambers fits really good. First mount them only with the fingers. The tool should only be used for the final touch.

   

1. AIR; The chambers are rather sensitive to air cavitation.

• Be sure to purge well, until all the air is removed from the system.

• During the process, monitor the Inlet tank well to prevent air go in the system.

1. Temperature control. For the temperature control the Microfluidiser Processor is equipped with a cooling coil heatexchanger placed in a metal beaker.

   • A first rough option to control the temperature is by closing the In and Outlet connection of the beaker and fill it with water of the desired temperature.

   • A better option would be the connection of a waterbath (or chiller) to the metal beaker. Doing this, the circulation capacity of the bath will be critical because the beaker is open at the top.

1. Processing Protocol.

1. During storage the system is filled with 2-Propanol. This must be replaced by MilliQ-water.

   • Unscrew the connection below the Inlet tank. Disconnect the tank, dry the tank and the rubber ring. Connect it again.

   • Put 500ml MQ-water in the Inlet tank.

   • Open the Purge valve four strokes and put the tube in a waste beaker (Figure 5).

   • Check if the red valve (figure 4) is closed. Open the Air supply at the wall.

   • Set the reducer valve to pressure of 40Psi.

   • Slowly Open the red valve until the 2-Propanol is gone. Now close the Red valve and close the Purge valve.

   • Fill the Inlet vessel again until 500ml with MQ-water. This is the total rinsing volume.

   • Open the Red valve again and collect rinsing fluid from the silicon tube connected to the cooling spiral.

   • When almost all water is gone, close the red valve.

      

2. Make a coarse emulsion, minimum volume is 100ml.

   Adapting the pressure must be done while the processor is pumping.

   • Unscrew the connection below the Inlet tank. Disconnect the tank, dry the tank and the rubber ring. Connect it again.

   • Put the coarse emulsion in the inlet tank.

   • Set the pressure with the reducer valve to the achieved shear pressure.

   • Slowly open the red valve. The first few ml is waste, due to the internal volume of the system.

   • Collect the produced emulsion. When the Inlet tank is almost empty close the red valve.

   • For small droplets with a narrow distribution at least 3 passes are necessary. For this, put the produced emulsion back in the inlet tank. Open the red valve again until almost everything is gone.

1. Cleaning Procedure

   After usage the Microfluidiser must be cleaned thoroughly according to following protocol:

   • Unscrew the connection below the Inlet tank. Disconnect the tank, clean and dry the tank and the rubber ring with hot tap water and paper. Connect it again.

   • Put 500ml hot water with soap in the Inlet tank.
     Use Inlet Pressure = 60Psi. Open the Red Valve and rinse the chambers until almost all the water is gone. Close the Red Valve

   • Continue the rinsing with at least 1000ml more MQ water.

   • After a series of experiments an additional rinsing step with 0.1M NaOH is necessary.

     • Now fill the Inlet tank with 100ml 0.1M NaOH.

     • Pump half of the volume through the chambers, close the Red Valve. Wait for 3 minutes.

     • Now almost empty the Inlet Tank and close the Red Valve.

   • Now directly rinse with an additional 1000ml of MQ-water.

2. Storage procedure

   • Unscrew the connection below the Inlet tank. Disconnect the tank and dry the tank and the rubber ring with hot tap water and paper. Connect it again.

   • Add 100ml 2-Propanol to the Inlet Tank. Rinse the chambers until the 2-Propanol comes out (10-12 strokes). Some must be left in the Inlet Tank.

   • Cover the Inlet Tank with Alu-foil.

3. Finishing

   • Close the main valve at the wall

   • Reduce the Set Pressure on the reducer valve to zero.