Components Overview: Variable Pressure Module (VPM)

The Variable Pressure Module (VPM) allows pressure to be applied to the system. Below is the overview of a VPM unit: 

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The VPM is configured to allow for two pressure stages allowing standard and low pressure operation:

  • Standard Pressure Range is 0 to 20 mbar. This is the typical mode of operation and is used for sizing and concentration measurements. 1 unit = 1 mbar (equivalent of 1 cm hydrostatic pressure).
  • Low Pressure Range is 0 to 2 mbar. This range is used for zeta potential measurements. 1 unit = 0.1 mbar


The pressure stage knob (C) adjusts from standard pressure to low pressure. Twist the knob clockwise while lifting to shift to the low pressure range. Ensure the system is disconnected from the instrument while changing the pressure stage.

VPM table

When inserting and removing the VPM nozzle from the fluid cell, rotate the nozzle slightly in a clockwise direction.