Available as standard or Zero-Purge

Scope of Supply

  • Twin towers filled with silica gel desiccant
  • Elektronikon control panel with temperature and pressure sensors mounted on the dryer
  • Pre-filtration to 0.01micron / 0.01ppm (DD & PD or new combined UD+ twin element filtration)
  • After-filtration to 1 micron dust removal (DDp)
  • Pressure dewpoint sensor placed at dryer outlet
  • External heaters
  • Purge air blower
  • Interconnecting pipe-work with inlet and outlet connections
  • Mounted on a frame with forklift slots



  • -70ºC/-100ºF) molecular sieve desiccant
  • Pneumatic control kit
  • Drying towers insulation
  • Sonic nozzle to limit inlet air flow
  • Optimised purge nozzles for different inlet pressures
  • Zero Purge (ZP) Energy Saving variant

The working principle

The BD+ dryer consists of two towers containing silica gel desiccant. In one tower the silica gel beads adsorb the moisture from the air, when saturated the silica gel is reactivated. After half a cycle, the tower functions are reversed.


Adsorption drying phase

Wet compressed air enters the bottom of the drying tower via the inlet valve (1). The air flows upwards through the desiccant, which adsorbs the moisture. Dry air leaves the tower via the outlet valve (2).


Regeneration phase

When the desiccant is saturated, it has to be reactivated. A blower blows ambient air via the external heater (3), where the air is heated up. The heated air enters the tower and removes the moisture from of the desiccant. The now hot and wet air leaves the tower through the regeneration valve (4) until the heater is switched off by the thermostat (5) at the bottom. The reactivation phase is further improved by cooling the desiccant bed with a small bleed of dry, expanded compressed air (purge air) from the drying tower.

Zero Purge (ZP) option is available, offering the highest energy savings and lowest operating costs by eliminating the purge air requirement.


Tower Changeover

After regeneration, the tower is pressurised to the system pressure by closing the regeneration valve (4). The dryer is now ready to changeover over to the other tower. The tower changeover is controlled from the dewpoint sensor (6) in the outlet and the desiccant towers switch operation when the full capacity of the drying tower has been used, which is indicated by a degradation of outlet pressure dewpoint.



  • Compact, space-saving design with twin desiccant towers mounted on a frame with forklift slots
  • Oversized desiccant towers with typically a 30% desiccant overfill
  • Generously sized towers and piping to minimise pressure drop through the dryer
  • Stainless steel butterfly valves
  • Galvanised piping and flanged connections
  • 5 bar(e) maximum operating pressure


BD100-03Control and Monitoring

  • Display and control of the dryer with Elektronikon control system
  • Full colour graphical display
  • Internet-based visualization of your dryer is possible by using a simple Ethernet connection
  • Constant monitoring of dewpoint using a sensor placed at the dryer outlet; dewpoint is displayed on controller
  • Pressure dewpoint control to minimise purge air loss. Towers will only switch when desiccant is saturate.
  • Control panel protected to IP54
  • System warning and system fault alarms available from the control system
  • Dewpoint alarm


Features and Benefits

Feature Benefit
Generously sized desiccant towers Slow air speeds through dryer, maximising contact time between desiccant and air,   therefore enhancing drying performance
Pre and after filters mounted directly on the dryer Space saving and simplified installation
Self-cleaning shuttle valve and purge nozzle Maintenance free with reliable operation
Silencers with integrated safety valve Operation maintained in the event of a blockage
Units designed with lowest possible pressure drop Running costs minimised through lower energy consumption
Desiccant overfill of approximately 30% Maximises performance and reduces desiccant wear
Pressure dewpoint control with Elektronikon controller supplied as standard Ability to minimise purge air consumption and make full use of the drying capacity of the towers
Stainless 2 way valves Corrosion resistant and hard wearing