Rail Road
Products - Air Dryers

  • Designed for locomotive use
  • Non volatile memory system
  • Automatic Purge control valve
  • Fixed Volume Automatic Drain valve


Moist Air from the compressor enters into the Pre filter through the top manifold. Water and oil coalesces here. The condensate with water and oil is drained by the Drain valve. The drain valve is periodically opened by the controller. The specially designed drain valve discharges only a fixed volume of condensate and minimizes air loss. The air then passes through the Inlet Shuttle valve and the Drying tower. In the drying tower, Activated Alumina adsorbs the water vapour present in the air and sends out Dry air of required Dew point. Fine Alumina powder which may come from the bed of desiccant is removed by the After filter. Clean and dry compressed air is let out through the outlet shuttle valve and Purge Control valve.

The Purge Control Valve Diaphragm senses the outlet flow and accordingly the Purge Air port size area is varied. This varies the amount of Purge Air during regeneration in proportion to the flow of compressed air through the dryer. It is also a function of the inlet pressure and hence only uses purge air in proportion to the moisture load.

The two towers operate alternately in the drying and regeneration phases. In the regeneration phase dry purge air is passed through the tower under regeneration and released into the atmosphere. Under given operating conditions (service pressure of 10.5 Kg/cm2 (g)) 10% of the airflow is used for regeneration. A fixed quanity of air is purged during very low flows. The regeneration phase is shorter than the drying phase in order to allow the regenerated tower to return to service pressure before a new cycle starts. The purge is 10% for units with Auto Adjust purge control valve and fixed 15%without Auto Adjust purge control valve.


  • Designed for locomotive use : Meets all Environmental and functional specifications for the Railroad industry. This dryer will withstand the vibrations, temperature in a locomotive platform out side the locomotive.
  • Operates over a wide Voltage range.
  • Non volatile memory system - The dryer is completely switched off when the compressor is off and restarts where the cycle was stopped. This increases the life of the dryer.
  • Automatic Purge control valve : Adjusts purge air depending on the compressed air flow and pressure. This ensures guaranteed dew point at optimized purge loss. This also reduces compressor usage.
  • Fixed Volume Automatic Drain valve drains condensate without wasting much of compressed air. It has a fail safe design.
  • Optimised design to meet Input-output dewpoint depression requirement.
  • Desiccant health indicator for each desiccant tower.
  • Pre-filter health indicator.
  • Low MTTR
  • High MTBF
  • All aluminum construction for corrosion free long life.
  • Slide-In mount : The dryer can be slided in and out for service and installation in minutes, when installed in the mounting bracket (e.g. Trident MB1).
  • Small size
  • Dewpoint depression of 30oC at design airflow and 15oC at worst case of airflow and ambient temperature.
  • Low pressure drop of 3% of inlet pressure at design air flow.


Trident Locomotive dryers are designed exclusively for the railroad industry for the following applications :

  • Electric Locomotives
  • Diesel Locomotives
  • Commuter Locomotives
  • Shunting Locomotives
  • Mining applications