
How Regenerative Dryers Work
The Drying Process
- Pre filtered air enters the dryer and is channeled through the desiccant tower/s.
- Wet air passes through the tower/s where desiccant draws water vapor in while under pressure.
- After flowing through the desiccant, the now dry air is sent downstream.
- After two minutes, the control timer sends out a pilot signal shifting the internal piston. When the piston shifts, air is redirected from this tower/s to the opposite.
The Regeneration Process
- A small amount of air from the dry outlet on the opposite tower/s percolates up through the regeneration orifice and back through the desiccant filled tower/s.
- The desiccant is dried as the sweep air passes back through the media.
- With the use of this air, the tower/s discharge water vapor through the mufflers located below the dryer manifolds.
- After 2 minutes, the control timer sends out a pilot signal shifting the internal piston. When the piston shifts flow is reversed and this tower/s begins drying the air.


Service: Piston & Bore Lubrication
Depressurize the unit prior to any element change or service.
Each piston and bore (2) follows the same maintenance routine.

- Disconnect tubing from Quick-Connect Fitting located on the piston cover. Push in on brass ring. While holding ring in, pull out tubing.
- Remove the four Socket Head Cap Screws holding the piston cover in place (4mm Hex Key Wrench).
- Remove Piston Cover for access to piston.
- Using a finger or a ½-13 bolt, remove the Piston from the Piston Bore; be sure you remove the Piston Spring.
- Using the provided grease, lubricate the Piston Bore. Grease thoroughly.
- Lubricate the three Piston O-rings shown above. Grease thoroughly. Note: It is unnecessary to grease the bottom Piston O-ring.
- Re-install the Piston and Piston Spring.
- Reattach the Piston Cover using the four Piston Socket Head Screws. Torque to 75 in lb.
- Reconnect pilot line.

Service Parts

Description | Part Number | |
A | Pre-filter with 5 micron element | C-FS34 |
B | Replacement Pre-filter Element | C-F7 |
C | Coalescing Filter with .01 micron Element | C-CF34 |
D | Replacement Coalescing Element | C-F7607 |
E | Tower Replacement ea. (RDD50 2 required) (RDD100 4 required) Change @ 4,000 hrs. | RDDT2 |
F | Piston Rebuild Kit ea. (RDD50 2 required) (RDD100 4 required) | RDDRKS |
G | Muffler Assembly (RDD50 2 required) (RDD100 4 required) | RDDM |
H | Regenerative Desiccant Dryer Timer & Control Block – 115 volt | RDDT115 |