KAESER DHS 4.0 Pressure Maintenance System – Ensuring Compressed Air Quality
Choosing the Right Pressure Maintenance System for Your Compressed Air Station
A pressure-maintaining system protects refrigeration dryers and filters from overflow during restart after periods of downtime. The KAESER DHS 4.0 series includes models with ball valves (threaded connections from G 3/4" to G 2 1/2") and with intermediate flanges (flanged connections DN 50 to DN 150)—each featuring patented pulse width modulation and a SIGMA NETWORK interface.
KAESER DHS 4.0 Pressure Maintenance System – Which model is right for your system?
After a shutdown, the compressed air system is depressurized. When the compressors are restarted, there is no resistance from system pressure—the compressed air flows through the treatment components at too high a velocity. A DHS 4.0 series pressure-maintaining system prevents this: It maintains the required minimum pressure until the system has reached operating pressure again.
DHS 4.0 with ball valve – threaded connection G 3/4" to G 2 1/2"
The G models are installed directly into piping with threaded connections. A high-pressure kit for operation up to 63 bar is available as an option.
| Model | Connection | Max. Overpressure | Dimensions (W × D × H) | Mass |
|---|---|---|---|---|
| DHS 4.0 20G | G 3/4" | 16 bar | 220×234×300 mm | 5.9 kg |
| DHS 4.0 25G | G 1" | 16 bar | 220 × 244 × 335 mm | 7.8 kg |
| DHS 4.0 32G | G 1 1/4" | 16 bar | 220 × 244 × 346 mm | 9.6 kg |
| DHS 4.0 40G | G 1 1/2" | 16 bar | 220×249×378 mm | 10.4 kg |
| DHS 4.0 50G | G 2" | 16 bar | 299 × 256 × 417 mm | 11.4 kg |
| DHS 4.0 65G | G 2 1/2" | 16 bar | 349 × 264 × 460 mm | 17.8 kg |
DHS 4.0 with intermediate flap – flange connection DN 50 to DN 150
The DN variants are installed directly into the piping using a flange connection and are suitable for larger nominal diameters.
| Model | Connection | Max. Overpressure | Dimensions (W × D × H) | Mass |
|---|---|---|---|---|
| DHS 4.0 50 | DN 50 | 16 bar | 220 × 244 × 427 mm | 9.6 kg |
| DHS 4.0 65 | DN 65 | 16 bar | 258 × 259 × 459 mm | 11.1 kg |
| DHS 4.0 80 | DN 80 | 16 bar | 258 × 268 × 489 mm | 12.6 kg |
| DHS 4.0 100 | DN 100 | 16 bar | 299 × 290 × 545 mm | 16.7 kg |
| DHS 4.0 125 | DN 125 | 16 bar | 348 × 320 × 597 mm | 23.7 kg |
| DHS 4.0 150 | DN 150 | 16 bar | 397 × 342 × 645 mm | 28.9 kg |
Ball valve or intermediate damper?
The selection depends on the existing piping: Piping with threaded connections (typically up to G 2 1/2") requires a model with a ball valve (G Series). For flanged connections starting at DN 50, the version with an intermediate butterfly valve is used. Both versions use the same spring-loaded pneumatic rotary actuator and the same electronic control unit—they differ only in the shut-off element and the connection type.
Integration into the compressed air station
The DHS 4.0 is installed between the compressor and the first treatment stage. This way, it protects Refrigeration Dryers, Compressed Air Filters and protects downstream equipment from uncontrolled overcurrent. The system can be integrated into the higher-level SIGMA AIR MANAGER 4.0 control system via the standard SIGMA NETWORK interface. For larger connection sizes starting at DN 200, we would be happy to provide you with personalized advice.
