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Quotes - Engineering - SalesNon-Cycling Refrigerated Air Dryers, 1,600 to 4,200 SCFM
Central-plant dryers for 300 hp and larger compressors
Above 300 hp the compressor room is usually a plant in its own right: two or three screw machines on a sequencer, a large receiver, a header that runs the length of the building. The dryer here is sized for 1,600 to 4,200 SCFM of combined delivery, which is a single 350 to 900 hp screw or centrifugal compressor, or two 300 hp screws with a third on standby, at 100 psig and 100°F.
Non-cycling makes sense at this scale when the plant runs continuously, because the refrigeration compressor of a 2,500 SCFM dryer draws 15 kW whether it cycles or not, and the thermal-storage hardware that lets a cycling dryer rest is only paid back by idle hours. A continuous process plant has none, so it buys the simpler machine with hot-gas bypass control and a steady 38°F pressure dew point.
Nine current models cover the band. The direct-expansion line runs 1,600 to 4,200 SCFM in seven sizes on 4 in and 6 in ANSI flanges, and the large plant dryer adds 2,500 and 3,000 SCFM units with 6 in flanges, networked controls and two-stage separation. All are 460 V three phase; 575 V is available on the direct-expansion sizes.
- Rated 1,600 to 4,200 SCFM at 100 psig, 100°F inlet and 100°F ambient
- 4 in flanges to 2,400 SCFM, 6 in flanges from 2,500 SCFM; 460/3/60 power
- 7.8 to 19.6 kW absorbed; 575 V option on the direct-expansion sizes
- Zero-air-loss demand drains and digital or networked controls on every model
Every 1,600 to 4,200 SCFM non-cycling model
Nine flanged models rated at 100 psig, 100°F inlet and 100°F ambient, listed with connection size and supply voltage. Each part number links to its specification page with dimensions and weight.
| PART NUMBER | SERIES | SCFM | CONNECTION | VOLTAGE | STATUS |
| DXR 1600 NA | DXR Series | 1,600 | 4 in ANSI flange | 460/3/60 (575/3/60 optional) | Current |
| DXR 1800 NA | DXR Series | 1,800 | 4 in ANSI flange | 460/3/60 (575/3/60 optional) | Current |
| DXR 2200 NA | DXR Series | 2,200 | 4 in ANSI flange | 460/3/60 (575/3/60 optional) | Current |
| DXR 2400 NA | DXR Series | 2,400 | 4 in ANSI flange | 460/3/60 (575/3/60 optional) | Current |
| DXR 3000 NA | DXR Series | 3,000 | 6 in ANSI flange | 460/3/60 (575/3/60 optional) | Current |
| DXR 3500 NA | DXR Series | 3,500 | 6 in ANSI flange | 460/3/60 (575/3/60 optional) | Current |
| DXR 4200 NA | DXR Series | 4,200 | 6 in ANSI flange | 460/3/60 (575/3/60 optional) | Current |
| HPRP2500 | HPRplus Series | 2,500 | 6 in flange | 460/3/60 | Current |
| HPRP3000 | HPRplus Series | 3,000 | 6 in flange | 460/3/60 | Current |
The two series in this band
Sizing a multi-compressor plant
Add the delivery of every compressor the sequencer can run at once, not the installed total. A plant with three 300 hp screws and one on standby is a 2,600 to 2,800 SCFM duty, which lands on the 3,000 SCFM dryer with margin for a 105°F inlet; if all four run in summer peaks it is the 3,500. Centrifugal compressors are sized from their data sheet rather than from horsepower, because their delivery moves with inlet air temperature and the surge margin. Where the plant expects to add a compressor within the dryer's life, buy the next size now; a 4,200 SCFM dryer costs far less than two 2,200s piped in parallel.
Pressure drop counts at this flow
At 3,000 SCFM every psi lost across the dryer and its filters is roughly half a percent of the compressor plant's energy, so a dryer with 3 psi of loss instead of 5 pays for itself on the electricity bill. The current exchangers are designed for low air velocity, and the flanged connections should match the header rather than be reduced to save on fittings. Keep the 1 micron prefilter and the 0.01 micron afterfilter sized for the full plant flow, and change elements on differential pressure, not on the calendar.
What sets the two series apart
The direct-expansion line is the straightforward choice: one aluminum precooler, chiller and separator block, hot-gas bypass, a zero-air-loss drain and a digital dew point display, in seven sizes from 1,600 to 4,200 SCFM. The large plant dryer at 2,500 and 3,000 SCFM adds stainless brazed-plate exchangers, a two-stage separator that removes particles of 3 micron and larger, level-actuated demand drains and a controller with Ethernet and RS485 ports so the dryer reports into the plant system. Both hold the same dew point; the second is for plants that want the dryer on the network and the five-year warranty option.
Cooling, room and installation
Every model in the band is air-cooled and rejects tens of kilowatts of heat into the compressor room, which is one more reason the room needs ducted exhaust. The 3,000 to 4,200 SCFM units stand about 78 in tall and weigh close to a ton, so they are set on a pad with the flanges at header height and a full-flow bypass loop around them. For a plant that idles at weekends the large cycling and digital-scroll dryers are the alternative, and the multiple-compressor page covers sequencing and header layout.
Central-plant dryers above 300 hp, in practice
On a level pad sized to the cabinet, with spool pieces bringing the flanges to header height rather than blocks stacked under the dryer. The 3,000 to 4,200 SCFM units weigh close to a ton, so the header needs its own supports on both sides; pipe left hanging on the dryer's flanges strains the exchanger connections, and leaks follow within a season. Leave room to pull the panels, and route the drain lines clear of forklift traffic.
On differential pressure, never on the calendar. At 3,000 SCFM each psi lost across the dryer and its filters adds about half a percent to what the compressors spend on electricity, so an element that has loaded several psi above its clean reading wastes more than a new one costs. Fit differential gauges or transmitters on both housings, record the clean figure at start-up, and set a change point the shift walk can check.
On a single central header, yes. A failed refrigeration circuit on a dryer of this size can send wet air to the whole building before anyone reads the panel. The 2,500 and 3,000 SCFM plant dryer has a dry-alarm contact that can go straight to the plant control system. On the direct-expansion sizes, add a fixed dew point sensor downstream and wire it to an alarm the maintenance team will actually see.
