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What Plant Air Has to Do
A manufacturing plant runs one compressed air system for many jobs at once: impact wrenches and grinders on the floor, spindle purge and tool changers on the machining centers, assist air on a plasma or laser table, valve islands and grippers in the robot cells, and a blast cabinet in the corner. They share a header, so they share a dryer, and the dryer has to satisfy the fussiest of them. For almost every job on this floor that is a 38°F pressure dew point, ISO 8573-1 class 4, delivered by a refrigerated dryer sized to the compressor's full output in the compressor room's summer temperature. Laser assist air is the exception, and its page says so.
- One dryer at the compressor room, after the receiver, sized to the compressor: 65 to 250 SCFM for 15 to 50 hp, 300 to 1,250 SCFM for 60 to 250 hp
- 1 micron coalescing prefilter ahead of the dryer, 0.01 micron oil-removal afterfilter behind it, zero-loss drains at every low point
- Cycling dryers where demand swings with tools and cells; non-cycling where the compressor runs loaded across two or three shifts
Five Applications
Pick the Page for Your Line
Each detail page below opens with the air-using equipment on the line and what water and oil do to it, then gives the compressor size and flow behind it, the dew point and ISO class it needs, where the dryer and filters go, whether cycling or non-cycling suits the duty pattern, and a table of the series that fit. Most manufacturing duties land on the DXR and HPRB non-cycling series, the FLXA, TMC and NXC cycling series, and the GFN and NGF filter families, with the HHPR and APET high-pressure dryers where a booster feeds a laser.
One Dryer at the Compressor Room
The plant that grew one compressor at a time usually ends up with a dryer that was sized for the first one. The fix is not a dryer per department; it is one dryer downstream of the point where the compressors join, sized for their combined delivery, or one dryer per compressor where they sit in different rooms. Pipe it after the receiver so the bulk water has already dropped out and the flow is smoothed, put the 1 micron prefilter directly ahead of it and the 0.01 micron oil-removal filter directly behind it, and give it a bypass so an element change does not stop the plant.
Sizing is arithmetic, not guesswork. A 40 hp screw delivers 170 to 180 SCFM; in a 100°F compressor room that is the 185 to 200 SCFM dryer, and in a 110°F room the ambient factor of 0.88 pushes it to the 230 or 250 SCFM size. A compressor whose aftercooler has plugged with dust can deliver 120°F air and cut the dryer to 65 percent of its rating without anyone touching a setting, which is why inlet temperature is measured on the hottest afternoon before a dryer is blamed.
Series That Carry Manufacturing Duty
Shops to 50 SCFM: the HPRB non-cycling cabinet dryers and the smallest DXR sizes. Plants to 250 SCFM: the DXR non-cycling series where the compressor runs loaded all shift, the TMC and NXC cycling series where tools and cells make the load swing. Plants to 1,250 SCFM and beyond: the DXR sizes to 4,200 SCFM, the FLXA cycling series to 2,000 SCFM and the AES digital-scroll dryers to 10,000 SCFM. The cycling versus non-cycling page shows where the crossover falls.
Around the dryer: GFN and NGF prefilter and afterfilter pairs matched to every dryer size, HF housings for the larger plants, GF WS centrifugal separators ahead of the dryer on wet systems, ND zero-loss drains on the receiver, dryer and filter bowls, and the 1701 single-body bypass on dryers to 35 SCFM. A laser cell fed by a booster adds an HHPR or APET high-pressure dryer and a desiccant stage. All of it is on the refrigerated dryers and accessories pages.
Typical Range Across Manufacturing Applications
Starting points, not limits. Flow is the compressor's delivery at 100 to 125 psig; the dryer is corrected for inlet and ambient temperature before it is ordered.
| APPLICATION | TYPICAL COMPRESSOR | DELIVERED FLOW | DEW POINT NEEDED | DRYER BAND THAT FITS |
| Pneumatic tools & controls | 10–100 hp rotary screw | 40–450 SCFM | 38°F class 4; desiccant for outdoor control air | 20–250 cycling, 300–1,250 |
| CNC & machining | 15–75 hp rotary screw | 65–350 SCFM | 38°F class 4 | 65–250 SCFM |
| Laser & plasma cutting | 10–30 hp (plasma); 25–100 hp plus booster (laser) | 40–450 SCFM | Plasma 38°F class 4; laser assist –40°F class 2 desiccant after a refrigerated first stage | 65–250, high pressure |
| Robotics & automation | 15–75 hp rotary screw | 65–350 SCFM | 38°F class 4; class 3 oil for proportional valves | 20–250 cycling, 300–1,250 cycling |
| Blasting & surface prep | 50–250 hp rotary screw or portable | 175–1,250 SCFM | 38°F class 4; clean blotter test for oil and water | 300–1,250 SCFM |
Manufacturing plant air questions
Usually, yes. A 38°F dew point satisfies tools, machine tools, robots, plasma tables and blast cabinets alike, so one dryer at the compressor room sized for the total compressor output covers the floor. The exceptions are a fiber laser's assist air, which needs a desiccant stage, and control lines that leave the heated building.
For their combined delivery if both can run together, piped after the point where their discharges join and ideally after a common receiver. A 30 hp and a 50 hp screw together deliver about 350 SCFM, which is the 400 SCFM dryer in a normal room. If one compressor is a standby that never runs with the other, size for the larger one.
Non-cycling when the compressor is loaded 60 percent of the time or more, which is a two-shift plant with steady machine loads. Cycling when demand swings with tool use, when the plant idles nights and weekends with the compressor still up, or when a variable-speed compressor spends hours at partial flow. Above about 100 SCFM the energy difference pays for the cycling dryer in a few years.
Class 4 for water, which is the 38°F dew point of a refrigerated dryer, is the common specification for tools, machine tools and general pneumatics. Oil class 3 or better, from a 0.01 micron coalescing afterfilter, protects valve manifolds, proportional valves and any air that reaches a finished surface. Particle class follows the filters.
Because the air was dried and then re-cooled somewhere it should not have been: a header through an unheated roof space, a drop taken from the bottom of the pipe, or a dryer undersized for a hot compressor room on summer afternoons. Check the dryer outlet dew point at 3 pm in July, then walk the header.
