1-805-484-2992
Quotes - Engineering - SalesRefrigerated Air Dryers for Pneumatic Tools & Controls
The header in a general manufacturing plant feeds three kinds of users at once: hand tools such as impact wrenches, grinders and nutrunners; the cylinders and valve manifolds on fixtures, presses and conveyors; and the regulators, positioners and I/P transducers that run the process. Water arriving with the air hurts each of them differently. It washes the oil out of a vane motor and rusts the vanes, it freezes at the exhaust port of a tool whose expanding air drops below 32°F, it pools in a cylinder and pits the bore, and it jams the 0.010 in orifices in a pilot valve or a positioner.
A refrigerated dryer holding a 38°F pressure dew point stops all of that inside a heated building, because nothing in the plant is colder than 38°F. That is ISO 8573-1 class 4 for water, the number most tool and valve makers print in their manuals. The exceptions are instrument lines that run outdoors and control air in an unheated building in winter, which need a desiccant stage.
Sizing starts with the compressor, not the tool count, because tools are intermittent and the compressor is what the dryer actually sees. A 30 hp rotary screw delivering 125 to 130 SCFM is a 150 SCFM dryer; a 75 hp screw at 320 to 340 SCFM is the 400 SCFM size. The dryer goes in the compressor room after the receiver, so every drop in the plant gets the same dry air.
Tool-heavy plants have the most variable air demand of any application on this site: the compressor loads and unloads all day as guns and wrenches come on and off. That is the duty where a cycling dryer earns its price, because its refrigeration compressor rests between bursts while the thermal mass carries the load.
Request a plant air dryer quote
margin below the coldest pipe for control airInside a plant held above 60°F a 38°F dryer clears that easily; a line to a rooftop damper in January does not, and needs a desiccant stage of its own.
What water does to tools and pneumatics
Four failures, all avoidable at 38°F
- Vane motors in grinders and impacts rust and lose torque as water washes the lubricant out
- Ice at tool exhaust ports on cold mornings, where the expanding air drops below freezing
- Cylinder bores pitting and seals hardening as condensate collects at the bottom of the stroke
- Solenoid and pilot valves sticking as rust slurry from a wet header blocks their orifices
The specification for tool and control air
What to write on the requisition
- 38°F pressure dew point, ISO 8573-1 class 4; desiccant only for outdoor or unheated lines
- Dryer sized to the compressor's full delivery at the compressor room's summer temperature
- 1 micron prefilter ahead of the dryer, 0.01 micron oil-removal afterfilter behind it for control air
- Zero-loss drains on the receiver, dryer and filter bowls, and a bypass so the dryer can be serviced
Dryers that fit tool and control air
Rated capacities at 100 psig and 100°F inlet. A 10 to 50 hp screw lands in the 65 to 250 SCFM band; a 60 to 100 hp compressor uses the 300 to 500 SCFM sizes. The cycling series suit the on-off demand of a tool-heavy plant.
| SERIES | TYPE | FLOW RANGE | MAX INLET | MAX PRESSURE |
| DXR Series | Non-Cycling | 10 to 4,200 SCFM | 131°F | 203 psig |
| FLXA Series | Cycling | 75 to 2,000 SCFM | 120°F | — |
| TMC Series | Thermal Mass Cycling | 30 to 635 SCFM | 140°F | 210 psig |
| NXC Series | Cycling | 20 to 2,000 SCFM | 158°F | 232 psig |
| HPRB Series | Non-Cycling | 7 to 50 SCFM | 120°F | 200 psig |
| GFN Series Filters | Compressed Air Filter | 6 to 1,500 SCFM | — | 232 psig |
| NGF Series Filters | Compressed Air Filter | 20 to 1,500 SCFM | — | 250 psig |
| ND Series Zero-Loss Drains | Condensate Drain | Call for sizing | — | 290 psig |
Plant air that reaches the tool dry needs three habits.
- Drops taken from the top of the header through a swan neck
- Receiver ahead of the dryer to soak up wrench and gun spikes
- Bypass valves tagged so service never leaves the dryer out
Take the drops off the top of the header
Even with a dryer in the compressor room, a header laid with a slight fall and drops taken from the bottom of the pipe deliver whatever liquid is in the line straight to the tool. Drops should leave the header from the top through a swan neck, the header should fall toward a drain leg at the far end, and that leg needs a drain that opens on its own.
The other habit worth breaking is the hose reel on the sunny side of the building. Air dried to 38°F and reheated in a hose lying in the sun will not condense in the tool; air that was never dried will, and the reel is the first place a plant notices that the dryer was bypassed for service and never put back.
- Top-entry drops with a swan neck
- Header falling to a drain leg with an automatic drain
- Bypass valves tagged so the dryer goes back in service
Where the dryer and filters go
Compressor, aftercooler, receiver, prefilter, dryer, afterfilter, header. The receiver ahead of the dryer matters more in a tool plant than anywhere else: it absorbs the demand spikes from a dozen impact wrenches so the dryer sees a smoothed flow instead of the compressor's full output every time it loads. Hand tools want a little oil and do not need the afterfilter, but control air, valve manifolds and any air that touches a finished part do, so the 0.01 micron oil-removal filter goes on the header behind the dryer.
Instrument and control air
The pneumatic control standard most instrument engineers work to asks for a dew point at least 18°F below the lowest temperature the air will meet anywhere in the system. Inside a plant kept above 60°F a 38°F dryer meets that with room to spare. A control line to a rooftop damper or a loading dock in January does not, and that branch needs a small desiccant dryer; the refrigerated versus desiccant page covers the choice.
Cycling or non-cycling for a tool plant
Tool demand is the classic swinging load: a fastening line pulls 60 SCFM for ten seconds and nothing for the next thirty. Over a shift the compressor may average half its rating, and overnight the plant holds pressure with almost no draw. A non-cycling dryer runs its refrigeration compressor flat out through all of it; a cycling dryer stores cold in a thermal mass and stops the refrigeration compressor whenever the air load is low. Above about 100 SCFM the saving pays for the difference within a couple of years.
Sizing for the compressor room
Take delivered SCFM off the compressor data sheet and the room temperature on the hottest afternoon of the year. At 110°F ambient an air-cooled dryer keeps about 88 percent of its rating, and a compressor with a dirty aftercooler can deliver 120°F air that takes the dryer down to 65 percent. A 40 hp screw at 175 SCFM in a 105°F room is the 200 or 230 SCFM dryer, not the 185; the flow and SCFM page shows the arithmetic.
Tool and instrument air, beyond the dryer
Yes. The dryer removes water, not the need for oil, and a lubricated vane motor still wants its film. What changes is that the oil stays where it is put instead of being washed out, so tools run longer between rebuilds and the bowls stop filling with a milky emulsion. Keep lubricators on the tool drops only; oil fed upstream of valve manifolds or control panels commits them to oiled air for life.
A common rule is 3 to 5 gallons per SCFM of compressor delivery on a load-unload screw, so a 30 hp machine at 125 SCFM takes roughly 375 to 625 gallons. That volume absorbs the bursts from wrenches and nutrunners, lets the compressor run longer cycles, and gives water time to drop out before the dryer. With too little storage the dryer sees the compressor's full output on every load cycle and its dew point swings with it.
Their nozzles and restrictors are a few thousandths of an inch across, and rust slurry or water from a wet header partly blocks them, so output pressure creeps away from the signal. The loop then hunts, and operators retune it rather than look at the air. Dry the header, put a fine filter-regulator at each instrument, and blow down the supply before reconnecting a cleaned device, or the first slug from the pipe undoes the work.
Usually the plant finds out from water at a hose reel or an FRL bowl a few days later. Faster signs are the dryer sitting cold and quiet while the compressor runs, and its panel indicator reading normal while it treats no air at all. Tag the bypass valves with a date and a name each time they are opened, and fit a dew point monitor on the header that alarms when the reading climbs.
Usually. A loop feeds every drop from two directions, so the air travels half as far at lower velocity, and pressure at the far end of the plant holds up when several wrenches start at once. Lower velocity also lets stray condensate settle toward the drain legs instead of riding into the drops. Slope each section to its own drain leg with an automatic drain, and keep taking every drop off the top of the pipe.
More on plant air for tools
Piping and bypass around the dryer
The order of equipment from compressor to header, and how to pipe a bypass that lets the dryer be serviced without stopping the plant.
Learn More
CNC & Machining
Machine shops run two shifts with the compressor loaded most of the time, which is the case where a non-cycling dryer costs nothing extra to run.
Learn More
Laser & Plasma Cutting
A plasma torch and a fiber laser cutting head both use compressed air as a process gas, and both punish wet air.
Learn More
