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Quotes - Engineering - SalesFood, Beverage & Pharma
Contact Air and Non-Contact Air
Compressed air drying for packaging, bottling, brewing, pharmaceutical and dairy plants
Food and pharmaceutical plants divide their compressed air into air that touches the product and air that does not, and the two get different specifications. Non-contact air runs the cylinders on a case erector, the valve actuators in a cellar and the instrument loops on a pasteurizer; the food-grade codes of practice most auditors work to ask for ISO 8573-1 class 2.4.2 there: particles to class 2, a 38°F pressure dew point, oil to 0.1 mg per cubic meter. Contact air blows a bottle clean, fluidizes a powder or breaks a sterilizer vacuum, and the same codes ask for class 2.2.1: a –40°F dew point, oil to 0.01 mg per cubic meter and a sterile filter at the point of use. A refrigerated dryer with a 0.01 micron coalescer and an activated carbon filter delivers class 2.4.1 for the whole plant; the –40°F contact air is a desiccant dryer downstream of it, fed by it.
- Refrigerated dryer at the compressor room for every non-contact use: 38°F, class 4, with coalescing and carbon filters for oil class 1
- Desiccant stage and sterile filter on the branches that touch product, sized for that branch alone
- Cold rooms, cellars and chilled packaging halls sit below 38°F: those lines condense on a refrigerated dew point and need the desiccant branch too
Five Applications
Pick the Page for Your Plant
Each page below covers the air-using equipment on that line, what water and oil do to the product and the process, the compressor size and flow behind it, the classes the contact and non-contact air need, where the dryer, filters and desiccant branch go, and the series that fit. An oil-free compressor does not change any of it: oil-free air is still saturated with water, and the dryer is the same. Most of these plants land on the DXR non-cycling series, the FLXA and NXC cycling series, the AES digital-scroll dryers for the larger halls, the HF and GFN filters and the ND zero-loss drains, with a PDM dew point monitor to prove the class on paper.
Cold Rooms Below the Dew Point
The refrigerated dryer's 38°F dew point is the limit that matters in these plants, because so much of the building is colder than that. A beer cellar at 34°F, a dairy cold store at 36°F, a chilled packaging hall at 45°F with an air line running along its ceiling: every one of them will condense water inside a line carrying 38°F air, and the valve actuator or cylinder at the end of that line gets the water. The refrigerated dryer is still doing its job; the line is simply colder than its dew point.
The answer is not to abandon the refrigerated dryer but to add a desiccant stage on the branch that enters the cold space, fed by the refrigerated dryer so the desiccant bed sees a tenth of the water load and purges accordingly. The plant air stays on the refrigerated dryer, which is cheaper to run and simpler to keep, and the cold branch and the product-contact branch get their –40°F from a unit sized for that branch alone. The refrigerated versus desiccant page sets out which duties fall on each side of that line.
Series That Carry Food and Pharma Duty
Plants to 250 SCFM: the DXR non-cycling series and the TMC and NXC cycling series for breweries, small packagers and pilot plants. Halls to 1,250 SCFM: the DXR sizes and the FLXA cycling series, water-cooled where the compressor room runs hot. Central plants to 10,000 SCFM: the AES digital-scroll dryers and the VDR variable-speed series, whose refrigeration follows the swing between CIP cycles and production. Every one is on the refrigerated dryers page with its ratings and part numbers.
Around the dryer: HF and GFN prefilter and afterfilter pairs with 0.01 micron and activated carbon elements for oil class 1; the GF WS centrifugal separator ahead of the dryer on a wet system; ND zero-loss drains at every low point, because a timer drain on a 24-hour plant vents air all year; and the PDM dew point monitor, which reads the outlet dew point on site and gives an auditor a number rather than an assurance. The accessories page groups them by dryer size.
Typical Range Across Food, Beverage and Pharma Plants
Starting points, not limits. Flow is the compressor's delivery at 100 to 125 psig; contact air and chilled-room branches take a desiccant stage after the refrigerated dryer.
| APPLICATION | TYPICAL COMPRESSOR | DELIVERED FLOW | DEW POINT NEEDED | DRYER BAND THAT FITS |
| Food packaging | 25–150 hp rotary screw | 100–700 SCFM | 38°F class 4 non-contact; –40°F class 2 for contact air and chilled halls | 300–1,250 cycling |
| Bottling & canning | 50–300 hp screw, plus high pressure for PET | 200–1,250 SCFM | 38°F class 4 for machine air; class 2 with a sterile filter for rinser air | 300–1,250, high pressure |
| Breweries & wineries | 10–50 hp rotary screw | 40–230 SCFM | 38°F class 4 in the packaging hall; desiccant for cellar branches below 38°F | 20–250 SCFM cycling |
| Pharmaceutical | 25–150 hp oil-free screw | 100–700 SCFM | 38°F class 4 utility air; class 1.2.1 with a sterile filter for product contact | 300–1,250 SCFM |
| Dairy processing | 40–200 hp rotary screw | 175–900 SCFM | 38°F class 4 in the process hall; desiccant for cold rooms and contact points | 300–1,250 cycling |
Contact air and cold branches, answered
Treat it as contact air. It flows into a chamber holding product or packaging that has just been sterilized, so whatever it carries lands on a clean surface. The codes most auditors follow put that service at class 2.2.1, with a sterile filter at the point of use. The flow is small and intermittent, so the desiccant stage for it is sized for that branch alone and fed from the refrigerated dryer, not sized for the plant.
Last, at the point of use, after the desiccant dryer and its particulate afterfilter, so nothing downstream can add contamination before the air meets product. Ahead of it, the coalescing and particulate stages protect the sterile element from oil and dust that would shorten it's life. Mount it where it can be inspected and changed without opening the line to the room, and record each change alongside the dew point readings in the audit file.
Only as large as the cellar's own draw, which is valve actuators and a few cylinders, often a small fraction of the plant's flow. Fed from the refrigerated dryer, the desiccant bed sees roughly a tenth of the water it would see on saturated air, so a modest unit purges lightly and holds -40°F. Sizing it for the whole compressor is the common mistake: it costs more, and its purge loss is paid on air the cellar never uses.
As oily wastewater unless the compressor is oil-free. Condensate from a lubricated screw carries emulsified lubricant, and most sewer authorities will not accept it untreated, so the zero-loss drains discharge to an oil-water separator first. In a plant running 24 hours that separator sees a steady flow all year. Pipe each drain line to it with a visible break at the inlet, so a blocked line shows itself instead of backing up.
