Air Compressors for Packaging Lines

Air source config for packaging lines looks simple: add up equipment air use, pick a big enough compressor, done. Actual operation has plenty of pitfalls.

The Blow Molding Machine Problem

Lots of packaging line air source plans go wrong from the start because blow molding machines get mixed in with other equipment.

Blow molders need high pressure air above 25 bar; some thin-wall bottles go to 38 bar. Regular screw compressor output is 7-8 bar, nowhere near enough. A line doing twenty thousand bottles an hour consumes high pressure air equivalent to the total of over a dozen downstream packaging equipment combined. This needs dedicated high pressure piston machines on independent systems; don't mix it with the screw machine setup.

Pre-blow uses low pressure that can tap from common main at 8-10 bar, include in overall planning.

Air volume calcs below default to excluding blow molders, handled separately.

The Air Consumption Math

Filling machine air consumption swings big. Small 4-head machines might not hit 0.4 cubic meters, 24-head high-speed lines can run to 1.8 or even 2 cubic. This number must come from equipment suppliers; don't guess.

Sealing section equipment, cappers, crimpers, heat sealers, single units 0.15-0.6 cubic, usually totaling under 1.5 cubic together.

Labelers and coders save air; two labelers plus one coder, 0.4 cubic max.

Equipment

Filling Section

End of Line

Palletizing System

Case packers bring consumption back up downstream. Box forming plus product loading, multiple cylinder groups acting together, 0.8-1.4 cubic unavoidable. Palletizers depend on gripper type: clamp style around 0.5 cubic, suction cup can hit 1.8 cubic. Case sealers and stretch wrappers together 0.4 cubic, treat as rounding.

Inspection and reject devices have negligible air use in calcs, unless reject rate high enough that reject device fires frequently.

List it up:

Equipment Air Use (m³/min): Filling machine 1.05, Capper + Crimper + Heat sealer 0.85, Labelers ×2 + Coder 0.38, Case packer 1.15, Palletizer 1.25, Case sealer + Stretch wrapper 0.42, Total 5.1

Air Quality in Two Tiers

If filling machines have purge function, purge air enters bottles and touches product. This needs ISO 8573-1 Class 1, hard specs on particulates, oil, dew point. Terminal gets 0.01 micron precision element plus activated carbon filter, or feed this station separately from oil-free compressor.

Rest of cylinders, valves, reject devices where air doesn't touch product: Class 3 enough. Refrigerated dryer plus standard three-stage filtration, nothing special.

Labeling Station Air Source Prone to Problems

This spot sometimes has inexplicably high failure rate.

Labels separate from backing and get blown onto product by airflow. Air volume small but sensitivity to dryness high. Water in air makes label paper absorb moisture and curl; stuck on but not flat, lifts up on its own later. Oil is worse; oil on adhesive means won't stick at all.

Some factories have persistently high labeling rejects. Equipment makers come check forever finding nothing wrong; finally discover it's compressed air. Add condensate separator and oil removal element at terminal, problem gone.

Coders similar. Ink channels are fine; particulates and moisture easily cause blockage. Root causes of common coder failures often aren't in the machine itself.

Supply Stability

Packaging line downtime costs aren't just your own output loss.

Two compressors as mutual backup is standard. One VFD one fixed-speed combo common: VFD normally follows load, fixed-speed kicks in during peaks for extra flow, either can independently sustain basic production during faults.

Pipe pressure drop shows up on long packaging lines. From filling to palletizing stretching sixty to seventy meters or over a hundred, 7 bar at front may be only 6.2-6.3 bar at back end, some cylinder actions get sloppy. Ring main more even than single-end feed; size pipes for flow velocity under 15m/s.

Receiver capacity matched to total discharge: 6 cubic system matches 1000-1500 liter tank. Position after dryer out, before main pipe branches; buffers load swings and makes sure everything entering main is treated dry air.

Large vs Small Line Config Differences

Small lines under 5 cubic are simple: one or two small screw compressors plus refrigerated dryer plus filters, food contact points get precision terminal element. Product sensitive, use small power oil-free; 7.5kW, 11kW class prices not that crazy anymore.

Large lines above 15 cubic: three or more compressors under coordinated control, auto-dispatching starts and stops by network pressure. Long lines suit zoned supply: one route for high sanitary filling area, another for regular case packing and palletizing. Config entire line to highest standard wastes money; zoned is more economical.