High Pressure Air Compressors Above 30 Bar – Air Compressor Manufacturers

Regular industrial air pressure sits at 7-10 bar, covers bulk needs like pneumatic tools, spraying, material conveying. Beyond that enters medium-high pressure territory; above 30 bar is high pressure, above 40 bar ultra-high pressure.

High pressure industrial compressor system

Pressure Spectrum

From Medium to Ultra-High Pressure Applications

Pressure Segments and Typical Uses

10-15 bar medium pressure nothing special. Biggest user is laser cutting. Cutting carbon steel uses oxygen for combustion assist, cutting stainless and aluminum uses nitrogen auxiliary, thicker material needs higher pressure. Stainless above 12mm typically needs 12-16 bar, specific numbers in Trumpf or Bystronic parameter tables. Two-stage screw machines most common. Atlas Copco GA VSD+ series, Ingersoll Rand R series, domestic Kaishan and Xinlei all have models. Selection has no traps.

15-25 bar medium-high serves leak testing, high-pressure cleaning, some injection machine clamping. Two-stage screw can barely hit 20 bar; above that needs three-stage piston or boosters.

25-40 bar is where the real bulk of high pressure market sits. PET blow molding alone is over half the demand, rest goes to oil field injection, fire extinguisher filling, high-pressure leak testing. Multi-stage piston machines are mainstream, Kaishan, Xinlei, Hongwuhuan and imported Sauer, Bauer each have customers in this range. Few manufacturers pushed out 40 bar class screw machines, but rotor precision and shaft seal design barriers stay high, priced well above same-displacement piston machines, current installed base still small. Whether they can get a foothold in high pressure needs watching.

Above 40 bar is niche territory. 40-200 bar serves cylinder filling (firefighting, breathing air), burst testing, CNG refueling. Available tech paths basically just multi-stage piston and diaphragm compressors. Diaphragm machines have gas chamber completely isolated from drive mechanism; Beijing Zhongding Hengsheng, Hofer, Sera all have lines, position in purity-sensitive applications hard to replace. Above 200 bar is hydrogen refueling, research, military domain; from design review to acceptance whole process follows TSG 21 and GB 150, not ordinary compressor factory business.

High Pressure Applications Detailed

PET Blow Molding (30-40 bar)

Single largest application in high pressure compressed air by volume.

Primary Application

PET Blow Molding Lines

PET preforms heated to 90-110°C in infrared ovens to soften, sent into molds, high pressure air blown through stretch rod into preform cavity to inflate. Pressure's job is pushing softened PET against mold wall, fully replicating bottle shape and texture.

Pressure values depend on bottle type. Small bottles under 500mL usually need 25-30 bar, big water cooler bottles or complex shapes with ridges need higher. Often-overlooked issue here: tuning window is very narrow. 1-2 bar off and yield drops significantly; lightweight bottles especially sensitive. Preform weight already pushed very low, blow pressure deviates a bit, wall thickness distribution immediately goes uneven, whitened bottoms, over-thin shoulders, crooked necks all pop up. Process engineers on production lines spend way more time on parameter tuning than outsiders think. Supply system pressure stability directly affects their tuning margin.

Usage rhythm has strong pulse characteristic. A 16-cavity blow molder puts out twenty thousand bottles an hour, each bottle takes several liters of high pressure air, multiply by output that's sustained high flow demand, drawing air in bursts. Sidel and Krones high-speed lines have tight requirements on supply system peak flow and pressure stability. Air receiver capacity is key variable; common practice sizes tanks at 1/3 to 1/2 of compressor discharge, then adjusts for blow molder cavities and cycle time. Tank too small means big pressure swings, directly hits yield.

Oil content control can't slack. PET bottles hold drinks and food directly, residual oil on inner wall is quality incident. ISO 8573-1 Class 1 requires oil ≤0.01mg/m³, systems come standard with high pressure refrigerated dryers and multi-stage filtration including activated carbon. During operation watch filter differential pressure. Clogged elements have two impacts: oil potentially over spec is one, actual supply pressure eaten by pressure drop with blow molder sensing reduced pressure is another. Latter usually gets noticed first by production staff.

Air recovery systems increasingly common on new lines in recent years. After blowing a bottle, high pressure air inside just vented, all that energy wasted. Recovery devices take blow molding exhaust (pressure already dropped to around 7-10 bar) and feed back to low pressure main for other equipment. Sidel's AirRecycle and SMI's Air Recovery both work this way. Manufacturers claim 15-25% drop in total energy use; actual varies a lot across lines, depends on uptime and whether low pressure end usage matches. But as long as line uptime is high enough, payback generally within two years.

Leak Testing (20-60 bar varies)

Compared to blow molding, leak testing system setup is much simpler.

Pressure test multiplier per GB/T 150.4 or product design spec, usually 1.5 times working pressure. Usage pattern is charge-hold-release cycle, frequency irregular, sometimes dozens in a row, sometimes nothing for half a day. Bottleneck for the system isn't compressor discharge but tank buffering and regulator precision. If source end pressure is still wobbling during hold phase, can't tell if pressure drop is test piece leaking or supply variation. So big tank, high regulator precision (±0.5%F.S. or better). Compressor here is more like a "tank filler," actually the least critical piece.

Breathing Air

Diving Cylinders

Filling Stations

Breathing Cylinder Filling (200-300 bar)

Positive pressure breathing apparatus for firefighting, diving, mine rescue, cylinder specs commonly 6.8L/30MPa and 9L/30MPa. 6.8L cylinder filled to 300 bar stores about 1,300+ standard liters of air (gas deviates from ideal at high pressure, less than PV=nRT theory), good for 40-50 minutes breathing at moderate exertion.

This application is tougher than blow molding and leak testing, tough part is air quality. People breathe this directly. EN 12021:2014 limits CO to 5mg/m³, puts high demands on catalytic oxidizers. Catalytic oxidizer is core CO removal component; catalyst activity degrades over time, faster in areas with bad air pollution. Some filling stations located near urban or industrial zones, ambient CO baseline already elevated, actual catalyst load way above what manuals assume for clean air. After a year or two, output CO slowly creeps up. If filling volume is low and calendar time hasn't hit cartridge swap interval, this change goes unnoticed. Training repeatedly says manage cartridge replacement by filling volume not calendar time; how many filling stations actually do that varies.

EN 12021 also requires CO₂≤500mg/m³, oil ≤0.5mg/m³, dew point at least 5°C below lowest use environment, no odor. These are less hard than CO; properly maintained systems usually no problems.

Bauer and Coltri Sub have big market share in breathing air filling; domestic brands catching up in recent years. Three or four stage compression with reciprocating piston structure, ratio roughly 3.5-4.2 per stage. Filling done cylinder by cylinder on dedicated racks; cylinders with expired inspection marks or visible dents, cracks, corrosion never get filled.

Technical Challenges of High Pressure Machines

Biggest difference from regular pressure is multi-stage compression and intercooling. Compressing from atmospheric to 40 bar in one shot pushes discharge temp above lube flash point and seal material temp limits, simply can't do it. Split into stages with ratio 3-4 each, water or air cooling between stages drops gas temp to 40-50°C before next stage, temps become manageable.

Intercooling causes more operational trouble than design anticipated. Cooling water temp varies by season; summer water temp high, intercooler can't drop temp low enough, final stage discharge rises with it. Some filling stations and blow molding shops in the south need to run extra chillers in July-August to lower water temp, otherwise high temp alarms and frequent shutdowns. Heat exchanger tube scaling is another thing, unrelated to season, related to water quality. Poor water quality areas need cleaning every six months to a year. Skip it and heat exchange efficiency keeps dropping, discharge temp slowly rises, boiling frog situation, often only noticed when alarm triggers.

Oil-Flooded Path

Lower Cost, More Post-Treatment

Oil-flooded with good post-treatment filtration to push oil below spec, overall costs lower. Suitable for non-breathing, non-food applications.

Oil-Free Path

Higher Cost, Shorter Ring Life

Uses self-lubricating materials instead of lube oil; manufacturing costs higher, piston ring life shorter, maintenance more frequent. Required for breathing air and food-grade.

Sealing and lubrication importance in high pressure piston machines is totally different magnitude from regular pressure. Final stage piston rings see tens to over a hundred bar pressure differential across them; regular PTFE can't handle it, needs filled PTFE with bronze powder or carbon fiber, some makers use multiple seal rings for staged pressure drop. Wear rates much faster than regular pressure. Lube oil selection for final stage high temp and pressure is also tricky, needs viscosity retention, oxidation resistance, low volatility all at once, narrow range of oils meet all requirements.

Oil-flooded vs oil-free is unavoidable debate in high pressure piston selection. Oil-free uses self-lubricating materials instead of lube oil; manufacturing costs higher, piston ring life shorter, maintenance more frequent. Breathing air filling and food-grade blow molding basically have to go oil-free. Other applications can use oil-flooded with good post-treatment filtration to push oil below spec, overall costs lower. Both paths have advocates and both have merits.

Safety discussion last, not because unimportant. Compression energy in high pressure gas is serious; a 50L/40bar receiver suddenly releasing equals expansion work from 2,000 liters atmospheric gas. Pipe weld quality, tank wall thickness calc, safety valve setting, rupture disc setup, any step having problems is serious consequences. This isn't really about equipment selection but about install and operation, discuss together in safety section later.

System Architecture

Three Approaches to High Pressure Air Source

These three approaches ultimately come down to economics: how much high pressure air needed, how often, what existing equipment.

High volume continuous operation, typically PET blow molding lines, basically can only choose dedicated high pressure compressor, compressing straight from atmospheric to target pressure. High investment, big footprint, needs independent maintenance system.

Factory already has low pressure compressor station and high pressure demand is small, boosters are money-saving option, detailed in next section.

Also high pressure storage plus pressure regulation: high pressure compressor pre-fills big capacity receiver, regulator drops pressure for output during use. Receiver acts as energy accumulator, compressor slowly fills during non-use periods. Leak test stations and small batch blow molding lines often use this, very suitable for high instantaneous demand short duration. Receiver capacity must cover worst-case continuous use scenario; undersized tank means pressure drops below minimum and supply cuts, production line waiting costs way more than buying bigger tanks.

In practice three approaches can mix. Some factories have dedicated high pressure machines on main lines for capacity, use boosters for occasional high pressure needs in labs or auxiliary stations.

Booster Principles and Applications

Boosters don't draw atmospheric air, they take 7-10 bar compressed air from low pressure station and compress again to 30-40 bar, boost ratio kept within 4-5 times, achievable single stage.

Savings come from not building new high pressure station. One booster hooked to existing low pressure main with a high pressure receiver can provide high pressure locally. Equipment compact, lots of models tuck right next to point of use. Maximator been in industrial boosting for years, several domestic players too. When selecting focus on match between boost ratio, flow curve, and inlet pressure; nameplate max discharge is optimal conditions number, on site inlet pressure fluctuation and pipe losses need factoring in.

Often-overlooked issue: boosters eat compressed air, not free atmosphere. Every 1 Nm³ of 40 bar air takes about 4-5 Nm³ of 8 bar from the low pressure main. High pressure use ramps up, load on low pressure station gets pulled up. This linkage often missed during scheme review, only discovered after boosters installed and running when low pressure main pressure drops and previously fine low pressure equipment starts complaining about insufficient pressure. Verify low pressure station surplus before adding boosters, essential homework.

Boost ratio above 5 times, single-stage boosting has elevated discharge temp and seal loads, either go to two-stage boosting or this path dead ends and you're back to dedicated high pressure machines.

High Pressure System Safety Requirements

Safety valve set pressure can't exceed vessel design pressure, calibration per TSG 21-2016 usually annually. Pressure gauge range 1.5-3 times working pressure, 0.4 or 1.0 accuracy class for high pressure systems.

Overpressure interlock must be independent of normal control loop. Pressure signal from separate transmitter, when exceeded directly cuts compressor power or opens unloader, doesn't go through PLC. Why stress this? PLC itself can fail, program can be changed, communication can delay; if interlock depends on PLC that's another failure layer added. Principle accepted during design, but during on-site commissioning for wiring convenience or unified display, interlock signal gets routed through PLC. Happens.

In-service inspection cycles for piping and receivers 3-6 years, wall thickness measurement, weld NDE, safety accessory check are core.

Operations level, personnel need certification. Daily rounds use leak detection fluid or ultrasonic leak detector to check sealing points at flanges, fittings, valves. Depressurize before maintenance, confirm pressure is zero and isolated from source before taking apart. Pressurized disassembly incidents reported every year; everyone understands the principle, incidents often happen rushing schedule or thinking "pressure isn't that high, it's fine."

Filling stations for firefighting and diving have their own filling qualification requirements and procedures beyond general pressure vessel regs. Before building station, figure out qualification application pathway first. Cases of equipment ready but can't operate stuck on qualification have happened more than once.