Atlas Copco ZR / ZT Oil-Free Screw
Two-stage gear-driven oil-free rotary screw. Used where 100% oil-free air is mandatory. 20–1,200 hp.
Type
Oil-free rotary screw
Power
20–1,200 hp
Flow
80–5,300 cfm
Pressure
60–188 psig
Cooling
air-or-water
Drive
gear
Lubrication
oil-free
Models
ZR/ZT 15–900
Years produced
Platform in continuous evolution since 1980s; current generation ~2015.
Sound level
~69–83 dB(A) @ 1 m depending on frame.
Dimensions
Frame-dependent; largest units ship as skid modules > 10 ft long.
Weight
ZR 55 ~4,500 lb; ZR 250 ~15,000 lb; ZR 900 approaches 40,000 lb.
Ambient range
40–115 °F standard.
Motor efficiency
IE3 / NEMA Premium standard.
Integrated dryer
Optional integrated MD adsorption dryer for -100 °F PDP Class-0 air.
Warranty
AIRPlan / OEM contract options — factory airend rebuild scheduled per Atlas Copco program.
Control modes
- Load/Unload
- VSD (variable-speed variants)
Typical applications
- Pharma
- Semiconductor
- Food & bev
- Textile
- Automotive paint
Specs & intervals below are from publicly published OEM literature and long-standing field practice. Torque values, exact revision-dated part numbers, and safety-critical settings vary by serial number — always cross-check the unit’s OEM manual and nameplate before ordering parts or performing service.
Fluid
Spec: Atlas Copco Roto-Xtend Duty Oil (gearbox only — not in air stream)
Change interval: 8,000 hr
Approved alternatives
- Roto-Xtend Duty Ultra
Wear parts
| Category | Interval | Source |
|---|---|---|
| Air filter (heavy-duty) | 4,000 hr | |
| Gearbox oil filter | 4,000 hr | |
| Intercooler cleaning | Annual | |
| Airend rotor coating inspection | Per OEM major overhaul interval (typ. 40,000 hr) | |
| Blowoff valve seat | 16,000 hr | |
| Check valve (inter- & aftercooler) | Annual inspect |
Consumable part numbers change by revision and region — pull the current number from the OEM portal.
Preventive maintenance
Daily
- Check gearbox oil level
- Verify condensate drain function on intercooler & aftercooler
- Log first and second stage temps
Every 4,000 hr
- Change gearbox oil filter and air filter
- Clean intercooler & aftercooler
- Sample gearbox oil
Every 8,000 hr
- Change gearbox oil
- Inspect check valves and blowoff valves
- Verify airend clearances per OEM procedure
Every 40,000 hr
- Factory airend overhaul (rotor coating, timing gears, bearings)
Common faults & first checks
- Second-stage temp high — intercooler plugged or bypass valve stuck
- Airend rotor coating degradation past overhaul interval — plan factory rebuild
- Blowoff valve stuck on unload — high energy waste (audible venting)
- Timing gear backlash growth — flag for factory service
Known issues & field notes
- Water-cooled ZR fouling in hard-water plants — spec plate-and-frame with easy access
- Long-term storage requires nitrogen purge to prevent internal corrosion
Controller(s)
- Elektronikon Mk5 / Mk V (Graphic & Touch) — Graphic: 3.5" (small frames) or 4.3" (larger) TFT color, hard buttons. Touch: 7" capacitive TFT with icon menu.
Strengths
- Class-0 certified oil-free air for pharma / food / electronics
- Very high reliability at spec'd overhaul intervals
- Wide VSD variants for turndown
Weaknesses
- Airend rebuild is factory-only
- High capital cost
- Long lead time for scheduled overhaul
Field notes
ZR = water-cooled, ZT = air-cooled. Two-stage design with intercooling between stages. Airend uses precision timing gears and coated rotors — no oil in the air stream.