Series Overview#
The Atlas Copco QAS Series is a comprehensive line of 14 portable diesel generators spanning 22 to 616 kilowatts of standby capacity. Purpose-built for construction, rental, temporary power, and events, the QAS Series is distinguished by three consistent characteristics across the range: Tier 4 Final emissions compliance, Leroy Somer alternators with AREP excitation providing ±0.25% voltage regulation, and sound-attenuated enclosures that run 5–8 dBA quieter than most competing units in each power class.
The engine lineup is deliberately diversified: Isuzu engines at the small end (QAS 25–70), John Deere at the mid-range (QAS 95–330), FPT at specific mid-range ratings (QAS 175, QAS 235), Scania at the upper-mid range (QAS 410), and Volvo at the top of the line (QAS 625, QAS 700). This engine diversity is a design choice — Atlas Copco selects the engine best suited to each power rating rather than forcing a single engine family across the range. The result is that service access for any individual QAS model follows the respective OEM's dealer network — Isuzu, John Deere, FPT, Scania, or Volvo — in addition to Atlas Copco's own service infrastructure.
All QAS Series generators include 110% fluid containment and multi-voltage switching from 120V single-phase through 480V three-phase (some larger models are three-phase only). CARB compliance is standard, enabling deployment on California construction sites without restriction.
How to Choose#
The 14 QAS models form natural subgroups by engine family and power tier:
22–62 kW (QAS 25–70, Isuzu): The compact Isuzu-powered models. Consistent 67 dBA sound level across all three. The QAS 25 and QAS 45 share a platform with 75-gallon tanks for 48+ hours at 75% load. QAS 70 steps up to the Isuzu 4JJ1X with a 110-gallon tank. Multi-voltage from 120V to 480V. AREP alternators on all three. Choose this range for smaller construction sites, events, and light temporary power where noise level is a priority.
76–120 kW (QAS 95–125, John Deere 4045): Transition to John Deere power. The QAS 95 at 69 dBA and QAS 125 at 73 dBA — the latter is louder than the smaller models. Both use DOC/SCR aftertreatment for Tier 4 Final. The QAS 125 has a 166-gallon tank. Choose when 75–100 kW prime is needed and John Deere service access is preferred.
120–160 kW (QAS 150–200, John Deere 6068): Shared 335-gallon tank platform. QAS 150 provides 43+ hours at 75% load; QAS 200 provides 36+ hours on the same tank. The QAS 150 at 70 dBA is notably quieter than the QAS 125. Parts commonality between the QAS 150 and QAS 200 is a fleet management advantage. Both are available in 120/240V single-phase through 277/480V three-phase.
140–206 kW (QAS 175, 235, FPT N67): FPT-powered models at 69 dBA. Three-phase 277/480V only. QAS 175 at 140 kW prime; QAS 235 at 187 kW prime. Choose when FPT service access aligns with fleet service preferences.
200–264 kW (QAS 250–330, John Deere 6090): Shared 385-gallon tank. QAS 250 at 73 dBA, QAS 330 at 73 dBA. Both three-phase. Choose based on prime power requirement.
328 kW (QAS 410, Scania DC13): The sole Scania-powered unit. Three-phase 277/480V only. The Scania 12.7L inline-6 is a proven generator drive engine with a separate service network.
500–560 kW (QAS 625–700, Volvo): Flagship models on the Volvo TWD16 platform. The QAS 625 with a 707-gallon tank; QAS 700 at 76 dBA. The largest portable generators in the Atlas Copco US lineup. Tri-axle trailer platforms at approximately 26,000 lbs.
Common Applications#
- Construction (all project scales): All 14 QAS models are rated for construction. The 5–8 dB noise advantage makes QAS units the preferred specification on urban construction adjacent to occupied buildings or in noise-ordinance areas.
- Rental fleet: All 14 models are in active rental fleet service. The QAS Series' multi-voltage switching, AREP alternator quality, and Tier 4/CARB compliance make it a versatile specification for rental companies serving California and other regulated markets.
- Temporary power: Extended tank runtimes — up to 48+ hours at 75% load on smaller models, 43 hours on the QAS 150 — minimize operator intervention on multi-day temporary installations.
- Emergency standby: Six models specifically rated for emergency standby deployment. The AREP alternator's 300% overcurrent capability handles the high-inrush motor starting loads common in emergency situations.
- Events: The QAS Series' consistent low noise levels (67–76 dBA across the full range) make it the industry standard for outdoor events where generator noise is a guest experience concern.
Service & Maintenance#
All QAS Series generators share a consistent service schedule: oil and fuel filter changes every 500 hours or 12 months, air filter service every 500 hours. The Leroy Somer alternators are brushless with sealed bearings and require no brush or commutator maintenance.
The three consistent failure modes across the range are fuel filter restriction from contaminated diesel (documented in 14 models), starting battery degradation after extended storage (14 models), and coolant hose weeping at clamp joints (14 models). These are standby and rental fleet infrastructure issues — not engine failures. Fuel quality maintenance, battery maintainers between deployments, and hose inspection at each service are the three most impactful preventive measures.
Models using Isuzu 4JJ1X and larger Isuzu/John Deere engines include DEF (Diesel Exhaust Fluid) systems for Tier 4 Final compliance via SCR aftertreatment. DEF tank level must be monitored on active deployments — low DEF triggers progressive power derating per EPA requirements. Confirm DEF tank capacity and consumption rate with the individual model's spec sheet before planning refueling logistics.