Overview#
The Atlas Copco QAS 625 is the flagship of the QAS portable lineup, delivering 500 kW of prime power from a Volvo TWD1672GE 16.1-liter diesel engine. It is the largest mobile generator Atlas Copco offers in the North American market, mounted on a tri-axle trailer platform at approximately 26,000 lbs.
The AREP alternator excitation system provides 300% overcurrent starting capabilities for high-inrush motor loads. The 707-gallon integral fuel tank with 110% fluid containment supports extended runtime for large construction projects, data center temporary power, and emergency standby applications. SCR-only aftertreatment keeps the Tier 4 Final system simpler than DPF-equipped competitors.
SCR-only aftertreatment advantage#
The QAS 625 uses SCR-only (Selective Catalytic Reduction) aftertreatment for Tier 4 Final compliance — no diesel particulate filter (DPF). This is a meaningful advantage over DPF-equipped competitors. DPF systems require periodic regeneration cycles that can interrupt operation and add maintenance complexity. The SCR-only approach on the Volvo TWD1672GE requires DEF (Diesel Exhaust Fluid) but avoids regeneration-related downtime and the associated ash cleaning intervals that DPF systems demand.
For data center and critical temporary power applications, the absence of a DPF reduces the risk of unexpected shutdowns from failed or incomplete regeneration cycles. The 500-hour service intervals and the Volvo engine's established industrial reputation make the QAS 625 a lower-maintenance flagship compared to alternatives with more complex aftertreatment systems.
Our service experience#
The QAS 625 is a serious piece of equipment — 26,000 lbs on a tri-axle trailer with a 16.1-liter Volvo engine. Service on units this size requires specialized capabilities, and this is where Atlas Copco's after-sale service weakness becomes most impactful. At 500 kW, every hour of downtime is expensive, and the factory network's pattern of unreturned calls, high travel charges ($311+/hour), and multi-week parts delays is simply not acceptable for critical applications.
The Volvo TWD1672GE engine does benefit from Volvo's industrial engine dealer network for engine-specific service, which provides an alternative channel for major engine work. However, Atlas Copco-specific components — enclosures, control systems, AREP excitation components — must come through Atlas Copco's own supply chain. For QAS 625 owners in Northern California, OnPoint provides local service support with the capability to handle large mobile units and experience across the full QAS lineup from 20 kW to 500 kW.
