The Airman SDG125 is a 100 kW prime / 110 kW standby portable diesel generator powered by an Isuzu BR-4HK1X Tier 4 Final engine at 1,800 RPM. With a 168-gallon integral fuel tank, the unit runs 23.3 hours at full load — providing reliable overnight power for larger construction sites and emergency standby applications.
The SDG125 steps into the mid-range portable class at 6,702 lbs operating weight. Switchable output covers single-phase 120/240V through three-phase 480V configurations. Like all Airman generators, it features 110% fluid containment as standard and is designed for the 0.001% warranty claim rate that defines the Airman brand.
The Isuzu BR-4HK1X is a heavy-duty four-cylinder turbocharged diesel from Isuzu's commercial truck engine family, adapted for power generation duty. This engine platform is used globally in medium and heavy-duty trucks, which translates to exceptional parts availability and technician familiarity. In the SDG125 application, the BR-4HK1X runs at 1,800 RPM with Tier 4 Final emissions compliance. The engine's robust block and crankshaft design support extended overhaul intervals, contributing to the low total cost of ownership that justifies the Airman premium. At 100 kW prime, the engine operates at a moderate specific output, leaving ample reserve capacity for transient loads and hot-day derating.
The SDG125 is the workhorse of Airman's larger portable lineup in our Northern California fleet. We deploy it on major commercial construction projects — multi-story office buildings in San Francisco's SoMa district, hospital expansion phases at Stanford and UCSF, and data center commissioning work in Santa Clara and Fremont. The 100 kW prime rating is the threshold where most building-scale temporary power needs are met: full HVAC systems, elevator testing, fire alarm commissioning, and multi-floor lighting all run comfortably within the SDG125's capacity.
At 6,702 lbs, the SDG125 crosses into trailer-mounted territory for most deployments. The 168-gallon tank and 23.3-hour runtime keep fuel logistics manageable — weekly refueling on most projects. For units on extended deployments (60+ days), we follow the standard 250-hour oil change interval and recommend a mid-deployment coolant level check. The Isuzu BR-4HK1X has been very reliable in our fleet, with the primary maintenance focus being fuel quality management and battery health during storage periods between projects.
Engineering specifications
Physical
Length
113 in
Width
51 in
Height
73 in
Dry weight
5,379 lb
Wet weight
6,702 lb
Fuel system & runtime
Integral fuel tank
168 gal
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Get pricing & lead time on the Airman SDG125
Tell us about the application — kW, voltage, application, install timeline — and we'll respond within one business day with budgetary pricing, lead time, and any sizing notes.
Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.
Estimate runtime on this tank
Estimated runtime
28.3 hours(1.2 days)
Fuel consumption ≈ 5.94 GPH at 75% load. Estimate based on industry-typical 1800 RPM standby curves (≈0.07 GPH/kW at full load). Actual consumption varies by engine, ambient temperature, fuel quality, and tuning.
Service intervals
Manufacturer-recommended intervals for the Airman SDG125 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.
Oil & filter
Every 500 hours or 12 months
Air filter
Every 500 hours
Fuel filter
Every 500 hours
Major overhaul
≈ 20,000 hours
Common failure modes
What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.
Component
Symptom
Typical hours
Severity
Fuel filter
Clogging from contaminated or stale diesel causes hard starting and power loss — replace at 500-hour intervals or sooner if fuel quality is suspect
500+
minor
Starting battery
Capacity degradation during extended storage without a maintainer — test under load at every service visit and replace proactively at 36 months
4,380+
minor
Coolant hoses
Weeping at clamp points from thermal cycling — inspect during every oil change and replace at first sign of swelling or seepage
5,000+
minor
Frequently Asked Questions
What is the standby rating of the Airman SDG125?
The Airman SDG125 delivers 110 kW standby / 100 kW prime at 60 Hz (125 kVA). It provides switchable single and three-phase output across voltages from 120/240V through 277V and 416/480V.
What engine does the Airman SDG125 use?
The SDG125 is powered by an Isuzu BR-4HK1X — a heavy-duty four-cylinder turbocharged diesel from Isuzu's commercial truck engine family, adapted for power generation. Running at 1,800 RPM with Tier 4 Final compliance, it delivers strong transient load response and extended overhaul intervals.
What is Airman's warranty claim rate?
Airman generators are built by Hokuetsu Industries in Japan and carry a documented 0.001% warranty claim rate — the lowest in the portable generator industry. This figure reflects the precision manufacturing standards applied to every unit built at the Hokuetsu facility.
What are the service intervals for the SDG125?
The Isuzu BR-4HK1X engine in the SDG125 requires oil and filter changes every 500 hours or 12 months (whichever comes first), air filter replacement at 500 hours, fuel filter replacement at 500 hours, and is rated for major overhaul at 20,000 hours.
Is the SDG125 EPA compliant?
Yes. The Airman SDG125 meets EPA Tier 4 Final emissions standards through its Isuzu BR-4HK1X turbocharged engine. The unit is California-compliant for large commercial construction, emergency standby, and temporary data center power applications.
What fluid containment does the SDG125 have?
All Airman generators, including the SDG125, feature 110% fluid containment as standard. The integrated drip tray holds more than the total volume of all engine fluids, eliminating the need for separate secondary containment on California job sites.
Who services Airman generators in Northern California?
OnPoint Generators is the authorized Airman service provider for Northern California. We stock parts, perform warranty service, and offer maintenance contracts for the full Airman SDG lineup including the SDG125.
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