The Airman SDG25 is a 20 kW prime / 22 kW standby portable diesel generator powered by the Isuzu 4LE2T turbocharged engine at 1,800 RPM. It delivers switchable single-phase and three-phase output with automatic voltage regulation within ±0.5%, making it suitable for sensitive equipment on construction sites.
The SDG25 runs 32 hours at full load on its 51.5-gallon integral tank — the longest runtime in its class. Standard 110% fluid containment meets California environmental requirements without aftermarket additions. At 2,205 lbs operating weight, the unit is towable behind a standard pickup truck.
The Isuzu 4LE2T is a 2.2-liter turbocharged four-cylinder diesel purpose-built for the compact equipment market. Its common-rail fuel injection system delivers precise fuel metering that translates directly into the SDG25's class-leading 32-hour runtime. Running at 1,800 RPM, the engine operates well within its design envelope, which contributes to the extended overhaul intervals and low warranty claim rate that define the Airman brand. Tier 4 Final compliance is achieved without a diesel particulate filter, keeping the exhaust aftertreatment system simple and maintenance-free for field crews.
The SDG25 is our most-requested Airman model for Northern California construction and event work. We see it deployed on everything from Peninsula residential remodels to Napa Valley vineyard events and San Francisco commercial tenant improvement projects. The 32-hour runtime means crews can mobilize on a Friday afternoon and run through the weekend without a fuel stop — a significant operational advantage over competing 20 kW units that need refueling after 18-24 hours.
Service patterns on the SDG25 are straightforward. The Isuzu 4LE2T is forgiving of varying load profiles, but fuel quality remains the primary maintenance driver. Units that move between job sites frequently should have their fuel filters inspected at 250 hours rather than waiting for the 500-hour interval, especially during the wet season when condensation in partially filled tanks accelerates water contamination. Battery health is the other recurring service item — a float charger between deployments prevents the majority of no-start service calls.
Engineering specifications
Physical
Length
67 in
Width
31 in
Height
55 in
Dry weight
1,808 lb
Wet weight
2,205 lb
Fuel system & runtime
Integral fuel tank
51.5 gal
Request a quote
Get pricing & lead time on the Airman SDG25
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
43.4 hours(1.8 days)
Fuel consumption ≈ 1.19 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 SDG25 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 SDG25?
The Airman SDG25 delivers 22 kW standby / 20 kW prime at 60 Hz. It provides switchable single and three-phase output across voltages from 120/240V through 277V and 416/480V.
What engine does the Airman SDG25 use?
The SDG25 is powered by an Isuzu 4LE2T — a 2.2-liter turbocharged four-cylinder diesel running at 1,800 RPM with EPA Tier 4 Final compliance. The common-rail fuel injection system delivers precise fuel metering that contributes to the SDG25's class-leading 32-hour runtime.
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 SDG25?
The Isuzu 4LE2T engine in the SDG25 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 SDG25 EPA compliant?
Yes. The Airman SDG25 meets EPA Tier 4 Final emissions standards through its Isuzu 4LE2T turbocharged engine — without requiring a diesel particulate filter regeneration cycle. The unit is California-compliant for construction and event applications.
What fluid containment does the SDG25 have?
All Airman generators, including the SDG25, 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 SDG25.
Similar models
Airman
Airman EBOSS 25-25
Only integrated diesel-battery hybrid portable generator on the market — LTO batteries, unlimited paralleling, dramatic fuel and emissions reduction.
22 kW standby · Diesel · Liquid-cooled
Noise-sensitive urban construction, events, and sites where fuel cost and emissions matter.
25 kVA hybrid energy system with 25 kWh LTO battery storage. Diesel-battery hybrid for reduced fuel and emissions.
3-phaseconstructionrental-fleet
Airman
Airman SDG25SV V-Pump
Industry-leading 0.001% warranty claim rate with 110% fluid containment standard — no separate secondary containment needed on CA sites.
22 kW standby · Diesel · Liquid-cooled
Rental fleets and construction sites requiring ultra-reliability and environmental compliance.
25 kVA (20 kW prime) portable diesel generator with integrated VFD for motor starting and dewatering.
Tier 4 Final3-phaseconstructionrental-fleet
Airman
Airman SDG40
0.001% warranty claim rate, 110% fluid containment standard, 37-hr runtime in the same footprint as the SDG25 — maximum power density with lowest total cost of ownership.
30 kW standby · Diesel · Liquid-cooled
Mid-range 29 kW portable for construction sites needing more power without a larger footprint. Ideal for commercial TI projects, utility work, and multi-day unattended temporary power.
28.6 kW prime diesel portable generator. Kubota-powered with 37-hour runtime at full load and 110% fluid containment standard.
Tier 4 Final3-phaseconstructionrental-fleet
Need service or parts for the Airman SDG25?
We service every major OEM and stock genuine parts for the most common models.
