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.

Airman · SDG Series

Airman SDG25

Name: Airman SDG25
Brand: Airman
Availability: PreOrder

22 kW standby / 20 kW prime · Diesel · Liquid-cooled

20 kW prime diesel portable generator. Isuzu-powered with 32-hour runtime, 110% fluid containment, and switchable single/three-phase output.

Standby power: 22 kW / 20 kW prime
Voltage options: 120/240V, 208V, 240V, 277V, 416/480V
Frequency / Phase: 60 Hz · 1/3-phase
Engine: Isuzu 4LE2T · 2.2L
EPA / Emissions: Tier 4 Final

Commercialrental-fleettemporary-powereventsfilm-production

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Overview#

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 Platform#

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.

Our Service Experience#

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

Acoustic

Enclosure: Sound-attenuated

Fuel system & runtime

Integral fuel tank: 51.5 gal

Documents & downloads

Spec sheets & manuals

Spec sheet (datasheet)

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Estimate runtime for the Airman SDG25

Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.

Estimate runtime on this tank

Generator size

Fuel

Fuel tank capacity

gal

Load

Override full-load GPH (optional)

GPH

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.

Compatible equipment

Engine

Isuzu 4LE2TEngines

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Tier 4 Final portable diesel from 11 to 336 kW — Isuzu, Kubota, and John Deere engines with 110% fluid containment standard.

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