Blue Star Power Systems · Gaseous Product Line (PSI 21.9L)

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Blue Star NG425-01

425 kW standby · Natural Gas / LPG · Liquid-cooled

425 kW natural gas / LP standby generator from Blue Star Power Systems. PSI 21.9L V12 turbocharged-aftercooled, DSE DCP7310 controller, three-phase 208-600V.

Standby power
425 kW
Voltage options
120/208V, 240V, 277/480V, 347/600V
Frequency / Phase
60 Hz · 3-phase
Engine
PSI 21.9L · 21.9L
EPA / Emissions
EPA Stationary Spark Ignition
Alternator
Stamford S4L1D-G41
large-commercialdata-centerhospital-non-criticalhotelschool-campusmulti-family-largelight-industrial

Overview#

The Blue Star NG425-01 is a 425-kilowatt natural gas / LP standby generator built on the PSI 21.9-liter V12 platform. It is rated 425 kWe standby on natural gas and 300 kWe on LP at 60 Hz / 1800 RPM. Three-phase only (208V, 240V, 480V, 600V). This model shares its engine, footprint, and enclosure with the NG400-01 and NG450-01, providing stepped standby capacity on the same physical base.

The PSI 21.9L V12#

The PSI 21.9L is a 1,338-cubic-inch (21.9-liter) V12 turbocharged-aftercooled spark-ignition engine:

Alternator configurations#

VoltagePhaseAlternatorConnection
120/208V3Stamford HCI534D12-lead WYE
240V3Stamford HCI534D12-lead DELTA
277/480V3Stamford S4L1D-G4112-lead WYE
347/600V3Stamford HCI534C4-lead WYE

All configurations carry 125°C standby temperature rise and ±0.5% voltage regulation.

When to spec the NG425-01#

Our service experience#

The PSI 21.9L V12 is one of the highest-volume platforms in Blue Star's large-gaseous line. Service procedures — spark plugs, ignition coils, charge-air cooler hoses, oil and air filters — are consistent with the NG400-01. The DSE DCP7310 controller is identical across the NG400/425/450 range, keeping technician training requirements flat across units.

Engineering specifications

Physical

Length
156 in
Width
86 in
Height
98 in
Dry weight
10,925 lb

Acoustic

Sound @ 7m, full load
87 dBA
Enclosure
Open

Fuel system & runtime

NG required pressure
11 in WC

Thermal & ventilation

Heat to coolant
1,760,700 BTU/hr
Heat radiated
524,640 BTU/hr
Exhaust flow
2,529 CFM
Exhaust temp
1136 °F
Combustion air
829 CFM
Ventilation air
39,995 CFM

Documents & downloads

Spec sheets & manuals

Request a quote

Get pricing & lead time on the Blue Star NG425-01

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.

Estimate runtime for the Blue Star NG425-01

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

Estimate runtime on this tank

Fuel demand at 75% load

4,462,500 BTU/hr4462.5 cf/min @ 1,000 BTU/cf

On utility natural gas the runtime is generally unlimited provided the supply line and meter can deliver this BTU/hr at the engine's required inlet pressure (typically 5–14" WC residential, up to 5 psi commercial). Confirm against the OEM's published fuel-pressure spec.

Service intervals

Manufacturer-recommended intervals for the Blue Star NG425-01 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter
Every 250 hours or 12 months
Coolant change
Every 4000 hours
Air filter
Every 1000 hours
Spark plugs
Every 1500 hours
Major overhaul
15,000 hours
Load bank test
Every 12 months

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.

ComponentSymptomTypical hoursSeverity
Turbocharger(s)Significant power loss, heavy exhaust smoke12,000+severe
Ignition system (multi-cylinder)Multiple misfires, output derating1,500+moderate
Charge air coolerReduced output, elevated intake temperatures10,000+moderate

Frequently Asked Questions

What is the standby rating of the NG425-01?
The Blue Star NG425-01 is rated 425 kWe standby on natural gas and 300 kWe standby on LP at 60 Hz / 1800 RPM. The LP-to-NG ratio at standby (71%) is typical for the PSI 21.9L V12 platform. Deration factors are standard: 1.5% per 10°F above 77°F inlet air temperature and 2.5% per 1,000 ft above 1,200 ft altitude.
What engine is in the NG425-01?
The PSI 21.9L — a 21.9-liter (1,338 cu in) V12 turbocharged-aftercooled spark-ignition engine producing 684 bHp (510 kWm) at 1800 RPM standby. The 21.9L V12 is the same platform used in the Blue Star NG400-01, NG425-01, and NG450-01 standby units, with electrical output tuned by the generator control system.
Is the NG425-01 available in single-phase?
No. The NG425-01 is three-phase only — 208V, 240V, 480V, and 600V configurations. Single-phase output is only available on Blue Star gaseous units up to 265 kW.
How does the NG425-01 compare to the NG400-01 and NG450-01?
All three use the PSI 21.9L V12 (684 bHp standby) and share the same 156×86×98 in footprint. The NG400-01 produces 400 kWe standby (300 kWe LP), the NG425-01 produces 425 kWe standby (300 kWe LP), and the NG450-01 produces 450 kWe standby (300 kWe LP). Selecting among them is primarily a matter of load margin — each shares identical alternator models at the 208V and 600V configurations.

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