Brake horsepower (BHP) vs nameplate HP

Brake horsepower (BHP) and nameplate HP are not the same number. BHP is the shaft power actually consumed by the compressor air end at its rated operating point. Nameplate HP is the motor rating, and must equal or exceed BHP plus drive losses and any margin for service factor.

What it is

If a rotary screw air end needs 92 BHP to deliver 500 SCFM at 100 psig, a 100 HP motor with 1.15 service factor easily covers it (covering belt or coupling losses). The package’s CAGI data sheet reports package input power in kilowatts, which is the wall-plug number that converts back to brake horsepower at the air end via motor and drive efficiencies. CAGI specific power (kW/100 SCFM) is the apples-to-apples efficiency metric.

Why it matters

Marketing literature occasionally headlines “100 HP” without specifying brake or nameplate. The right number to compare across machines is CAGI package input kilowatts at full load, because that is what the utility bill is based on. Nameplate HP alone tells you nothing about efficiency.

How it is used in our catalog

Every compressor entry surfaces both nameplate HP (motor rating) and CAGI package input kW where the manufacturer publishes a sheet. Compare across rotary screw compressors on specific power, not nameplate.

Common questions

Why is BHP usually lower than nameplate HP?

Motors are sized to handle peak load with service factor margin. The air end typically operates at 85-95 percent of nameplate at design conditions.

What number should appear in my electrical load schedule?

Package full-load kW from the CAGI data sheet, divided by power factor (typically 0.92-0.95), is the kVA load. Not nameplate HP.