After determining your factory’s true air demand, the next critical step is selecting the right compressor—one that delivers the required performance at the lowest possible energy cost. This is where understanding energy efficiency standards, key metrics, and common procurement pitfalls becomes essential.
Dream compressors, as a Chinese industrial screw air compressor manufacturer exporting to over 50 countries, has deep expertise in helping international buyers navigate these complexities. This guide walks you through the selection process.
The single most important indicator of compressor efficiency is specific power, expressed as kW/(m³/min) or kW/100 cfm.
Definition: Specific power measures how much electrical energy is required to produce one unit of compressed air. The lower the specific power, the higher the efficiency.
Why specific power matters:
It accounts for total input power—including the main motor, cooling fan, and all electrical components—not just the motor nameplate rating.
It allows direct comparison between different compressor brands and models, regardless of claimed “motor efficiency.”
Example:
Compressor A: 6.5 kW/(m³/min)
Compressor B: 7.0 kW/(m³/min)
For a 10 m³/min system running 6,000 hours/year, Compressor A saves 30,000 kWh annually—a substantial cost reduction.
When sourcing compressors internationally, familiarity with key standards helps ensure you’re comparing apples to apples.
| Standard | Region | Key Feature |
| GB19153-2019 | China | Three-tier system (Grade 1 is most efficient). Uses total unit input power. Includes exergy efficiency for cross-pressure comparison. |
| EU Lot31 | European Union | Sets Minimum Energy Performance Standards (MEPS). Requires testing per ISO1217 with consideration of partial load. |
| US DOE 10 CFR Part 431 | United States | Mandates specific power testing for rotary screw compressors. Results are publicly available. |
Pro Tip: When comparing compressors from different regions, always request third-party test reports (ISO1217 or CAGI) and compare specific power at the same rated pressure.
| Operating Profile | Recommended Technology | Energy Saving Potential |
| Stable base load (minimal variation) | Fixed-speed rotary screw | Baseline efficiency; lowest initial cost |
| Fluctuating demand (common in most factories) | Variable Speed Drive (VSD) | 30–50% reduction compared to fixed-speed |
| Mixed profile with high base load + peak spikes | VSD + fixed-speed master/slave | 25–35% with optimized staging |
Important: VSD compressors are not always the answer. If demand is extremely stable, a well-selected fixed-speed compressor operating at full load can be equally efficient. However, most factories experience demand fluctuations, making VSD a strong candidate.
This is one of the most misunderstood areas in compressor procurement.
What is service factor (SF)?
Service factor allows a motor to operate above its rated power for short periods. Common SF values: 1.15, 1.20, 1.25, 1.35.
The trap:
A motor with a 75 kW nameplate rating and SF=1.25 can actually operate at 93.75 kW. Some manufacturers use this to:
The solution:
Always request the total unit input power (measured at full load), not the motor nameplate rating. Under GB19153-2019, this is the required basis for efficiency rating.
Dream compressors’ approach: We provide clear documentation of total unit input power for all models, ensuring transparent comparison.
When evaluating compressor bids, use this checklist:
FAQ
Q: Is a Grade 1 (GB19153) compressor always worth the higher initial cost?
A: In most cases, yes. The payback period for upgrading from Grade 3 to Grade 1 is typically 12–24 months based on energy savings. For systems running 24/7, the payback is often faster.
Q: How do I verify a supplier’s efficiency claims?
A: Request the original test report from a recognized laboratory (e.g., CAGI, TÜV, or China National Compressor Testing Center). Reputable manufacturers like Dream compressors can provide these upon request.
Q: What is the difference between specific power and exergy efficiency?
A: Specific power is a practical metric for comparing compressors at the same pressure. Exergy efficiency accounts for the thermodynamic quality of compressed air, allowing comparison across different pressure levels—a concept introduced in GB19153-2019.
Ready to select the most efficient compressor for your application?
Our engineering team can help you compare specific power values and select the optimal configuration.
WhatsApp: +86 136-7155-1445
Email: [email protected]
Dream compressors: Your reliable Chinese industrial screw air compressor manufacturer.
