In industrial screw terminology, low pressure is roughly ≤ 0.5 MPa (5 bar); medium pressure spans about 0.8–1.5 MPa (8–15 bar) for general plant air, while high/medium-pressure duty up to 40 bar serves PET blow molding and instrument/process air. CMN’s water-lubricated single-screw platform covers the full 2–40 bar band on one oil-free architecture.
Estimate required free air delivery (FAD) before selecting a model:
**FAD (Nm³/min) ≈ (bottle/part volume + dead space) × (absolute blow pressure ÷ atmospheric pressure) × cycles per minute**
For continuous plant air, size FAD from your tools’/process’s total consumption at the duty pressure, then add ~10–20 % margin for leaks and future growth.
A 1.5 L water bottle blown at 30 bar (≈ 4.0 bar gauge above 1 bar abs), 12,000 bottles/hour, ~5 s cycle, pre-blow 10 bar:
Per-bottle air ≈ (1.5 L + 0.3 L dead space) × (31/1) ÷ 3600 s ≈ ~0.0155 Nm³ per bottle
At 12,000 BPH → ≈ 14 Nm³/min ≈ 494 cfm at the blow pressure (pre-blow air is additional)
CMN’s 40 bar PET models (e.g. CM150GPV / CM242GPV class) are sized in this band; confirm exact FAD against the catalogue.
1. Required working pressure (bar) and pressure class (medium 8–15 / high 25–40).
2. Required FAD (cfm or Nm³/min) at that pressure, including margin.
3. Duty profile — steady or variable? → drives fixed-speed vs PMVSD.
4. Air-quality target — ISO 8573-1 Class 0 for food/pharma/PET.
5. Cooling — air-cooled or water-cooled site.
6. Certification evidence — request the model-specific TÜV Class 0 certificate.
Near-isothermal compression keeps discharge temperatures low even at 40 bar, avoiding the high thermal load that dry-type units face — a real advantage for continuous PET and process duty.
**Placeholder:** Replace model numbers and FAD figures with CMN’s verified catalogue values before publishing.
Request a sizing proposal with your pressure, FAD and duty cycle.
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