Industrial Overview
Continuous blasting requires a massive, stable volume of compressed air (CFM). The choice between a **Rotary Screw** and a **Reciprocating (Piston)** compressor is the difference between industrial scale productivity and intermittent utility work. For sandblasting, where nozzle pressure must remain constant, the compressor's duty cycle is the primary technical constraint.
Rotary Screw
Engineered for 100% duty cycles. Uses two interlocking helical screws to provide constant, pulse-free airflow for continuous heavy-duty blasting.
Reciprocating
Engineered for intermittent use. Uses pistons to compress air into a receiver. Ideally suited for small workshops or spot-blasting tasks.
Blasting Performance Table
| Metric | Reciprocating (Piston) | Rotary Screw (APEX) |
|---|---|---|
| Duty Cycle | 60% - 70% (Needs Cool Down) | 100% (Continuous) |
| CFM Stability | Pulsating / Fluctuating | Constant / Flat-Line |
| Oil Carryover | High (Needs Heavy Filtration) | Minimal (Integrated Separators) |
| Noise Level | 85+ dB (Very Loud) | 65 - 75 dB (Enclosed) |
| Energy Efficiency | Lower at high load | High (VFD Compatible) |
| Blasting Nozzles | Small (1/4" and below) | Large (Up to 1/2" Venturi) |
Reciprocating Choice
- Low initial capital expenditure.
- Simple mechanical repairs in the field.
- Suitable for spot-repairs and touch-ups.
Rotary Screw Choice
- 24/7 continuous blasting capability.
- Low maintenance frequency (8000hr service).
- Critical for maintaining Sa 2.5 production.
Frequently Asked Questions
Is a rotary screw compressor better for sandblasting than a piston compressor?
Yes — for continuous blasting. Rotary screw compressors: continuous 100% duty cycle, oil-free air (with separator), stable CFM output, 68-72 dB(A) noise. Piston compressors: intermittent duty (50-70% max), oil carryover risk, CFM fluctuates, 85-95 dB(A) noise. For professional blasting with 4+ hours/day operation, rotary screw is the industry standard.
What is the minimum CFM for reliable sandblasting?
Minimum reliable: 100 CFM at 7 bar for a single #4 nozzle (6.4mm). This requires a 30 kW rotary screw or 7.5 kW piston compressor. Rule of thumb: each nozzle consumes approximately 30-35 CFM per 1mm of bore. #6 (9.5mm): 180-210 CFM. #8 (12.7mm): 350-400 CFM. Undersizing the compressor causes pressure drop below 4 bar.
What maintenance does a rotary screw compressor need?
Daily: check oil level, drain condensate from receiver tank. Weekly: inspect air filter (blow out or replace if gray), check belt tension. Monthly: change air filter element, verify pressure settings. Every 2,000 hours: change oil, replace separator element, inspect intake valve. Every 10,000 hours: full air-end inspection. Keep service records for warranty claims.