Technical Guide: Choosing a Portable Diesel Compressor

2. Operating Pressure Range

• Standard site compressors run at 7–10 bar, but blasting and drilling may require up to 12–14 bar.

• Some models allow dual-pressure operation via electronic regulation.

• Always match compressor output pressure to the demand of your equipment to avoid over-fuelling or tool wear.

3. Fuel Efficiency & Engine Load

• Diesel engines (Kubota, Yanmar, Perkins, Deutz) dominate this sector.

• Look at specific fuel consumption (SFC), measured in L/hr at rated load.

• Stage V-compliant engines use DOC + DPF + SCR systems, which add complexity – factor in AdBlue consumption as well.

• A unit with higher efficiency at part-load can save thousands annually in fuel burn.

4. Noise Emissions

• Measured as sound pressure level LpA at 7m.

• EU Stage V units often fall in the 68–76 dB(A) range.

• For urban or night work, check whether the model has a “silenced canopy” option.

5. Cooling System & Duty Cycle

• Compressors running sandblasters or multiple pneumatic tools often operate at 100% duty cycle.

• Verify cooling capacity of both the engine radiator and aftercooler (if fitted).

• An undersized cooling system leads to derating (loss of airflow in hot ambient conditions).

6. Filtration & Aftercoolers

• Dry air is critical for blasting and precision tools.

• Options include:

  • Cyclone separators (removes bulk water)

  • Aftercoolers (reduces discharge temperature close to ambient)

  • Fine filtration (removes oil aerosols down to <0.01 mg/m³)

• Confirm the pressure drop across the filtration train, as this affects usable CFM.

7. Chassis & Tow Compliance

• Road tow models must comply with UK Construction & Use Regulations.

• Key checks:

  • Gross vehicle weight (under/over 750kg)

  • Braked vs unbraked chassis

  • Lighting, breakaway cable, and tow hitch type

• Site tow variants can save weight/cost but are restricted to internal movements.

8. Maintenance Intervals

• Compare engine and compressor service intervals (e.g. 500 hr vs 1000 hr).

• Check accessibility of filters, belts, and separators.

• Machines with modular service kits simplify logistics and reduce downtime.

9. Emissions Compliance

• Stage V engines are mandatory on most UK/EU sites.

• Verify the type of after-treatment system:

  • DOC (Diesel Oxidation Catalyst)

  • DPF (Diesel Particulate Filter – requires regeneration)

  • SCR (Selective Catalytic Reduction – requires AdBlue)

• Non-compliant imports may appear cheaper but can result in site bans.

10. Lifecycle Costing

When comparing units, calculate:

• Capex (initial purchase price)

• Opex (fuel, AdBlue, filters, oil, consumables)

• Residual value after 5–7 years

• Downtime risk (based on service network coverage)

A compressor with 5–10% higher efficiency often offsets a higher purchase price within 2 years of use.