Acoustic enclosures are one of the most effective solutions for controlling noise from diesel-driven pump sets. A well-designed enclosure not only reduces noise but also ensures proper cooling, accessibility for maintenance, safety compliance, and long equipment life.
This section expands on the engineering considerations for designing and applying acoustic enclosures in pump installations.
Noise Control Objectives
Target Noise Levels
- Construction & mining sites: typically ≤85 dB(A) at 1 m
- Urban/residential projects: often 65–75 dB(A) at 7 m
- Critical environments (hospitals, data centres): <60 dB(A) at boundary
Frequency Spectrum
- Diesel noise is broadband, with dominant low-frequency components (engine block & exhaust at 63–250 Hz)
- Effective enclosures must block both low-frequency (hard to attenuate) and high-frequency noise
Construction Features
A. Walls & Panels
- Double-skin steel or aluminium panels with sound-absorbing insulation in between
- Typical thickness: 50–100 mm depending on target noise reduction
- Materials:
- Outer skin: galvanised steel (powder coated for corrosion resistance)
- Core: mineral wool, acoustic foam, or composite damping layers
- Panels must be non-combustible and vibration-damped
B. Doors & Access Panels
- Gasket-sealed, lockable access doors for maintenance access
- Hinged or removable panels allow servicing of filters, oil changes, and engine inspection
- Special hatch openings for radiator, exhaust, and control panel access
C. Acoustic Seals & Joints
- Every opening, seam, or joint is a potential noise leak
- Use neoprene or EPDM acoustic seals on doors, panels, and cable entries
- Bolt-on panels should overlap with labyrinth joints to reduce leakage
Ventilation & Cooling
Cooling is the biggest challenge in acoustic enclosure design. A diesel engine generates significant heat, and airflow must be managed without compromising noise attenuation.
Air Intake Louvres
- Lined with acoustic baffles to absorb noise while allowing airflow
- Designed with split-path or labyrinth silencers to prevent direct line-of-sight noise escape
Discharge Louvres
- Positioned to ensure hot air is expelled without recirculating into intake
- Often fitted with axial fans for forced ventilation
Airflow Rate
- Must match engine manufacturer cooling requirements
- Typically designed for air velocity ≤6–8 m/s to avoid fan/duct noise
Exhaust Silencing
Critical or residential-grade silencers are installed inside or adjacent to the enclosure.
Exhaust Pipes Must Be:
Flexible-coupled to prevent vibration transfer
Insulated to reduce radiant heat inside the enclosure
Routed through acoustically lined exhaust ducts to further reduce breakout noise
Vibration Isolation
The pump and engine skid must be mounted on anti-vibration mounts to prevent structure-borne noise
Enclosure baseframes should be designed to resist vibration amplification
Where enclosure is containerised (e.g., 20-ft ISO container), floors may require damping mats to reduce resonance
Safety & Maintenance
Fire Safety
- Materials should be fire-retardant
- Enclosures should include fire detection and suppression systems where required
Accessibility
- Doors and panels must allow safe servicing without dismantling the enclosure
- Internal lighting improves safety for maintenance tasks
Lifting & Transport
- Integrated lifting lugs or forklift pockets for moving containerised units
- Structural rigidity for road transport and site handling
Acoustic Performance
Unenclosed diesel pump
~95–100 dB(A)
at 1 m
Basic enclosure
~80–85 dB(A)
at 1 m
Full acoustic container
~65–75 dB(A)
at 7 m
Super-silenced
~55–60 dB(A)
at boundary
Case Study
Urban Flood Control Project
A diesel-driven dewatering pump (400 kW engine) was required to meet 70 dB(A) at 7 m.
Solution: 20-ft Acoustic Container
75 mm mineral wool insulation in double-skin walls
Split-path inlet and outlet air silencers
Critical-grade exhaust silencer with thermal insulation
Heavy-duty anti-vibration mounts
Result: Achieved 68 dB(A) at 7 m, well below compliance limit, while maintaining adequate engine cooling and full service access.
Summary
Diesel acoustic enclosures are highly engineered systems that balance noise reduction, airflow, durability, and serviceability. Effective designs rely on:
Double-skin insulated panels with acoustic seals
Labyrinth baffles for air intake/discharge
Integrated exhaust silencers
Anti-vibration isolation for structure-borne noise
Easy maintenance access without compromising acoustic integrity
For urban, regulated, or noise-sensitive projects, acoustic enclosures are no longer optional — they are essential.