Silent Diesel Generators Explained
Every Greaves diesel generator we sell today is a "silent" DG set — but the word means something specific. Here's what "silent" actually delivers and where it matters.
The Indian sound norm: 75 dB at 1 metre
The Central Pollution Control Board (CPCB) caps diesel generator noise at 75 dB(A) measured 1 metre from the acoustic canopy, in a free field. For context:
- Normal conversation: 60 dB
- Vacuum cleaner: 70 dB
- Silent DG at 1 m: 75 dB
- Open DG (no canopy) at 1 m: 95–105 dB
Every 10 dB drop halves perceived loudness — a canopy makes a huge practical difference.
How an acoustic canopy works
A silent canopy is more than a metal box. It's engineered to absorb and redirect sound while still allowing airflow for cooling and combustion. Key elements:
- Multi-layer acoustic foam lining the interior walls
- Baffled inlet and outlet vents that let air in but block direct sound paths
- Residential-grade exhaust silencer reducing engine exhaust noise by 30–35 dB
- Anti-vibration mounts isolating the engine from the canopy skin
- Sealed service doors with acoustic gaskets
CPCB IV+ compliance
From July 2023, every new diesel generator sold in India must meet CPCB IV+ emission norms — significantly lower NOx and particulate matter than the earlier CPCB II. Every Greaves DG set Mecwel Engineers supplies is CPCB IV+ certified, with the certificate included at handover.
Where silent DGs are mandatory
- Residential and mixed-use zones under pollution board rules
- Hospitals, schools, courts and government buildings
- Hotels and hospitality
- Any DG installed within 15 metres of a habitable building
Non-silent open DG sets are effectively no longer sold for these applications in Guwahati or across Assam.
Silent DG vs "super silent"
Some vendors market "super silent" units at 65–70 dB. These use thicker foam and larger canopies and cost 15–25% more. For hospitals near patient wards, boutique hotels, luxury residences or premium office atriums, the extra spend is worth it. For most industrial and commercial sites, standard silent (75 dB) is sufficient.
Installation matters as much as the canopy
A 75 dB silent DG placed against a reflective concrete wall can measure 85 dB in practice because sound bounces. Proper installation includes:
- Minimum 1.5 m clearance around the canopy
- Exhaust routed clear of neighbouring windows
- Anti-vibration pads under the DG base frame
- Fuel tank vent piped to safe location
- Earthing to code
Mecwel Engineers handles all of this as part of standard commissioning across Guwahati and Assam.
Ready to power your business? Get a free quote from Mecwel Engineers — Guwahati's authorized Greaves Cotton dealer since 1991. Call +91 97060-11988 for on-site load survey and pricing across Assam.