How to quiet a portable generator

Written by pauline gill
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How to quiet a portable generator
Stacked sandbags can muffle sound. (sacs de sable image by Jerome Dancette from

Sound is an expression of inefficiency in processes that convert one form of energy to another. While pleasing sound is the desired result of energy conversion in musical instruments and vocalists, unwanted sound, or noise, continually challenges the designers of jet engines, jack hammers, and portable generators alike. Noise abatement science concentrates in two major areas; preventing the emission of unwanted noise in the first place; and then effectively blocking any remaining noise from the surroundings. Successfully quieting a portable generator involves both crafts.

Skill level:

Things you need

  • Damp washed sand
  • Sand bags
  • Two sections of 6-foot-by-6-foot fibreglass screening.
  • Ultra-soft urethane sheeting, 1/8 inch thick
  • Construction adhesive
  • Fuel hose and clamps
  • Workshop tools

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    Reduce Emitted Sound From the Generator

  1. 1

    Eliminate emitted sound from the generator itself by isolating its major sources -- the fuel tank, and exhaust outlet from any rigid enclosure.

    How to quiet a portable generator
    Flexible tubing can route exhaust away from an engine (engine detail image by Dumitrescu Ciprian from
  2. 2

    Select an outside location for the generator. The most significant single step is locating the generator outside any kind of building structure including houses, garages, and sheds. These only serve as highly efficient acoustic propagators.

  3. 3

    Remove the fuel tank from the top of the unit and mount it remotely in an enclosure in a shady place with good ventilation. Mount the tank higher than the engine as before and reconnect it and its shut off-valve with a length of fuel hose. You can run the fuel line through a plastic conduit underground as long as the hose is one continuous piece. Metal and plastic fuel tanks are efficient acoustic amplifiers, and isolating them from the generator is a huge contributor to quiet.

  4. 4

    Direct the engine's exhaust towards an effective acoustic absorber baffle. Fabricate a 3-foot-by-3-foot inert acoustic pillow by folding a 6-foot-by-3-foot piece of fibreglass screening in half and bonding three sides of it with hot melt glue. After the three sides are securely set, use the hot glue gun to create 4-inch open sections at the top. Fill each tube with sand until it will not hold any more. Seal the top of each 4-inch-by-36-inch section with hot melt glue and put aside until later.

  5. 5

    Negate the sound amplification effects of flat metal or plastic surfaces. Portable generators are loaded with flat surfaces. Clean them with a quick-solvent, and then cement 1/8-inch ultra-soft polyurethane damping material to them with a very thin layer of contact cement.

  6. 6

    Use sand bags to form an acoustic isolation ring around the generator for long-term use. Space the sand bags at least one foot away from the generator and stack them up on top of each other until the generator is no longer visible from 4-feet away.

  7. 7

    Cover the sandbags with limp vinyl sheet shower pan backing to keep them dry from precipitation. This will also help the soundproofing effort.

  8. 8

    Place the sand filled screening baffle against the sandbag wall about one foot in front of the muffler outlet. Alternatively pipe the exhaust to an automotive muffler inside the sandbag enclosure.

Tips and warnings

  • Avoid putting generators into rigid enclosures such as sheds, or garages.
  • Avoid electrical shock when working with a generator.
  • Never discharge engine exhaust inside a building or shed.

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