Muffler ideas to quiet generator?

[Egon]

Ive heard that some smaller generators may have a problem with a full out muffler, causes too much back pressure on the system. Not sure how true that is./QUOTE]

I'd assume a larger muffler would have less restriction just due to larger piping?

The frequencies of all the generator produced noise may make a difference on how it can be made less noisy.:thumbsup:

 

[SGBotsford]

Things to try:

1. Use a flex pipe and run the exhaust into a post hole.

2. Build a box out of strawbales. Bridge the top with a sheet of plywood or OSB. Paint the OSB really well -- it will turn to mush otherwise. Maybe some scrap roofing tin would help. Bales on top too. This is a real pain in the butt if you have a pull starter. You also want keep the gas tank outside the enclosure.

Of course you can make this big enough to go inside.

Duct the exhaust outside, using one of the other tricks.

3. An generator operates at 3600 rpm. But it sparks only every other revolution. So that's 30 explosions per second. Sound moves at roughly a thousand feet per second. So in 1/30 of a second it moves 30 feet. Try putting a 15 foot long side tube after the muffler with a closed end. Run an exhaust pipe for 15 feet also. This *may* create a tuned resonance that cancels most of the noise out.

Note that because the exhaust is hot, the speed of sound is higher. (Roughly linear with absolute temperature) So if the exhaust is 500 degrees F, you will need twice the pipe.

4. Exhaust into a barrel set in the ground. Exhaust at the the bottom of the barrel. Fill the barrel with grape fruit sized rocks.

5. Exhaust into a coil of weeping tile pipe, set just under water You don't want the holes too far under or it will create too much back pressure.

If you use a diesel genset, then having a VERY well insulated building with temperature controlled shutters can reduce the problems with the engine running cold. In essence you keep the room at close to the optimum temperature for the engine when it's idling, and bring in extra cooling air only when it is under load.