Quieting Your Portable Generator for Home Use

hello many people use portable gasoline-powered generators to supply electrical power for their appliances or even their entire homes during power outages these portable generators are readily available and relatively inexpensive but their manufacturers did not intend them for extended use in residential neighborhoods the tiny mufflers on these generators is sufficient evidence of that while most neighborhoods are tolerant of generator noise during power outages many people wish for an easy and inexpensive way to cut down on the annoying racket coming from their generators this video shows my attempt to quiet my Briggs & Stratton model 0 3 0 4 6 9 which is a 6000 watt generator powered by a Briggs 342 cc or 20.8 5 cubic inch single cylinder gas engine with overhead valves capable producing starting 7500 watts this is a fairly large generator and it makes a lot of noise however my method should be useful for other similar generators of various sizes note that the method shown here does require a small amount of light and non-critical welding also I will use the term Jensen in the rest of this video to refer to the generator my approach is to add a small automotive muffler in addition to the gensets small built-in muffler a visit to the local auto parts store and a cost of about $65 provided me with all the necessary hardware the first step was to decide on the muffler and I chose a small one by thrush the store had the same muffler in two models that differed only in the diameter of the inlet and outlet fitting diameters and I chose the one with the two and a half inch fittings the choice of muffler fitting size determined the other parts needed these included two short flexible exhaust pipe sections to you bracket type exhaust clamps of two and a half inch size a two and a half inch outer diameter exhauster connector and an exhaust adapter which goes from two and 1/8 inch inner diameter to two and a half inch outer diameter now note that both of my flex pipes came with one u bracket clamp inside each of their boxes for a total of four such clamps this picture shows one flex pipe inside the box and another without a box as well as an extra solid pipe section that I ended up not using my genset had a decorative cover on its muffler which is not used in my scheme and it came off by removing four screws when the cover is removed the actual muffler is exposed most gensets in this category will have a spark arrestor mounted to the outlet of the muffler and it needs to be removed the spark arrestor comes off with four screws exposing the actual outlet hole of the genset muffler for some reason three of the four screws snapped off when I tried to remove them but since I was not going to use the spark arrestor anymore this did not present a problem next I used a wire brush to clean off the protective coating and some rust that was revealed when the spark arrestor was removed this is an important step in order to get a decent weld the small end of the adapter was sized to surround the genset muffler outlet hole while remaining small enough to not extend over the edge of the muffler or collide with the weldment next to the spark arrestor the large end of the adapter needed to match the Flex pipes which in turn needed to match the fitting on the car muffler all of which are two and a half inches note that the Flex pipes are two and a half inch inner diameter while the solid fittings are two and a half inch outer diameter next I held the small end of the adapter up against the genset muffler and centered it with the hole I used my welder to tack the adapter in place with three spot welds around the perimeter where the adapter met the muffler next I placed a weld bead in between the tacks pot welds sealing the adapter to the genset muffler I am NOT a skilled welder but I managed to get a reasonably uniform bead which I then spoiled cosmetically when I tried to place spots of weld to close the holes where the spark arrestor screws had been the next step was to attach one of the two flex pipes to the car muffler for some reason I found that even though the muffler inlet fitting was marked on the box as being two and a half inches it was actually a bit smaller and the Flex tubes two and a half inch inner diameter was too large to fit well I fixed this by using tin snips to cut a strip of scrap tin which I then wrapped twice around the car muffler Inlet fixture to increase its diameter slightly then I used one of the u bracket clamps to firmly attach the end of the Flex pipe to the car muffler inlet fitting next I joined the two flex pipes with the exhaust connector and to u bracket clamps this picture shows the car muffler and flex pipe assembly I used the two lengths of flex pipe to get it long enough to allow the car muffler to lay flat on the ground different arrangements here may be needed for other gen sets and different situations also I would have preferred to use a single length of flex pipe but none of the stores in my area carried anything longer than what I ended up buying finally I attached the Flex pipe to the adapter that I previously welded to the genset muffler this time I did not tighten the u bracket clamps so much since doing so would have crimped the Flex pipe making it more difficult to remove in order to facilitate storage of the genset or indeed using the genset in its original portable configuration now this video will show a series of tests that I did to determine the effectiveness of the new muffler I started out with the genset positioned in front of my open garage I decided to conduct all sound level tests from a distance of 20 feet away in reality no neighbor is even that close to the genset so they would hear even lower sound levels also note that my video levels are not calibrated on my end or on your computer so you can only rely on the apparent differences in sound level and on the kind of sound resulting from each change in testing my Radio Shack sound level meter was set to react to the full frequency range of human hearing or the a weighting in other words the meter is reacting to all all audible frequencies produced by the genset both the low frequencies of the exhaust itself and the higher frequencies of the non exhaust motor noise and also the sounds produced by the actual generator itself at 20 feet from the gen set I measured 82 decibels with the gen set running the way it came from the factory the next test was to connect the car muffler to the gen set the sound level meter gave a reading of 80 decibels with the car muffler added a reduction in two decibels which does not sound like a lot just looking at the numbers but you can hear that the low frequencies have been greatly reduced most of the racket you can hear and which the sound level meter was responding to a higher frequencies coming from the motor itself such as valve clatter and such as well as a word and wine from the actual generator the next test was to move the genset inside the garage and close the door as much as possible leaving the flex pipe passing underneath the sound level meter gave a reading of 71 decibels with the garage door mostly closed but quite a bit of higher frequency noise still escaped under the door the next test was to try and block most noise from sneaking under the door so I jammed some old tarps and plastic sheet and scrapped a bubble wrap under the door the sound level meter gave a reading of 69 decibels with the genset inside the closed and sealed garage and only the car muffler outside the gen set could run for days this way since the exhaust is going outside although it might be a good idea to direct a fan of the gen set for ventilation and cooling and leave enough leaks to allow at least some fresh oxygen bearing air into the garage finally this video includes a demonstration of how much the sound level changes when the garage door is opened up again I place the camera on a cinder block and this was not the best thing to do since the proximity effect amplifies the apparent sound level making everything seem a bit louder especially the low frequencies which are actually noticeably lower in reality I consider my method of modifying my genset for lower noise levels to be a success I hope that you're able to use this information to modify your own genset in a similar fashion

Channel: youtuuba

Views: 2,441,979

Keywords: generator, portable generator, muffler, briggs & stratton

Id: JjeJaqahP3E

Length: 10min 38sec (638 seconds)

Published: Sun Feb 17 2013