Reducing noise

[dpollo]

I will start here in the general section in the hopes it will  catch someome's attention.  I have a 2 cylinder  1800 rpm Lister15 HP belt-driving a 5 KW Kato alternator.  It is located in a bunker between two buildings and partially below ground. The top 2/3 of the structure and the door are all conventional frame.  I would like to reduce the mechanical noise from the Lister without making the enclosure  6'x4' by 7'high  too hot.  At present, a long run will raise inside temp to about 120 F.  I am thinking a double wall and ceiling with vents in the roof and at floor level.  Anybody else been there?    (The exhaust noise is acceptable as I presently have it with 2 mufflers in line and the outlet pointing up.)  dp

[rbodell]

I will start here in the general section in the hopes it will  catch someome's attention.  I have a 2 cylinder  1800 rpm Lister15 HP belt-driving a 5 KW Kato alternator.  It is located in a bunker between two buildings and partially below ground. The top 2/3 of the structure and the door are all conventional frame.  I would like to reduce the mechanical noise from the Lister without making the enclosure  6'x4' by 7'high  too hot.  At present, a long run will raise inside temp to about 120 F.  I am thinking a double wall and ceiling with vents in the roof and at floor level.  Anybody else been there?    (The exhaust noise is acceptable as I presently have it with 2 mufflers in line and the outlet pointing up.)  dp

http://www.youtube.com/rbodell#play/uploads/3/v1ZJ8e3ihZg
The stack has been removed and the exhaust is coming from the top of the drum. The stack is leaning against the building. The 55 gallon drum only holds dirt around the silencer which consists of a 30 gallon drum with no baffles. I used a drum with removable top so I could get bolts on the inside for one hole. the other is just threaded into the bung hole.

The noise you hear is the engine/valves from the engine, not the exhaust. The shed is not insulated.

I tried several mufflers and none worked very good. This silencer also cools the exhaust. I use a piece of PVC pipe for the exhaust from the drum.

[dpollo]

Thanks, rb.     dp

[Henry W]

Nice youtube post the silencer works very well.

Henry

[TimSR2]

Hi, I have a similar setup, an SR2 belt driven to a ST5 head.  If your set up is like mine most of your noise is actually air cleaner roar and cylinder 'whack'. Air cleaner roar is easily quietened by use of a Donaldson type filter chamber.

Fiberglass insulation and rough surfaced  panels in your shed walls will attenuate your high frequency diesel whack sound. You can use drywall or plywood, but a finished surface of ceiling tiles or Donnaconna board  will suck up the diesel knocks better than a hard surface will. For the air flow concerns a baffled and screened inlet and outlet at the bottom and top of the enclosure will do the trick. It can be built  as simply as a 2x12 divided  box section  stood off the siding of the building with a screen at the top and bottom, and hole saw holes  drilled through the wall into it.

Sound likes to travel in straight lines, but air flow can easily bend. That's why the best mufflers have 3 or more passes in them. You want to design cooling vents that will easily flow air but will force the sound to change direction, preferably a couple of times.

Tim

[Henry W]

What also helps is to use an automotive muffler on the intake.

Henry

[dpollo]

Thanks Tim, Henry and rb.    I am glad to learn I am on the right track here.  I have a Donaldson air filter now and the difference is noticeable. Two mufflers in line, one specifically designed for a Diesel of this size and the second, an automotive unit. Each is far more effective than the spark arrester that came with the engine, which is an ST2 originally employed as standby on a lighthouse.  I don't think it has more than a few hours use. Unfortunately, I did not get the direct connected alternator (1800rpm) but I already had the 5KW Kato (1200rpm) which I  had purchased two of from Crown assets for $76 each back in 1978.  Zero hour machines and nice units. My setup is functional and in the last year has run about 20 hours of serious line time and about the same again in test runs. Trigzy, (Stephen Todd) from the old site sold me an AVR which works perfectly. ($148 in Canada) .
I have two boxes of 12x24 ceiling tile and will support that on isolated studding and I can easily contrive the baffled vents.  It will take me a while, but I will let you know how it works..... Incidentally, I discovered the old site while trying to find out how to adjust the governor on the Lister. Once set, it maintains the speed perfectly through the entire load range.        Dave.

[TimSR2]

Hi Dave,

The ST2 has enough power to run that head at 1200 direct drive. I run 1400 rpm on  a SR2, with  belt drive and have no problem with  5kw full rated output. ST2 has more power; direct drive should be no problem. Chuff, chuff, chuff...... Less RPM equals less noise.

Tim

[dpollo]

Thanks, Tim , I agree, it should easily handle the loads at 1200.  Jens, as soon as the farm wraps up for the year, I will be in touch.  You have not yet seen the Hydro plant so we must get together.   dp