Author Topic: Trying to Quieten the 110KVA Generator  (Read 4806 times)

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #100 on: October 21, 2020, 03:26:44 PM »
Well throwing caution to the wind I did fire it up with a full compliment of Ďinmatesí ensconced in their cottages. With the incomplete ceiling I am measuring 60 dBa at the gate to their courtyard occasionally dropping to 59 dBa.

There is a noticeable decrease in the noise which presumably will continue to improve as I finish the ceiling. Iím expecting the exhaust radiator air tunnel to improve things as well.

However Iím conscience not to run the generator too long at the moment as there is masses of Rockwool bits around to clog air filters.
Andrew Mawson
East Sussex

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #101 on: October 22, 2020, 03:28:35 PM »
Today I got the last of the Rockwool sound insulation installed. The last panel was a bit of a pain as it needed a 50 mm 'extra' bit fitting that for the life of me I couldn't get to stay put as I fixed the mesh. Cosmetically not ideal but probably has zero effect on the sound deadening!

So what's the results?

Well when I began I was measuring 107 dBa adjacent to the generator, and 71 dBa by the cottages courtyard (this last figure seems to have been recorded optimistically low by me on earlier posts)

Now I am measuring on brief tests today 95 dBa inside the generator room, and 59/60 dBa by the cottages courtyard.

The 12 dBa reduction in the generator room is obviously very significant but I'm surprised the the remote reading isn't less, though it IS the same 11/12 dBa reduction.

. . . still got the canvas 'radiator exhaust tunnel' to go !

Apart from the canvas, re-installing a spot light fitting, and a major hoovering up that's about it for the generator room.
Andrew Mawson
East Sussex

Offline russ57

  • Full Member
  • ***
  • Posts: 235
Re: Trying to Quieten the 110KVA Generator
« Reply #102 on: October 22, 2020, 05:35:36 PM »
12db is pretty good - a subjective reduction to 1/4 if I recall my acoustics.

Are you planning to seal the rockwool in any way? Even a light spray paint would help I would think, without affecting the performance.


A walk around the enclosure with the meter may pinpoint any significant 'spot' leaks. Covering those with lead sheet ought to help.

Last question - does the generator noise vary with load?



-russ


Offline AdeV

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2380
  • Country: gb
Re: Trying to Quieten the 110KVA Generator
« Reply #103 on: October 23, 2020, 02:52:19 AM »
Apparently, 60dbA is about the equivalent noise level to a conversation in a restaurant.... so not bad, considering the size of the engine. If you've got a few quid left over, you could always add a layer of AcoustiBlok (tm) sheet - this is (apparently) seriously sound-deadening stuff - their 6mm sheet is claimed to reduce sound levels by 32dbA, which would get you nicely below "Library" sound levels (40dbA). Since their website doesn't quote prices, you know it's going to be dear...

I was planning to use this to keep a generator quiet on my transporter; but after I stopped racing some mumbleteen years ago, the project lost any sense of urgency it might have had in the first place...
Cheers!
Ade.
--
Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #104 on: October 23, 2020, 02:56:09 AM »
Russ Iíve been considering some sort of spray to make it less friable but paint would be inflammable so my thought at the moment are along the lines of a solution of sodium silicate.

Iím sure that the generator note will change with load, in fact I know it does, but the actual noise level subjectivity seems the same.

To biggest escape point is probably the door where I have those pvc strips, but I canít block it as loads of air is needed for cooling and combustion.
Andrew Mawson
East Sussex

Offline RussellT

  • Sr. Member
  • ****
  • Posts: 491
  • Country: gb
Re: Trying to Quieten the 110KVA Generator
« Reply #105 on: October 23, 2020, 04:53:00 AM »
That sounds like a good result to me.

Can you do anything to the floor?

Russell
Common sense is unfortunately not as common as its name suggests.

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #106 on: October 23, 2020, 05:03:25 AM »
Probably not Russell, itís very uneven concrete, about all I could possibly do is lay some cork tiles, but theyíd not lay flat and be a trip hazard
Andrew Mawson
East Sussex

Offline russ57

  • Full Member
  • ***
  • Posts: 235
Re: Trying to Quieten the 110KVA Generator
« Reply #107 on: October 23, 2020, 05:27:22 AM »
You need some sort of 'labyrinth' or baffle so the noise has to bounce around to escape.

Like this
 - - - -   - - - -
     -  - - - -
------       - - - - - -

This technique is used eg to reduce sound from a dust extraction enclosure.

Would paint really be flammable once it dries? I thought after the solvent is gone, it's mainly pigment and binder especially water based.

For the floor, what about that soft-fall used in playgrounds? Some sort of crumb rubber.

Or carpet / outdoor carpet / artificial grass..

Really make the cell comfy...



-russ


Offline Muzzerboy

  • Jr. Member
  • **
  • Posts: 69
  • Country: gb
    • The Mighty Shiz
Re: Trying to Quieten the 110KVA Generator
« Reply #108 on: October 23, 2020, 08:15:46 AM »
Seems the new thing in sound engineering is "psychoacoustics". Fancy sounding stuff but it refers to the nature of the noise as much as the absolute noise level itself. For example, a leaf blower may not be massively noisy but could get you killed, whereas a serene throbbing noise at the same level might make you friends. I suspect I have a fairly good idea what a loaded diesel generator sounds like ie not too unpleasant.

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #109 on: October 23, 2020, 08:48:55 AM »
Well a friend popped round yesterday and I demonstrated the generator and itís noise and he, being an ex HGV driver was  ecstatic about the sound. Thought it sounded great!

But I can imagine that if you are on a long awaited paid for holiday itís perhaps not what you want while dining al fresco in the courtyard  :clap:
Andrew Mawson
East Sussex

Offline russ57

  • Full Member
  • ***
  • Posts: 235
Re: Trying to Quieten the 110KVA Generator
« Reply #110 on: October 23, 2020, 09:06:34 AM »
Offer the guests a custom cast souvenir...
Maybe cast iron earmuffs...

-russ


Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #111 on: October 24, 2020, 11:26:18 AM »
Today I extended the radiator surround forwards towards the west wall by about eight inches.

This will allow me to use a single width of the canvas as a wrap and give sufficient overlap for fixing, otherwise I'd have had to join two strips of canvas which would have been a bind.

Need to make and fix a grill to keep insects out, then the canvas can go on.
Andrew Mawson
East Sussex

Offline hermetic

  • Hero Member
  • *****
  • Posts: 544
  • Country: england
Re: Trying to Quieten the 110KVA Generator
« Reply #112 on: October 24, 2020, 11:45:02 AM »
Neat work on the radiator extension Andrew, but we wouldn't expect anything less from you! How about some industrial rubber conveyor belt between the woods that the genny is standing on and the floor, might stop the floor becoming so much of a transfer medium for the sound.
Man who says it cannot be done should not disturb man doing it! https://www.youtube.com/user/philhermetic/videos?

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #113 on: October 25, 2020, 10:09:16 AM »
With the help of  a friend I managed to get the canvas wrapped round the wall flange and  radiator extension, and fixed with 25 mm strips of Zintec pop riveted through the canvas. Prior to wrapping I put gaffer tape over the raw edges of the wall cowl and radiator extension to hopefully prevent the canvas chaffing.

Needless to say it was not ever so easy, but rare earth magnets came to the rescue holding the canvas while I fixed the strips on. I'd intended to use double sided carpet tape to hold  it temporarily in place, but as the canvas is waxed it didn't stick!

Once it was in place and the seam crimped together with clothes pegs I was able to tack stitch the seam with rather crude tacks and the pegs could be removed.

Starting the generator it was immediately apparent that the airflow was now completely different. Before the radiator air was re-circulating but now the hot air is expelled and fresh drawn in through the PVC door strips, which now billow inwards. I feared that the door being partly open would increase the external noise but I'm still measuring 60 dBa at the cottage courtyard.

It's amusing to see how the 'tunnel' inflates as the generator is running.

. . . just the outer grill to make and fit, but it's pouring down so it will have to wait.
Andrew Mawson
East Sussex

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #114 on: October 25, 2020, 12:42:40 PM »
Rain barely stopped all afternoon, but as I have the original cowl, where I cocked up the flange, I was able to use it to model the vermin mesh.

Mesh cut and bent and ready to fit when weather permits!

It is slightly finer than I would have chosen as no doubt it will give a bit of air resistance, but I had it in stock so have used it. Can always re-make it  later in a coarser mesh if it gives problems, but I think that the engine is adequately cooled and anyway will only be used for short(ish) runs.

Andrew Mawson
East Sussex

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8019
  • Country: gb
  • East Sussex, UK
Re: Trying to Quieten the 110KVA Generator
« Reply #115 on: October 26, 2020, 06:40:38 AM »
A slight respite from the rain this morning, I even spotted the sun at one time - so I sprang into action and fitted the 'rodent mesh' into the radiator exhaust flange. Just a drilling and bolting affair - nothing too complicated.

Air flow doesn't seem to be unduly affected - no doubt the over pressure in the canvas tunnel will be greater, however having a 45 degree cut off on the cowl has increased the discharge area by about 40% so the impedance of the mesh perhaps isn't anything to worry about!
« Last Edit: October 27, 2020, 06:22:37 AM by awemawson »
Andrew Mawson
East Sussex